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<div class="section" id="module-cqlengine.queryset">
<span id="making-queries"></span><h1>Making Queries<a class="headerlink" href="#module-cqlengine.queryset" title="Permalink to this headline">¶</a></h1>
<div class="section" id="retrieving-objects">
<h2>Retrieving objects<a class="headerlink" href="#retrieving-objects" title="Permalink to this headline">¶</a></h2>
<blockquote>
<div>Once you’ve populated Cassandra with data, you’ll probably want to retrieve some of it. This is accomplished with QuerySet objects. This section will describe how to use QuerySet objects to retrieve the data you’re looking for.</div></blockquote>
<div class="section" id="retrieving-all-objects">
<h3>Retrieving all objects<a class="headerlink" href="#retrieving-all-objects" title="Permalink to this headline">¶</a></h3>
<blockquote>
<div><p>The simplest query you can make is to return all objects from a table.</p>
<p>This is accomplished with the <code class="docutils literal"><span class="pre">.all()</span></code> method, which returns a QuerySet of all objects in a table</p>
<p>Using the Person example model, we would get all Person objects like this:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">all_objects</span> <span class="o">=</span> <span class="n">Person</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
</pre></div>
</div>
</div></blockquote>
</div>
<div class="section" id="retrieving-objects-with-filters">
<span id="id1"></span><h3>Retrieving objects with filters<a class="headerlink" href="#retrieving-objects-with-filters" title="Permalink to this headline">¶</a></h3>
<blockquote>
<div><p>Typically, you’ll want to query only a subset of the records in your database.</p>
<p>That can be accomplished with the QuerySet’s <code class="docutils literal"><span class="pre">.filter(\*\*)</span></code> method.</p>
<p>For example, given the model definition:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Automobile</span><span class="p">(</span><span class="n">Model</span><span class="p">):</span>
<span class="n">manufacturer</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">Text</span><span class="p">(</span><span class="n">primary_key</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
<span class="n">year</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">Integer</span><span class="p">(</span><span class="n">primary_key</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
<span class="n">model</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">Text</span><span class="p">()</span>
<span class="n">price</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">Decimal</span><span class="p">()</span>
<span class="n">options</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">Set</span><span class="p">(</span><span class="n">columns</span><span class="o">.</span><span class="n">Text</span><span class="p">)</span>
</pre></div>
</div>
<p>…and assuming the Automobile table contains a record of every car model manufactured in the last 20 years or so, we can retrieve only the cars made by a single manufacturer like this:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Tesla'</span><span class="p">)</span>
</pre></div>
</div>
<p>You can also use the more convenient syntax:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="p">(</span><span class="n">Automobile</span><span class="o">.</span><span class="n">manufacturer</span> <span class="o">==</span> <span class="s1">'Tesla'</span><span class="p">)</span>
</pre></div>
</div>
<p>We can then further filter our query with another call to <strong>.filter</strong></p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">year</span><span class="o">=</span><span class="mi">2012</span><span class="p">)</span>
</pre></div>
</div>
<p><em>Note: all queries involving any filtering MUST define either an ‘=’ or an ‘in’ relation to either a primary key column, or an indexed column.</em></p>
</div></blockquote>
</div>
</div>
<div class="section" id="accessing-objects-in-a-queryset">
<h2>Accessing objects in a QuerySet<a class="headerlink" href="#accessing-objects-in-a-queryset" title="Permalink to this headline">¶</a></h2>
<blockquote>
<div><p>There are several methods for getting objects out of a queryset</p>
<ul>
<li><dl class="first docutils">
<dt>iterating over the queryset</dt>
<dd><div class="first last highlight-python"><div class="highlight"><pre><span></span><span class="k">for</span> <span class="n">car</span> <span class="ow">in</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">all</span><span class="p">():</span>
<span class="c1">#...do something to the car instance</span>
<span class="k">pass</span>
</pre></div>
</div>
</dd>
</dl>
</li>
<li><dl class="first docutils">
<dt>list index</dt>
<dd><div class="first highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
<span class="n">q</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="c1">#returns the first result</span>
<span class="n">q</span><span class="p">[</span><span class="mi">1</span><span class="p">]</span> <span class="c1">#returns the second result</span>
</pre></div>
</div>
<div class="last admonition note">
<p class="first admonition-title">Note</p>
<ul class="last simple">
<li>CQL does not support specifying a start position in it’s queries. Therefore, accessing elements using array indexing will load every result up to the index value requested</li>
<li>Using negative indices requires a “SELECT COUNT()” to be executed. This has a performance cost on large datasets.</li>
</ul>
</div>
</dd>
</dl>
</li>
<li><dl class="first docutils">
<dt>list slicing</dt>
<dd><div class="first highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
<span class="n">q</span><span class="p">[</span><span class="mi">1</span><span class="p">:]</span> <span class="c1">#returns all results except the first</span>
<span class="n">q</span><span class="p">[</span><span class="mi">1</span><span class="p">:</span><span class="mi">9</span><span class="p">]</span> <span class="c1">#returns a slice of the results</span>
</pre></div>
</div>
<div class="last admonition note">
<p class="first admonition-title">Note</p>
<ul class="last simple">
<li>CQL does not support specifying a start position in it’s queries. Therefore, accessing elements using array slicing will load every result up to the index value requested</li>
<li>Using negative indices requires a “SELECT COUNT()” to be executed. This has a performance cost on large datasets.</li>
</ul>
</div>
</dd>
</dl>
</li>
<li><dl class="first docutils">
<dt>calling <code class="xref py py-attr docutils literal"><span class="pre">get()</span></code> on the queryset</dt>
<dd><div class="first highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Tesla'</span><span class="p">)</span>
<span class="n">q</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">year</span><span class="o">=</span><span class="mi">2012</span><span class="p">)</span>
<span class="n">car</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">get</span><span class="p">()</span>
</pre></div>
</div>
<p class="last">this returns the object matching the queryset</p>
</dd>
</dl>
</li>
<li><dl class="first docutils">
<dt>calling <code class="xref py py-attr docutils literal"><span class="pre">first()</span></code> on the queryset</dt>
<dd><div class="first highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Tesla'</span><span class="p">)</span>
<span class="n">q</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">year</span><span class="o">=</span><span class="mi">2012</span><span class="p">)</span>
<span class="n">car</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">first</span><span class="p">()</span>
</pre></div>
</div>
<p class="last">this returns the first value in the queryset</p>
</dd>
</dl>
</li>
</ul>
</div></blockquote>
</div>
<div class="section" id="filtering-operators">
<span id="query-filtering-operators"></span><h2>Filtering Operators<a class="headerlink" href="#filtering-operators" title="Permalink to this headline">¶</a></h2>
<blockquote>
<div><p><code class="xref py py-attr docutils literal"><span class="pre">Equal</span> <span class="pre">To</span></code></p>
<blockquote>
<div><p>The default filtering operator.</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Tesla'</span><span class="p">)</span>
<span class="n">q</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">year</span><span class="o">=</span><span class="mi">2012</span><span class="p">)</span> <span class="c1">#year == 2012</span>
</pre></div>
</div>
</div></blockquote>
<p>In addition to simple equal to queries, cqlengine also supports querying with other operators by appending a <code class="docutils literal"><span class="pre">__<op></span></code> to the field name on the filtering call</p>
<p><code class="xref py py-attr docutils literal"><span class="pre">in</span> <span class="pre">(__in)</span></code></p>
<blockquote>
<div><div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Tesla'</span><span class="p">)</span>
<span class="n">q</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">year__in</span><span class="o">=</span><span class="p">[</span><span class="mi">2011</span><span class="p">,</span> <span class="mi">2012</span><span class="p">])</span>
</pre></div>
</div>
</div></blockquote>
<p><code class="xref py py-attr docutils literal"><span class="pre">></span> <span class="pre">(__gt)</span></code></p>
<blockquote>
<div><div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Tesla'</span><span class="p">)</span>
<span class="n">q</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">year__gt</span><span class="o">=</span><span class="mi">2010</span><span class="p">)</span> <span class="c1"># year > 2010</span>
<span class="c1"># or the nicer syntax</span>
<span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">Automobile</span><span class="o">.</span><span class="n">year</span> <span class="o">></span> <span class="mi">2010</span><span class="p">)</span>
</pre></div>
</div>
</div></blockquote>
<p><code class="xref py py-attr docutils literal"><span class="pre">>=</span> <span class="pre">(__gte)</span></code></p>
<blockquote>
<div><div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Tesla'</span><span class="p">)</span>
<span class="n">q</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">year__gte</span><span class="o">=</span><span class="mi">2010</span><span class="p">)</span> <span class="c1"># year >= 2010</span>
<span class="c1"># or the nicer syntax</span>
<span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">Automobile</span><span class="o">.</span><span class="n">year</span> <span class="o">>=</span> <span class="mi">2010</span><span class="p">)</span>
</pre></div>
</div>
</div></blockquote>
<p><code class="xref py py-attr docutils literal"><span class="pre"><</span> <span class="pre">(__lt)</span></code></p>
<blockquote>
<div><div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Tesla'</span><span class="p">)</span>
<span class="n">q</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">year__lt</span><span class="o">=</span><span class="mi">2012</span><span class="p">)</span> <span class="c1"># year < 2012</span>
<span class="c1"># or...</span>
<span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">Automobile</span><span class="o">.</span><span class="n">year</span> <span class="o"><</span> <span class="mi">2012</span><span class="p">)</span>
</pre></div>
</div>
</div></blockquote>
<p><code class="xref py py-attr docutils literal"><span class="pre"><=</span> <span class="pre">(__lte)</span></code></p>
<blockquote>
<div><div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Tesla'</span><span class="p">)</span>
<span class="n">q</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">year__lte</span><span class="o">=</span><span class="mi">2012</span><span class="p">)</span> <span class="c1"># year <= 2012</span>
<span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">Automobile</span><span class="o">.</span><span class="n">year</span> <span class="o"><=</span> <span class="mi">2012</span><span class="p">)</span>
</pre></div>
</div>
</div></blockquote>
<p><code class="xref py py-attr docutils literal"><span class="pre">CONTAINS</span> <span class="pre">(__contains)</span></code></p>
<blockquote>
<div><p>The CONTAINS operator is available for all collection types (List, Set, Map).</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Tesla'</span><span class="p">)</span>
<span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">options__contains</span><span class="o">=</span><span class="s1">'backup camera'</span><span class="p">)</span><span class="o">.</span><span class="n">allow_filtering</span><span class="p">()</span>
</pre></div>
</div>
<p>Note that we need to use allow_filtering() since the <em>options</em> column has no secondary index.</p>
</div></blockquote>
<p><code class="xref py py-attr docutils literal"><span class="pre">LIKE</span> <span class="pre">(__like)</span></code></p>
<blockquote>
<div><p>The LIKE operator is available for text columns that have a SASI secondary index.</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">q</span> <span class="o">=</span> <span class="n">Automobile</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">model__like</span><span class="o">=</span><span class="s1">'%Civic%'</span><span class="p">)</span><span class="o">.</span><span class="n">allow_filtering</span><span class="p">()</span>
</pre></div>
</div>
<p>Limitations:
- Currently, cqlengine does not support SASI index creation. To use this feature,</p>
<blockquote>
<div>you need to create the SASI index using the core driver.</div></blockquote>
<ul class="simple">
<li>Queries using LIKE must use allow_filtering() since the <em>model</em> column has no
standard secondary index. Note that the server will use the SASI index properly
when executing the query.</li>
</ul>
</div></blockquote>
</div></blockquote>
</div>
<div class="section" id="timeuuid-functions">
<h2>TimeUUID Functions<a class="headerlink" href="#timeuuid-functions" title="Permalink to this headline">¶</a></h2>
<blockquote>
<div><p>In addition to querying using regular values, there are two functions you can pass in when querying TimeUUID columns to help make filtering by them easier. Note that these functions don’t actually return a value, but instruct the cql interpreter to use the functions in it’s query.</p>
<dl class="class">
<dt id="cqlengine.queryset.MinTimeUUID">
<em class="property">class </em><code class="descclassname">cqlengine.queryset.</code><code class="descname">MinTimeUUID</code><span class="sig-paren">(</span><em>datetime</em><span class="sig-paren">)</span><a class="headerlink" href="#cqlengine.queryset.MinTimeUUID" title="Permalink to this definition">¶</a></dt>
<dd><p>returns the minimum time uuid value possible for the given datetime</p>
</dd></dl>
<dl class="class">
<dt id="cqlengine.queryset.MaxTimeUUID">
<em class="property">class </em><code class="descclassname">cqlengine.queryset.</code><code class="descname">MaxTimeUUID</code><span class="sig-paren">(</span><em>datetime</em><span class="sig-paren">)</span><a class="headerlink" href="#cqlengine.queryset.MaxTimeUUID" title="Permalink to this definition">¶</a></dt>
<dd><p>returns the maximum time uuid value possible for the given datetime</p>
</dd></dl>
<p><em>Example</em></p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">DataStream</span><span class="p">(</span><span class="n">Model</span><span class="p">):</span>
<span class="nb">id</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">UUID</span><span class="p">(</span><span class="n">partition_key</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
<span class="n">time</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">TimeUUID</span><span class="p">(</span><span class="n">primary_key</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
<span class="n">data</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">Bytes</span><span class="p">()</span>
<span class="n">min_time</span> <span class="o">=</span> <span class="n">datetime</span><span class="p">(</span><span class="mi">1982</span><span class="p">,</span> <span class="mi">1</span><span class="p">,</span> <span class="mi">1</span><span class="p">)</span>
<span class="n">max_time</span> <span class="o">=</span> <span class="n">datetime</span><span class="p">(</span><span class="mi">1982</span><span class="p">,</span> <span class="mi">3</span><span class="p">,</span> <span class="mi">9</span><span class="p">)</span>
<span class="n">DataStream</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">time__gt</span><span class="o">=</span><span class="n">functions</span><span class="o">.</span><span class="n">MinTimeUUID</span><span class="p">(</span><span class="n">min_time</span><span class="p">),</span> <span class="n">time__lt</span><span class="o">=</span><span class="n">functions</span><span class="o">.</span><span class="n">MaxTimeUUID</span><span class="p">(</span><span class="n">max_time</span><span class="p">))</span>
</pre></div>
</div>
</div></blockquote>
</div>
<div class="section" id="token-function">
<h2>Token Function<a class="headerlink" href="#token-function" title="Permalink to this headline">¶</a></h2>
<blockquote>
<div><p>Token functon may be used only on special, virtual column pk__token, representing token of partition key (it also works for composite partition keys).
Cassandra orders returned items by value of partition key token, so using cqlengine.Token we can easy paginate through all table rows.</p>
<p>See <a class="reference external" href="http://cassandra.apache.org/doc/cql3/CQL-3.0.html#tokenFun">http://cassandra.apache.org/doc/cql3/CQL-3.0.html#tokenFun</a></p>
<p><em>Example</em></p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Items</span><span class="p">(</span><span class="n">Model</span><span class="p">):</span>
<span class="nb">id</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">Text</span><span class="p">(</span><span class="n">primary_key</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
<span class="n">data</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">Bytes</span><span class="p">()</span>
<span class="n">query</span> <span class="o">=</span> <span class="n">Items</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">all</span><span class="p">()</span><span class="o">.</span><span class="n">limit</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span>
<span class="n">first_page</span> <span class="o">=</span> <span class="nb">list</span><span class="p">(</span><span class="n">query</span><span class="p">);</span>
<span class="n">last</span> <span class="o">=</span> <span class="n">first_page</span><span class="p">[</span><span class="o">-</span><span class="mi">1</span><span class="p">]</span>
<span class="n">next_page</span> <span class="o">=</span> <span class="nb">list</span><span class="p">(</span><span class="n">query</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">pk__token__gt</span><span class="o">=</span><span class="n">cqlengine</span><span class="o">.</span><span class="n">Token</span><span class="p">(</span><span class="n">last</span><span class="o">.</span><span class="n">pk</span><span class="p">)))</span>
</pre></div>
</div>
</div></blockquote>
</div>
<div class="section" id="querysets-are-immutable">
<h2>QuerySets are immutable<a class="headerlink" href="#querysets-are-immutable" title="Permalink to this headline">¶</a></h2>
<blockquote>
<div><p>When calling any method that changes a queryset, the method does not actually change the queryset object it’s called on, but returns a new queryset object with the attributes of the original queryset, plus the attributes added in the method call.</p>
<p><em>Example</em></p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="c1">#this produces 3 different querysets</span>
<span class="c1">#q does not change after it's initial definition</span>
<span class="n">q</span> <span class="o">=</span> <span class="n">Automobiles</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">year</span><span class="o">=</span><span class="mi">2012</span><span class="p">)</span>
<span class="n">tesla2012</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Tesla'</span><span class="p">)</span>
<span class="n">honda2012</span> <span class="o">=</span> <span class="n">q</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">manufacturer</span><span class="o">=</span><span class="s1">'Honda'</span><span class="p">)</span>
</pre></div>
</div>
</div></blockquote>
</div>
<div class="section" id="ordering-querysets">
<h2>Ordering QuerySets<a class="headerlink" href="#ordering-querysets" title="Permalink to this headline">¶</a></h2>
<blockquote>
<div><p>Since Cassandra is essentially a distributed hash table on steroids, the order you get records back in will not be particularly predictable.</p>
<p>However, you can set a column to order on with the <code class="docutils literal"><span class="pre">.order_by(column_name)</span></code> method.</p>
<p><em>Example</em></p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="c1">#sort ascending</span>
<span class="n">q</span> <span class="o">=</span> <span class="n">Automobiles</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">all</span><span class="p">()</span><span class="o">.</span><span class="n">order_by</span><span class="p">(</span><span class="s1">'year'</span><span class="p">)</span>
<span class="c1">#sort descending</span>
<span class="n">q</span> <span class="o">=</span> <span class="n">Automobiles</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">all</span><span class="p">()</span><span class="o">.</span><span class="n">order_by</span><span class="p">(</span><span class="s1">'-year'</span><span class="p">)</span>
</pre></div>
</div>
<p><em>Note: Cassandra only supports ordering on a clustering key. In other words, to support ordering results, your model must have more than one primary key, and you must order on a primary key, excluding the first one.</em></p>
<p><em>For instance, given our Automobile model, year is the only column we can order on.</em></p>
</div></blockquote>
</div>
<div class="section" id="values-lists">
<h2>Values Lists<a class="headerlink" href="#values-lists" title="Permalink to this headline">¶</a></h2>
<blockquote>
<div><p>There is a special QuerySet’s method <code class="docutils literal"><span class="pre">.values_list()</span></code> - when called, QuerySet returns lists of values instead of model instances. It may significantly speedup things with lower memory footprint for large responses.
Each tuple contains the value from the respective field passed into the <code class="docutils literal"><span class="pre">values_list()</span></code> call — so the first item is the first field, etc. For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">items</span> <span class="o">=</span> <span class="nb">list</span><span class="p">(</span><span class="nb">range</span><span class="p">(</span><span class="mi">20</span><span class="p">))</span>
<span class="n">random</span><span class="o">.</span><span class="n">shuffle</span><span class="p">(</span><span class="n">items</span><span class="p">)</span>
<span class="k">for</span> <span class="n">i</span> <span class="ow">in</span> <span class="n">items</span><span class="p">:</span>
<span class="n">TestModel</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="nb">id</span><span class="o">=</span><span class="mi">1</span><span class="p">,</span> <span class="n">clustering_key</span><span class="o">=</span><span class="n">i</span><span class="p">)</span>
<span class="n">values</span> <span class="o">=</span> <span class="nb">list</span><span class="p">(</span><span class="n">TestModel</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">values_list</span><span class="p">(</span><span class="s1">'clustering_key'</span><span class="p">,</span> <span class="n">flat</span><span class="o">=</span><span class="bp">True</span><span class="p">))</span>
<span class="c1"># [19L, 18L, 17L, 16L, 15L, 14L, 13L, 12L, 11L, 10L, 9L, 8L, 7L, 6L, 5L, 4L, 3L, 2L, 1L, 0L]</span>
</pre></div>
</div>
</div></blockquote>
</div>
<div class="section" id="per-query-timeouts">
<h2>Per Query Timeouts<a class="headerlink" href="#per-query-timeouts" title="Permalink to this headline">¶</a></h2>
<p>By default all queries are executed with the timeout defined in <cite>~cqlengine.connection.setup()</cite>
The examples below show how to specify a per-query timeout.
A timeout is specified in seconds and can be an int, float or None.
None means no timeout.</p>
<blockquote>
<div><div class="highlight-python"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Row</span><span class="p">(</span><span class="n">Model</span><span class="p">):</span>
<span class="nb">id</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">Integer</span><span class="p">(</span><span class="n">primary_key</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
<span class="n">name</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">Text</span><span class="p">()</span>
</pre></div>
</div>
<p>Fetch all objects with a timeout of 5 seconds</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">Row</span><span class="o">.</span><span class="n">objects</span><span class="p">()</span><span class="o">.</span><span class="n">timeout</span><span class="p">(</span><span class="mi">5</span><span class="p">)</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
</pre></div>
</div>
<p>Create a single row with a 50ms timeout</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">Row</span><span class="p">(</span><span class="nb">id</span><span class="o">=</span><span class="mi">1</span><span class="p">,</span> <span class="n">name</span><span class="o">=</span><span class="s1">'Jon'</span><span class="p">)</span><span class="o">.</span><span class="n">timeout</span><span class="p">(</span><span class="mf">0.05</span><span class="p">)</span><span class="o">.</span><span class="n">create</span><span class="p">()</span>
</pre></div>
</div>
<p>Delete a single row with no timeout</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">Row</span><span class="p">(</span><span class="nb">id</span><span class="o">=</span><span class="mi">1</span><span class="p">)</span><span class="o">.</span><span class="n">timeout</span><span class="p">(</span><span class="bp">None</span><span class="p">)</span><span class="o">.</span><span class="n">delete</span><span class="p">()</span>
</pre></div>
</div>
<p>Update a single row with no timeout</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="n">Row</span><span class="p">(</span><span class="nb">id</span><span class="o">=</span><span class="mi">1</span><span class="p">)</span><span class="o">.</span><span class="n">timeout</span><span class="p">(</span><span class="bp">None</span><span class="p">)</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">name</span><span class="o">=</span><span class="s1">'Blake'</span><span class="p">)</span>
</pre></div>
</div>
<p>Batch query timeouts</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="k">with</span> <span class="n">BatchQuery</span><span class="p">(</span><span class="n">timeout</span><span class="o">=</span><span class="mi">10</span><span class="p">)</span> <span class="k">as</span> <span class="n">b</span><span class="p">:</span>
<span class="n">Row</span><span class="p">(</span><span class="nb">id</span><span class="o">=</span><span class="mi">1</span><span class="p">,</span> <span class="n">name</span><span class="o">=</span><span class="s1">'Jon'</span><span class="p">)</span><span class="o">.</span><span class="n">create</span><span class="p">()</span>
</pre></div>
</div>
<p>NOTE: You cannot set both timeout and batch at the same time, batch will use the timeout defined in it’s constructor.
Setting the timeout on the model is meaningless and will raise an AssertionError.</p>
</div></blockquote>
</div>
<div class="section" id="default-ttl-and-per-query-ttl">
<span id="ttl-change"></span><h2>Default TTL and Per Query TTL<a class="headerlink" href="#default-ttl-and-per-query-ttl" title="Permalink to this headline">¶</a></h2>
<p>Model default TTL now relies on the <em>default_time_to_live</em> feature, introduced in Cassandra 2.0. It is not handled anymore in the CQLEngine Model (cassandra-driver >=3.6). You can set the default TTL of a table like this:</p>
<blockquote>
<div><p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">User</span><span class="p">(</span><span class="n">Model</span><span class="p">):</span>
<span class="n">__options__</span> <span class="o">=</span> <span class="p">{</span><span class="s1">'default_time_to_live'</span><span class="p">:</span> <span class="mi">20</span><span class="p">}</span>
<span class="n">user_id</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">UUID</span><span class="p">(</span><span class="n">primary_key</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
<span class="o">...</span>
</pre></div>
</div>
</div></blockquote>
<p>You can set TTL per-query if needed. Here are a some examples:</p>
<blockquote>
<div><p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">User</span><span class="p">(</span><span class="n">Model</span><span class="p">):</span>
<span class="n">__options__</span> <span class="o">=</span> <span class="p">{</span><span class="s1">'default_time_to_live'</span><span class="p">:</span> <span class="mi">20</span><span class="p">}</span>
<span class="n">user_id</span> <span class="o">=</span> <span class="n">columns</span><span class="o">.</span><span class="n">UUID</span><span class="p">(</span><span class="n">primary_key</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
<span class="o">...</span>
<span class="n">user</span> <span class="o">=</span> <span class="n">User</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="n">user_id</span><span class="o">=</span><span class="mi">1</span><span class="p">)</span> <span class="c1"># Default TTL 20 will be set automatically on the server</span>
<span class="n">user</span><span class="o">.</span><span class="n">ttl</span><span class="p">(</span><span class="mi">30</span><span class="p">)</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">age</span><span class="o">=</span><span class="mi">21</span><span class="p">)</span> <span class="c1"># Update the TTL to 30</span>
<span class="n">User</span><span class="o">.</span><span class="n">objects</span><span class="o">.</span><span class="n">ttl</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span><span class="o">.</span><span class="n">create</span><span class="p">(</span><span class="n">user_id</span><span class="o">=</span><span class="mi">1</span><span class="p">)</span> <span class="c1"># TTL 10</span>
<span class="n">User</span><span class="p">(</span><span class="n">user_id</span><span class="o">=</span><span class="mi">1</span><span class="p">,</span> <span class="n">age</span><span class="o">=</span><span class="mi">21</span><span class="p">)</span><span class="o">.</span><span class="n">ttl</span><span class="p">(</span><span class="mi">10</span><span class="p">)</span><span class="o">.</span><span class="n">save</span><span class="p">()</span> <span class="c1"># TTL 10</span>
</pre></div>
</div>
</div></blockquote>
</div>
<div class="section" id="named-tables">
<h2>Named Tables<a class="headerlink" href="#named-tables" title="Permalink to this headline">¶</a></h2>
<p>Named tables are a way of querying a table without creating an class. They’re useful for querying system tables or exploring an unfamiliar database.</p>
<blockquote>
<div><div class="highlight-python"><div class="highlight"><pre><span></span><span class="kn">from</span> <span class="nn">cassandra.cqlengine.connection</span> <span class="kn">import</span> <span class="n">setup</span>
<span class="n">setup</span><span class="p">(</span><span class="s2">"127.0.0.1"</span><span class="p">,</span> <span class="s2">"cqlengine_test"</span><span class="p">)</span>
<span class="kn">from</span> <span class="nn">cassandra.cqlengine.named</span> <span class="kn">import</span> <span class="n">NamedTable</span>
<span class="n">user</span> <span class="o">=</span> <span class="n">NamedTable</span><span class="p">(</span><span class="s2">"cqlengine_test"</span><span class="p">,</span> <span class="s2">"user"</span><span class="p">)</span>
<span class="n">user</span><span class="o">.</span><span class="n">objects</span><span class="p">()</span>
<span class="n">user</span><span class="o">.</span><span class="n">objects</span><span class="p">()[</span><span class="mi">0</span><span class="p">]</span>
<span class="c1"># {u'pk': 1, u't': datetime.datetime(2014, 6, 26, 17, 10, 31, 774000)}</span>
</pre></div>
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