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SQLAlchemy 1.2 Documentation
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Release: <span class="version-num">1.2.19</span>
| Release Date: April 15, 2019
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<h1>SQLAlchemy 1.2 Documentation</h1>
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<h1>Source code for examples.elementtree.optimized_al</h1><div class="highlight"><pre>
<span></span><span class="sd">"""Uses the same strategy as</span>
<span class="sd"> ``adjacency_list.py``, but associates each DOM row with its owning</span>
<span class="sd"> document row, so that a full document of DOM nodes can be loaded</span>
<span class="sd"> using O(1) queries - the construction of the "hierarchy" is performed</span>
<span class="sd"> after the load in a non-recursive fashion and is more</span>
<span class="sd"> efficient.</span>
<span class="sd">"""</span>
<span class="c1"># PART I - Imports/Configuration</span>
<span class="kn">import</span> <span class="nn">io</span>
<span class="kn">import</span> <span class="nn">os</span>
<span class="kn">import</span> <span class="nn">re</span>
<span class="kn">from</span> <span class="nn">xml.etree</span> <span class="k">import</span> <span class="n">ElementTree</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">and_</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">Column</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">create_engine</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">ForeignKey</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">Integer</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">MetaData</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">String</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">Table</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">Unicode</span>
<span class="kn">from</span> <span class="nn">sqlalchemy.orm</span> <span class="k">import</span> <span class="n">lazyload</span>
<span class="kn">from</span> <span class="nn">sqlalchemy.orm</span> <span class="k">import</span> <span class="n">mapper</span>
<span class="kn">from</span> <span class="nn">sqlalchemy.orm</span> <span class="k">import</span> <span class="n">relationship</span>
<span class="kn">from</span> <span class="nn">sqlalchemy.orm</span> <span class="k">import</span> <span class="n">Session</span>
<span class="n">e</span> <span class="o">=</span> <span class="n">create_engine</span><span class="p">(</span><span class="s2">"sqlite://"</span><span class="p">,</span> <span class="n">echo</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="n">meta</span> <span class="o">=</span> <span class="n">MetaData</span><span class="p">()</span>
<span class="c1"># PART II - Table Metadata</span>
<span class="c1"># stores a top level record of an XML document.</span>
<span class="n">documents</span> <span class="o">=</span> <span class="n">Table</span><span class="p">(</span>
<span class="s2">"documents"</span><span class="p">,</span>
<span class="n">meta</span><span class="p">,</span>
<span class="n">Column</span><span class="p">(</span><span class="s2">"document_id"</span><span class="p">,</span> <span class="n">Integer</span><span class="p">,</span> <span class="n">primary_key</span><span class="o">=</span><span class="kc">True</span><span class="p">),</span>
<span class="n">Column</span><span class="p">(</span><span class="s2">"filename"</span><span class="p">,</span> <span class="n">String</span><span class="p">(</span><span class="mi">30</span><span class="p">),</span> <span class="n">unique</span><span class="o">=</span><span class="kc">True</span><span class="p">),</span>
<span class="p">)</span>
<span class="c1"># stores XML nodes in an adjacency list model. This corresponds to</span>
<span class="c1"># Element and SubElement objects.</span>
<span class="n">elements</span> <span class="o">=</span> <span class="n">Table</span><span class="p">(</span>
<span class="s2">"elements"</span><span class="p">,</span>
<span class="n">meta</span><span class="p">,</span>
<span class="n">Column</span><span class="p">(</span><span class="s2">"element_id"</span><span class="p">,</span> <span class="n">Integer</span><span class="p">,</span> <span class="n">primary_key</span><span class="o">=</span><span class="kc">True</span><span class="p">),</span>
<span class="n">Column</span><span class="p">(</span><span class="s2">"parent_id"</span><span class="p">,</span> <span class="n">Integer</span><span class="p">,</span> <span class="n">ForeignKey</span><span class="p">(</span><span class="s2">"elements.element_id"</span><span class="p">)),</span>
<span class="n">Column</span><span class="p">(</span><span class="s2">"document_id"</span><span class="p">,</span> <span class="n">Integer</span><span class="p">,</span> <span class="n">ForeignKey</span><span class="p">(</span><span class="s2">"documents.document_id"</span><span class="p">)),</span>
<span class="n">Column</span><span class="p">(</span><span class="s2">"tag"</span><span class="p">,</span> <span class="n">Unicode</span><span class="p">(</span><span class="mi">30</span><span class="p">),</span> <span class="n">nullable</span><span class="o">=</span><span class="kc">False</span><span class="p">),</span>
<span class="n">Column</span><span class="p">(</span><span class="s2">"text"</span><span class="p">,</span> <span class="n">Unicode</span><span class="p">),</span>
<span class="n">Column</span><span class="p">(</span><span class="s2">"tail"</span><span class="p">,</span> <span class="n">Unicode</span><span class="p">),</span>
<span class="p">)</span>
<span class="c1"># stores attributes. This corresponds to the dictionary of attributes</span>
<span class="c1"># stored by an Element or SubElement.</span>
<span class="n">attributes</span> <span class="o">=</span> <span class="n">Table</span><span class="p">(</span>
<span class="s2">"attributes"</span><span class="p">,</span>
<span class="n">meta</span><span class="p">,</span>
<span class="n">Column</span><span class="p">(</span>
<span class="s2">"element_id"</span><span class="p">,</span>
<span class="n">Integer</span><span class="p">,</span>
<span class="n">ForeignKey</span><span class="p">(</span><span class="s2">"elements.element_id"</span><span class="p">),</span>
<span class="n">primary_key</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span>
<span class="p">),</span>
<span class="n">Column</span><span class="p">(</span><span class="s2">"name"</span><span class="p">,</span> <span class="n">Unicode</span><span class="p">(</span><span class="mi">100</span><span class="p">),</span> <span class="n">nullable</span><span class="o">=</span><span class="kc">False</span><span class="p">,</span> <span class="n">primary_key</span><span class="o">=</span><span class="kc">True</span><span class="p">),</span>
<span class="n">Column</span><span class="p">(</span><span class="s2">"value"</span><span class="p">,</span> <span class="n">Unicode</span><span class="p">(</span><span class="mi">255</span><span class="p">)),</span>
<span class="p">)</span>
<span class="n">meta</span><span class="o">.</span><span class="n">create_all</span><span class="p">(</span><span class="n">e</span><span class="p">)</span>
<span class="c1"># PART III - Model</span>
<span class="c1"># our document class. contains a string name,</span>
<span class="c1"># and the ElementTree root element.</span>
<span class="k">class</span> <span class="nc">Document</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">element</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">filename</span> <span class="o">=</span> <span class="n">name</span>
<span class="bp">self</span><span class="o">.</span><span class="n">element</span> <span class="o">=</span> <span class="n">element</span>
<span class="k">def</span> <span class="nf">__str__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="n">buf</span> <span class="o">=</span> <span class="n">io</span><span class="o">.</span><span class="n">StringIO</span><span class="p">()</span>
<span class="bp">self</span><span class="o">.</span><span class="n">element</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="n">buf</span><span class="p">)</span>
<span class="k">return</span> <span class="n">buf</span><span class="o">.</span><span class="n">getvalue</span><span class="p">()</span>
<span class="c1"># PART IV - Persistence Mapping</span>
<span class="c1"># Node class. a non-public class which will represent the DB-persisted</span>
<span class="c1"># Element/SubElement object. We cannot create mappers for ElementTree elements</span>
<span class="c1"># directly because they are at the very least not new-style classes, and also</span>
<span class="c1"># may be backed by native implementations. so here we construct an adapter.</span>
<span class="k">class</span> <span class="nc">_Node</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="k">pass</span>
<span class="c1"># Attribute class. also internal, this will represent the key/value attributes</span>
<span class="c1"># stored for a particular Node.</span>
<span class="k">class</span> <span class="nc">_Attribute</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">__init__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">name</span><span class="p">,</span> <span class="n">value</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">name</span> <span class="o">=</span> <span class="n">name</span>
<span class="bp">self</span><span class="o">.</span><span class="n">value</span> <span class="o">=</span> <span class="n">value</span>
<span class="c1"># setup mappers. Document will eagerly load a list of _Node objects.</span>
<span class="c1"># they will be ordered in primary key/insert order, so that we can reconstruct</span>
<span class="c1"># an ElementTree structure from the list.</span>
<span class="n">mapper</span><span class="p">(</span>
<span class="n">Document</span><span class="p">,</span>
<span class="n">documents</span><span class="p">,</span>
<span class="n">properties</span><span class="o">=</span><span class="p">{</span>
<span class="s2">"_nodes"</span><span class="p">:</span> <span class="n">relationship</span><span class="p">(</span>
<span class="n">_Node</span><span class="p">,</span> <span class="n">lazy</span><span class="o">=</span><span class="s2">"joined"</span><span class="p">,</span> <span class="n">cascade</span><span class="o">=</span><span class="s2">"all, delete-orphan"</span>
<span class="p">)</span>
<span class="p">},</span>
<span class="p">)</span>
<span class="c1"># the _Node objects change the way they load so that a list of _Nodes will</span>
<span class="c1"># organize themselves hierarchically using the ElementTreeMarshal. this</span>
<span class="c1"># depends on the ordering of nodes being hierarchical as well; relationship()</span>
<span class="c1"># always applies at least ROWID/primary key ordering to rows which will</span>
<span class="c1"># suffice.</span>
<span class="n">mapper</span><span class="p">(</span>
<span class="n">_Node</span><span class="p">,</span>
<span class="n">elements</span><span class="p">,</span>
<span class="n">properties</span><span class="o">=</span><span class="p">{</span>
<span class="s2">"children"</span><span class="p">:</span> <span class="n">relationship</span><span class="p">(</span>
<span class="n">_Node</span><span class="p">,</span> <span class="n">lazy</span><span class="o">=</span><span class="kc">None</span>
<span class="p">),</span> <span class="c1"># doesnt load; used only for the save relationship</span>
<span class="s2">"attributes"</span><span class="p">:</span> <span class="n">relationship</span><span class="p">(</span>
<span class="n">_Attribute</span><span class="p">,</span> <span class="n">lazy</span><span class="o">=</span><span class="s2">"joined"</span><span class="p">,</span> <span class="n">cascade</span><span class="o">=</span><span class="s2">"all, delete-orphan"</span>
<span class="p">),</span> <span class="c1"># eagerly load attributes</span>
<span class="p">},</span>
<span class="p">)</span>
<span class="n">mapper</span><span class="p">(</span><span class="n">_Attribute</span><span class="p">,</span> <span class="n">attributes</span><span class="p">)</span>
<span class="c1"># define marshalling functions that convert from _Node/_Attribute to/from</span>
<span class="c1"># ElementTree objects. this will set the ElementTree element as</span>
<span class="c1"># "document._element", and append the root _Node object to the "_nodes" mapped</span>
<span class="c1"># collection.</span>
<span class="k">class</span> <span class="nc">ElementTreeMarshal</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">__get__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">document</span><span class="p">,</span> <span class="n">owner</span><span class="p">):</span>
<span class="k">if</span> <span class="n">document</span> <span class="ow">is</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">return</span> <span class="bp">self</span>
<span class="k">if</span> <span class="nb">hasattr</span><span class="p">(</span><span class="n">document</span><span class="p">,</span> <span class="s2">"_element"</span><span class="p">):</span>
<span class="k">return</span> <span class="n">document</span><span class="o">.</span><span class="n">_element</span>
<span class="n">nodes</span> <span class="o">=</span> <span class="p">{}</span>
<span class="n">root</span> <span class="o">=</span> <span class="kc">None</span>
<span class="k">for</span> <span class="n">node</span> <span class="ow">in</span> <span class="n">document</span><span class="o">.</span><span class="n">_nodes</span><span class="p">:</span>
<span class="k">if</span> <span class="n">node</span><span class="o">.</span><span class="n">parent_id</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="n">parent</span> <span class="o">=</span> <span class="n">nodes</span><span class="p">[</span><span class="n">node</span><span class="o">.</span><span class="n">parent_id</span><span class="p">]</span>
<span class="n">elem</span> <span class="o">=</span> <span class="n">ElementTree</span><span class="o">.</span><span class="n">SubElement</span><span class="p">(</span><span class="n">parent</span><span class="p">,</span> <span class="n">node</span><span class="o">.</span><span class="n">tag</span><span class="p">)</span>
<span class="n">nodes</span><span class="p">[</span><span class="n">node</span><span class="o">.</span><span class="n">element_id</span><span class="p">]</span> <span class="o">=</span> <span class="n">elem</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">parent</span> <span class="o">=</span> <span class="kc">None</span>
<span class="n">elem</span> <span class="o">=</span> <span class="n">root</span> <span class="o">=</span> <span class="n">ElementTree</span><span class="o">.</span><span class="n">Element</span><span class="p">(</span><span class="n">node</span><span class="o">.</span><span class="n">tag</span><span class="p">)</span>
<span class="n">nodes</span><span class="p">[</span><span class="n">node</span><span class="o">.</span><span class="n">element_id</span><span class="p">]</span> <span class="o">=</span> <span class="n">root</span>
<span class="k">for</span> <span class="n">attr</span> <span class="ow">in</span> <span class="n">node</span><span class="o">.</span><span class="n">attributes</span><span class="p">:</span>
<span class="n">elem</span><span class="o">.</span><span class="n">attrib</span><span class="p">[</span><span class="n">attr</span><span class="o">.</span><span class="n">name</span><span class="p">]</span> <span class="o">=</span> <span class="n">attr</span><span class="o">.</span><span class="n">value</span>
<span class="n">elem</span><span class="o">.</span><span class="n">text</span> <span class="o">=</span> <span class="n">node</span><span class="o">.</span><span class="n">text</span>
<span class="n">elem</span><span class="o">.</span><span class="n">tail</span> <span class="o">=</span> <span class="n">node</span><span class="o">.</span><span class="n">tail</span>
<span class="n">document</span><span class="o">.</span><span class="n">_element</span> <span class="o">=</span> <span class="n">ElementTree</span><span class="o">.</span><span class="n">ElementTree</span><span class="p">(</span><span class="n">root</span><span class="p">)</span>
<span class="k">return</span> <span class="n">document</span><span class="o">.</span><span class="n">_element</span>
<span class="k">def</span> <span class="nf">__set__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">document</span><span class="p">,</span> <span class="n">element</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">traverse</span><span class="p">(</span><span class="n">node</span><span class="p">):</span>
<span class="n">n</span> <span class="o">=</span> <span class="n">_Node</span><span class="p">()</span>
<span class="n">n</span><span class="o">.</span><span class="n">tag</span> <span class="o">=</span> <span class="nb">str</span><span class="p">(</span><span class="n">node</span><span class="o">.</span><span class="n">tag</span><span class="p">)</span>
<span class="n">n</span><span class="o">.</span><span class="n">text</span> <span class="o">=</span> <span class="nb">str</span><span class="p">(</span><span class="n">node</span><span class="o">.</span><span class="n">text</span><span class="p">)</span>
<span class="n">n</span><span class="o">.</span><span class="n">tail</span> <span class="o">=</span> <span class="nb">str</span><span class="p">(</span><span class="n">node</span><span class="o">.</span><span class="n">tail</span><span class="p">)</span>
<span class="n">document</span><span class="o">.</span><span class="n">_nodes</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="n">n</span><span class="p">)</span>
<span class="n">n</span><span class="o">.</span><span class="n">children</span> <span class="o">=</span> <span class="p">[</span><span class="n">traverse</span><span class="p">(</span><span class="n">n2</span><span class="p">)</span> <span class="k">for</span> <span class="n">n2</span> <span class="ow">in</span> <span class="n">node</span><span class="p">]</span>
<span class="n">n</span><span class="o">.</span><span class="n">attributes</span> <span class="o">=</span> <span class="p">[</span>
<span class="n">_Attribute</span><span class="p">(</span><span class="nb">str</span><span class="p">(</span><span class="n">k</span><span class="p">),</span> <span class="nb">str</span><span class="p">(</span><span class="n">v</span><span class="p">))</span> <span class="k">for</span> <span class="n">k</span><span class="p">,</span> <span class="n">v</span> <span class="ow">in</span> <span class="n">node</span><span class="o">.</span><span class="n">attrib</span><span class="o">.</span><span class="n">items</span><span class="p">()</span>
<span class="p">]</span>
<span class="k">return</span> <span class="n">n</span>
<span class="n">traverse</span><span class="p">(</span><span class="n">element</span><span class="o">.</span><span class="n">getroot</span><span class="p">())</span>
<span class="n">document</span><span class="o">.</span><span class="n">_element</span> <span class="o">=</span> <span class="n">element</span>
<span class="k">def</span> <span class="nf">__delete__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">document</span><span class="p">):</span>
<span class="k">del</span> <span class="n">document</span><span class="o">.</span><span class="n">_element</span>
<span class="n">document</span><span class="o">.</span><span class="n">_nodes</span> <span class="o">=</span> <span class="p">[]</span>
<span class="c1"># override Document's "element" attribute with the marshaller.</span>
<span class="n">Document</span><span class="o">.</span><span class="n">element</span> <span class="o">=</span> <span class="n">ElementTreeMarshal</span><span class="p">()</span>
<span class="c1"># PART V - Basic Persistence Example</span>
<span class="n">line</span> <span class="o">=</span> <span class="s2">"</span><span class="se">\n</span><span class="s2">--------------------------------------------------------"</span>
<span class="c1"># save to DB</span>
<span class="n">session</span> <span class="o">=</span> <span class="n">Session</span><span class="p">(</span><span class="n">e</span><span class="p">)</span>
<span class="c1"># get ElementTree documents</span>
<span class="k">for</span> <span class="n">file</span> <span class="ow">in</span> <span class="p">(</span><span class="s2">"test.xml"</span><span class="p">,</span> <span class="s2">"test2.xml"</span><span class="p">,</span> <span class="s2">"test3.xml"</span><span class="p">):</span>
<span class="n">filename</span> <span class="o">=</span> <span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="n">os</span><span class="o">.</span><span class="n">path</span><span class="o">.</span><span class="n">dirname</span><span class="p">(</span><span class="vm">__file__</span><span class="p">),</span> <span class="n">file</span><span class="p">)</span>
<span class="n">doc</span> <span class="o">=</span> <span class="n">ElementTree</span><span class="o">.</span><span class="n">parse</span><span class="p">(</span><span class="n">filename</span><span class="p">)</span>
<span class="n">session</span><span class="o">.</span><span class="n">add</span><span class="p">(</span><span class="n">Document</span><span class="p">(</span><span class="n">file</span><span class="p">,</span> <span class="n">doc</span><span class="p">))</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"</span><span class="se">\n</span><span class="s2">Saving three documents..."</span><span class="p">,</span> <span class="n">line</span><span class="p">)</span>
<span class="n">session</span><span class="o">.</span><span class="n">commit</span><span class="p">()</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"Done."</span><span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"</span><span class="se">\n</span><span class="s2">Full text of document 'text.xml':"</span><span class="p">,</span> <span class="n">line</span><span class="p">)</span>
<span class="n">document</span> <span class="o">=</span> <span class="n">session</span><span class="o">.</span><span class="n">query</span><span class="p">(</span><span class="n">Document</span><span class="p">)</span><span class="o">.</span><span class="n">filter_by</span><span class="p">(</span><span class="n">filename</span><span class="o">=</span><span class="s2">"test.xml"</span><span class="p">)</span><span class="o">.</span><span class="n">first</span><span class="p">()</span>
<span class="nb">print</span><span class="p">(</span><span class="n">document</span><span class="p">)</span>
<span class="c1"># PART VI - Searching for Paths</span>
<span class="c1"># manually search for a document which contains "/somefile/header/field1:hi"</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"</span><span class="se">\n</span><span class="s2">Manual search for /somefile/header/field1=='hi':"</span><span class="p">,</span> <span class="n">line</span><span class="p">)</span>
<span class="n">d</span> <span class="o">=</span> <span class="p">(</span>
<span class="n">session</span><span class="o">.</span><span class="n">query</span><span class="p">(</span><span class="n">Document</span><span class="p">)</span>
<span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="s2">"_nodes"</span><span class="p">,</span> <span class="n">aliased</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">and_</span><span class="p">(</span><span class="n">_Node</span><span class="o">.</span><span class="n">parent_id</span> <span class="o">==</span> <span class="kc">None</span><span class="p">,</span> <span class="n">_Node</span><span class="o">.</span><span class="n">tag</span> <span class="o">==</span> <span class="s2">"somefile"</span><span class="p">))</span>
<span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="s2">"children"</span><span class="p">,</span> <span class="n">aliased</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span> <span class="n">from_joinpoint</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">_Node</span><span class="o">.</span><span class="n">tag</span> <span class="o">==</span> <span class="s2">"header"</span><span class="p">)</span>
<span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="s2">"children"</span><span class="p">,</span> <span class="n">aliased</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span> <span class="n">from_joinpoint</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">and_</span><span class="p">(</span><span class="n">_Node</span><span class="o">.</span><span class="n">tag</span> <span class="o">==</span> <span class="s2">"field1"</span><span class="p">,</span> <span class="n">_Node</span><span class="o">.</span><span class="n">text</span> <span class="o">==</span> <span class="s2">"hi"</span><span class="p">))</span>
<span class="o">.</span><span class="n">one</span><span class="p">()</span>
<span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="n">d</span><span class="p">)</span>
<span class="c1"># generalize the above approach into an extremely impoverished xpath function:</span>
<span class="k">def</span> <span class="nf">find_document</span><span class="p">(</span><span class="n">path</span><span class="p">,</span> <span class="n">compareto</span><span class="p">):</span>
<span class="n">j</span> <span class="o">=</span> <span class="n">documents</span>
<span class="n">prev_elements</span> <span class="o">=</span> <span class="kc">None</span>
<span class="n">query</span> <span class="o">=</span> <span class="n">session</span><span class="o">.</span><span class="n">query</span><span class="p">(</span><span class="n">Document</span><span class="p">)</span>
<span class="n">first</span> <span class="o">=</span> <span class="kc">True</span>
<span class="k">for</span> <span class="n">i</span><span class="p">,</span> <span class="n">match</span> <span class="ow">in</span> <span class="nb">enumerate</span><span class="p">(</span>
<span class="n">re</span><span class="o">.</span><span class="n">finditer</span><span class="p">(</span><span class="sa">r</span><span class="s2">"/([\w_]+)(?:\[@([\w_]+)(?:=(.*))?\])?"</span><span class="p">,</span> <span class="n">path</span><span class="p">)</span>
<span class="p">):</span>
<span class="p">(</span><span class="n">token</span><span class="p">,</span> <span class="n">attrname</span><span class="p">,</span> <span class="n">attrvalue</span><span class="p">)</span> <span class="o">=</span> <span class="n">match</span><span class="o">.</span><span class="n">group</span><span class="p">(</span><span class="mi">1</span><span class="p">,</span> <span class="mi">2</span><span class="p">,</span> <span class="mi">3</span><span class="p">)</span>
<span class="k">if</span> <span class="n">first</span><span class="p">:</span>
<span class="n">query</span> <span class="o">=</span> <span class="n">query</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="s2">"_nodes"</span><span class="p">,</span> <span class="n">aliased</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span>
<span class="n">_Node</span><span class="o">.</span><span class="n">parent_id</span> <span class="o">==</span> <span class="kc">None</span>
<span class="p">)</span>
<span class="n">first</span> <span class="o">=</span> <span class="kc">False</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">query</span> <span class="o">=</span> <span class="n">query</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="s2">"children"</span><span class="p">,</span> <span class="n">aliased</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span> <span class="n">from_joinpoint</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="n">query</span> <span class="o">=</span> <span class="n">query</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">_Node</span><span class="o">.</span><span class="n">tag</span> <span class="o">==</span> <span class="n">token</span><span class="p">)</span>
<span class="k">if</span> <span class="n">attrname</span><span class="p">:</span>
<span class="n">query</span> <span class="o">=</span> <span class="n">query</span><span class="o">.</span><span class="n">join</span><span class="p">(</span><span class="s2">"attributes"</span><span class="p">,</span> <span class="n">aliased</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span> <span class="n">from_joinpoint</span><span class="o">=</span><span class="kc">True</span><span class="p">)</span>
<span class="k">if</span> <span class="n">attrvalue</span><span class="p">:</span>
<span class="n">query</span> <span class="o">=</span> <span class="n">query</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span>
<span class="n">and_</span><span class="p">(</span>
<span class="n">_Attribute</span><span class="o">.</span><span class="n">name</span> <span class="o">==</span> <span class="n">attrname</span><span class="p">,</span>
<span class="n">_Attribute</span><span class="o">.</span><span class="n">value</span> <span class="o">==</span> <span class="n">attrvalue</span><span class="p">,</span>
<span class="p">)</span>
<span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="n">query</span> <span class="o">=</span> <span class="n">query</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">_Attribute</span><span class="o">.</span><span class="n">name</span> <span class="o">==</span> <span class="n">attrname</span><span class="p">)</span>
<span class="k">return</span> <span class="p">(</span>
<span class="n">query</span><span class="o">.</span><span class="n">options</span><span class="p">(</span><span class="n">lazyload</span><span class="p">(</span><span class="s2">"_nodes"</span><span class="p">))</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">_Node</span><span class="o">.</span><span class="n">text</span> <span class="o">==</span> <span class="n">compareto</span><span class="p">)</span><span class="o">.</span><span class="n">all</span><span class="p">()</span>
<span class="p">)</span>
<span class="k">for</span> <span class="n">path</span><span class="p">,</span> <span class="n">compareto</span> <span class="ow">in</span> <span class="p">(</span>
<span class="p">(</span><span class="s2">"/somefile/header/field1"</span><span class="p">,</span> <span class="s2">"hi"</span><span class="p">),</span>
<span class="p">(</span><span class="s2">"/somefile/field1"</span><span class="p">,</span> <span class="s2">"hi"</span><span class="p">),</span>
<span class="p">(</span><span class="s2">"/somefile/header/field2"</span><span class="p">,</span> <span class="s2">"there"</span><span class="p">),</span>
<span class="p">(</span><span class="s2">"/somefile/header/field2[@attr=foo]"</span><span class="p">,</span> <span class="s2">"there"</span><span class="p">),</span>
<span class="p">):</span>
<span class="nb">print</span><span class="p">(</span><span class="s2">"</span><span class="se">\n</span><span class="s2">Documents containing '</span><span class="si">%s</span><span class="s2">=</span><span class="si">%s</span><span class="s2">':"</span> <span class="o">%</span> <span class="p">(</span><span class="n">path</span><span class="p">,</span> <span class="n">compareto</span><span class="p">),</span> <span class="n">line</span><span class="p">)</span>
<span class="nb">print</span><span class="p">([</span><span class="n">d</span><span class="o">.</span><span class="n">filename</span> <span class="k">for</span> <span class="n">d</span> <span class="ow">in</span> <span class="n">find_document</span><span class="p">(</span><span class="n">path</span><span class="p">,</span> <span class="n">compareto</span><span class="p">)])</span></pre></div>
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distrib
>
Mageia
>
7
>
armv7hl
>
media
>
core-updates
>
by-pkgid
>
b0b6ffab06cbeede296e36ce94734bf8
>
files
>
664
