<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>
examples.postgis.postgis
—
SQLAlchemy 1.2 Documentation
</title>
<!-- begin iterate through site-imported + sphinx environment css_files -->
<link rel="stylesheet" href="../../../_static/pygments.css" type="text/css" />
<link rel="stylesheet" href="../../../_static/docs.css" type="text/css" />
<link rel="stylesheet" href="../../../_static/changelog.css" type="text/css" />
<link rel="stylesheet" href="../../../_static/sphinx_paramlinks.css" type="text/css" />
<!-- end iterate through site-imported + sphinx environment css_files -->
<!-- begin layout.mako headers -->
<link rel="index" title="Index" href="../../../genindex.html" />
<link rel="search" title="Search" href="../../../search.html" />
<link rel="copyright" title="Copyright" href="../../../copyright.html" />
<link rel="top" title="SQLAlchemy 1.2 Documentation" href="../../../index.html" />
<link rel="up" title="Module code" href="../../index.html" />
<!-- end layout.mako headers -->
</head>
<body>
<div id="docs-container">
<div id="docs-top-navigation-container" class="body-background">
<div id="docs-header">
<div id="docs-version-header">
Release: <span class="version-num">1.2.19</span>
| Release Date: April 15, 2019
</div>
<h1>SQLAlchemy 1.2 Documentation</h1>
</div>
</div>
<div id="docs-body-container">
<div id="fixed-sidebar" class="">
<div id="index-nav">
<form class="search" action="../../../search.html" method="get">
<label>
Search terms:
<input type="text" placeholder="search..." name="q" size="12" />
</label>
<input type="submit" value="Search" />
<input type="hidden" name="check_keywords" value="yes" />
<input type="hidden" name="area" value="default" />
</form>
<p>
<a href="../../../contents.html">Contents</a> |
<a href="../../../genindex.html">Index</a>
</p>
</div>
</div>
<div id="docs-body" class="" >
<h1>Source code for examples.postgis.postgis</h1><div class="highlight"><pre>
<span></span><span class="kn">import</span> <span class="nn">binascii</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="n">event</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.sql</span> <span class="k">import</span> <span class="n">expression</span>
<span class="kn">from</span> <span class="nn">sqlalchemy.sql</span> <span class="k">import</span> <span class="n">type_coerce</span>
<span class="kn">from</span> <span class="nn">sqlalchemy.types</span> <span class="k">import</span> <span class="n">UserDefinedType</span>
<span class="c1"># Python datatypes</span>
<span class="k">class</span> <span class="nc">GisElement</span><span class="p">(</span><span class="nb">object</span><span class="p">):</span>
<span class="sd">"""Represents a geometry value."""</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="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">desc</span>
<span class="k">def</span> <span class="nf">__repr__</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="s2">"<</span><span class="si">%s</span><span class="s2"> at 0x</span><span class="si">%x</span><span class="s2">; </span><span class="si">%r</span><span class="s2">>"</span> <span class="o">%</span> <span class="p">(</span>
<span class="bp">self</span><span class="o">.</span><span class="vm">__class__</span><span class="o">.</span><span class="vm">__name__</span><span class="p">,</span>
<span class="nb">id</span><span class="p">(</span><span class="bp">self</span><span class="p">),</span>
<span class="bp">self</span><span class="o">.</span><span class="n">desc</span><span class="p">,</span>
<span class="p">)</span>
<span class="k">class</span> <span class="nc">BinaryGisElement</span><span class="p">(</span><span class="n">GisElement</span><span class="p">,</span> <span class="n">expression</span><span class="o">.</span><span class="n">Function</span><span class="p">):</span>
<span class="sd">"""Represents a Geometry value expressed as binary."""</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">data</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">data</span> <span class="o">=</span> <span class="n">data</span>
<span class="n">expression</span><span class="o">.</span><span class="n">Function</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span>
<span class="bp">self</span><span class="p">,</span> <span class="s2">"ST_GeomFromEWKB"</span><span class="p">,</span> <span class="n">data</span><span class="p">,</span> <span class="n">type_</span><span class="o">=</span><span class="n">Geometry</span><span class="p">(</span><span class="n">coerce_</span><span class="o">=</span><span class="s2">"binary"</span><span class="p">)</span>
<span class="p">)</span>
<span class="nd">@property</span>
<span class="k">def</span> <span class="nf">desc</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">as_hex</span>
<span class="nd">@property</span>
<span class="k">def</span> <span class="nf">as_hex</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="n">binascii</span><span class="o">.</span><span class="n">hexlify</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">data</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">TextualGisElement</span><span class="p">(</span><span class="n">GisElement</span><span class="p">,</span> <span class="n">expression</span><span class="o">.</span><span class="n">Function</span><span class="p">):</span>
<span class="sd">"""Represents a Geometry value expressed as text."""</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">desc</span><span class="p">,</span> <span class="n">srid</span><span class="o">=-</span><span class="mi">1</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">desc</span> <span class="o">=</span> <span class="n">desc</span>
<span class="n">expression</span><span class="o">.</span><span class="n">Function</span><span class="o">.</span><span class="fm">__init__</span><span class="p">(</span>
<span class="bp">self</span><span class="p">,</span> <span class="s2">"ST_GeomFromText"</span><span class="p">,</span> <span class="n">desc</span><span class="p">,</span> <span class="n">srid</span><span class="p">,</span> <span class="n">type_</span><span class="o">=</span><span class="n">Geometry</span>
<span class="p">)</span>
<span class="c1"># SQL datatypes.</span>
<span class="k">class</span> <span class="nc">Geometry</span><span class="p">(</span><span class="n">UserDefinedType</span><span class="p">):</span>
<span class="sd">"""Base PostGIS Geometry column type."""</span>
<span class="n">name</span> <span class="o">=</span> <span class="s2">"GEOMETRY"</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">dimension</span><span class="o">=</span><span class="kc">None</span><span class="p">,</span> <span class="n">srid</span><span class="o">=-</span><span class="mi">1</span><span class="p">,</span> <span class="n">coerce_</span><span class="o">=</span><span class="s2">"text"</span><span class="p">):</span>
<span class="bp">self</span><span class="o">.</span><span class="n">dimension</span> <span class="o">=</span> <span class="n">dimension</span>
<span class="bp">self</span><span class="o">.</span><span class="n">srid</span> <span class="o">=</span> <span class="n">srid</span>
<span class="bp">self</span><span class="o">.</span><span class="n">coerce</span> <span class="o">=</span> <span class="n">coerce_</span>
<span class="k">class</span> <span class="nc">comparator_factory</span><span class="p">(</span><span class="n">UserDefinedType</span><span class="o">.</span><span class="n">Comparator</span><span class="p">):</span>
<span class="sd">"""Define custom operations for geometry types."""</span>
<span class="c1"># override the __eq__() operator</span>
<span class="k">def</span> <span class="nf">__eq__</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">other</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">op</span><span class="p">(</span><span class="s2">"~="</span><span class="p">)(</span><span class="n">other</span><span class="p">)</span>
<span class="c1"># add a custom operator</span>
<span class="k">def</span> <span class="nf">intersects</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">other</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">op</span><span class="p">(</span><span class="s2">"&&"</span><span class="p">)(</span><span class="n">other</span><span class="p">)</span>
<span class="c1"># any number of GIS operators can be overridden/added here</span>
<span class="c1"># using the techniques above.</span>
<span class="k">def</span> <span class="nf">_coerce_compared_value</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">op</span><span class="p">,</span> <span class="n">value</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span>
<span class="k">def</span> <span class="nf">get_col_spec</span><span class="p">(</span><span class="bp">self</span><span class="p">):</span>
<span class="k">return</span> <span class="bp">self</span><span class="o">.</span><span class="n">name</span>
<span class="k">def</span> <span class="nf">bind_expression</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">bindvalue</span><span class="p">):</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">coerce</span> <span class="o">==</span> <span class="s2">"text"</span><span class="p">:</span>
<span class="k">return</span> <span class="n">TextualGisElement</span><span class="p">(</span><span class="n">bindvalue</span><span class="p">)</span>
<span class="k">elif</span> <span class="bp">self</span><span class="o">.</span><span class="n">coerce</span> <span class="o">==</span> <span class="s2">"binary"</span><span class="p">:</span>
<span class="k">return</span> <span class="n">BinaryGisElement</span><span class="p">(</span><span class="n">bindvalue</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">assert</span> <span class="kc">False</span>
<span class="k">def</span> <span class="nf">column_expression</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">col</span><span class="p">):</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">coerce</span> <span class="o">==</span> <span class="s2">"text"</span><span class="p">:</span>
<span class="k">return</span> <span class="n">func</span><span class="o">.</span><span class="n">ST_AsText</span><span class="p">(</span><span class="n">col</span><span class="p">,</span> <span class="n">type_</span><span class="o">=</span><span class="bp">self</span><span class="p">)</span>
<span class="k">elif</span> <span class="bp">self</span><span class="o">.</span><span class="n">coerce</span> <span class="o">==</span> <span class="s2">"binary"</span><span class="p">:</span>
<span class="k">return</span> <span class="n">func</span><span class="o">.</span><span class="n">ST_AsBinary</span><span class="p">(</span><span class="n">col</span><span class="p">,</span> <span class="n">type_</span><span class="o">=</span><span class="bp">self</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">assert</span> <span class="kc">False</span>
<span class="k">def</span> <span class="nf">bind_processor</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">dialect</span><span class="p">):</span>
<span class="k">def</span> <span class="nf">process</span><span class="p">(</span><span class="n">value</span><span class="p">):</span>
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">GisElement</span><span class="p">):</span>
<span class="k">return</span> <span class="n">value</span><span class="o">.</span><span class="n">desc</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">return</span> <span class="n">value</span>
<span class="k">return</span> <span class="n">process</span>
<span class="k">def</span> <span class="nf">result_processor</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">dialect</span><span class="p">,</span> <span class="n">coltype</span><span class="p">):</span>
<span class="k">if</span> <span class="bp">self</span><span class="o">.</span><span class="n">coerce</span> <span class="o">==</span> <span class="s2">"text"</span><span class="p">:</span>
<span class="n">fac</span> <span class="o">=</span> <span class="n">TextualGisElement</span>
<span class="k">elif</span> <span class="bp">self</span><span class="o">.</span><span class="n">coerce</span> <span class="o">==</span> <span class="s2">"binary"</span><span class="p">:</span>
<span class="n">fac</span> <span class="o">=</span> <span class="n">BinaryGisElement</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">assert</span> <span class="kc">False</span>
<span class="k">def</span> <span class="nf">process</span><span class="p">(</span><span class="n">value</span><span class="p">):</span>
<span class="k">if</span> <span class="n">value</span> <span class="ow">is</span> <span class="ow">not</span> <span class="kc">None</span><span class="p">:</span>
<span class="k">return</span> <span class="n">fac</span><span class="p">(</span><span class="n">value</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">return</span> <span class="n">value</span>
<span class="k">return</span> <span class="n">process</span>
<span class="k">def</span> <span class="nf">adapt</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">impltype</span><span class="p">):</span>
<span class="k">return</span> <span class="n">impltype</span><span class="p">(</span>
<span class="n">dimension</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">dimension</span><span class="p">,</span> <span class="n">srid</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">srid</span><span class="p">,</span> <span class="n">coerce_</span><span class="o">=</span><span class="bp">self</span><span class="o">.</span><span class="n">coerce</span>
<span class="p">)</span>
<span class="c1"># other datatypes can be added as needed.</span>
<span class="k">class</span> <span class="nc">Point</span><span class="p">(</span><span class="n">Geometry</span><span class="p">):</span>
<span class="n">name</span> <span class="o">=</span> <span class="s2">"POINT"</span>
<span class="k">class</span> <span class="nc">Curve</span><span class="p">(</span><span class="n">Geometry</span><span class="p">):</span>
<span class="n">name</span> <span class="o">=</span> <span class="s2">"CURVE"</span>
<span class="k">class</span> <span class="nc">LineString</span><span class="p">(</span><span class="n">Curve</span><span class="p">):</span>
<span class="n">name</span> <span class="o">=</span> <span class="s2">"LINESTRING"</span>
<span class="c1"># ... etc.</span>
<span class="c1"># DDL integration</span>
<span class="c1"># PostGIS historically has required AddGeometryColumn/DropGeometryColumn</span>
<span class="c1"># and other management methods in order to create PostGIS columns. Newer</span>
<span class="c1"># versions don't appear to require these special steps anymore. However,</span>
<span class="c1"># here we illustrate how to set up these features in any case.</span>
<span class="k">def</span> <span class="nf">setup_ddl_events</span><span class="p">():</span>
<span class="nd">@event</span><span class="o">.</span><span class="n">listens_for</span><span class="p">(</span><span class="n">Table</span><span class="p">,</span> <span class="s2">"before_create"</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">before_create</span><span class="p">(</span><span class="n">target</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="o">**</span><span class="n">kw</span><span class="p">):</span>
<span class="n">dispatch</span><span class="p">(</span><span class="s2">"before-create"</span><span class="p">,</span> <span class="n">target</span><span class="p">,</span> <span class="n">connection</span><span class="p">)</span>
<span class="nd">@event</span><span class="o">.</span><span class="n">listens_for</span><span class="p">(</span><span class="n">Table</span><span class="p">,</span> <span class="s2">"after_create"</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">after_create</span><span class="p">(</span><span class="n">target</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="o">**</span><span class="n">kw</span><span class="p">):</span>
<span class="n">dispatch</span><span class="p">(</span><span class="s2">"after-create"</span><span class="p">,</span> <span class="n">target</span><span class="p">,</span> <span class="n">connection</span><span class="p">)</span>
<span class="nd">@event</span><span class="o">.</span><span class="n">listens_for</span><span class="p">(</span><span class="n">Table</span><span class="p">,</span> <span class="s2">"before_drop"</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">before_drop</span><span class="p">(</span><span class="n">target</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="o">**</span><span class="n">kw</span><span class="p">):</span>
<span class="n">dispatch</span><span class="p">(</span><span class="s2">"before-drop"</span><span class="p">,</span> <span class="n">target</span><span class="p">,</span> <span class="n">connection</span><span class="p">)</span>
<span class="nd">@event</span><span class="o">.</span><span class="n">listens_for</span><span class="p">(</span><span class="n">Table</span><span class="p">,</span> <span class="s2">"after_drop"</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">after_drop</span><span class="p">(</span><span class="n">target</span><span class="p">,</span> <span class="n">connection</span><span class="p">,</span> <span class="o">**</span><span class="n">kw</span><span class="p">):</span>
<span class="n">dispatch</span><span class="p">(</span><span class="s2">"after-drop"</span><span class="p">,</span> <span class="n">target</span><span class="p">,</span> <span class="n">connection</span><span class="p">)</span>
<span class="k">def</span> <span class="nf">dispatch</span><span class="p">(</span><span class="n">event</span><span class="p">,</span> <span class="n">table</span><span class="p">,</span> <span class="n">bind</span><span class="p">):</span>
<span class="k">if</span> <span class="n">event</span> <span class="ow">in</span> <span class="p">(</span><span class="s2">"before-create"</span><span class="p">,</span> <span class="s2">"before-drop"</span><span class="p">):</span>
<span class="n">regular_cols</span> <span class="o">=</span> <span class="p">[</span>
<span class="n">c</span> <span class="k">for</span> <span class="n">c</span> <span class="ow">in</span> <span class="n">table</span><span class="o">.</span><span class="n">c</span> <span class="k">if</span> <span class="ow">not</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">c</span><span class="o">.</span><span class="n">type</span><span class="p">,</span> <span class="n">Geometry</span><span class="p">)</span>
<span class="p">]</span>
<span class="n">gis_cols</span> <span class="o">=</span> <span class="nb">set</span><span class="p">(</span><span class="n">table</span><span class="o">.</span><span class="n">c</span><span class="p">)</span><span class="o">.</span><span class="n">difference</span><span class="p">(</span><span class="n">regular_cols</span><span class="p">)</span>
<span class="n">table</span><span class="o">.</span><span class="n">info</span><span class="p">[</span><span class="s2">"_saved_columns"</span><span class="p">]</span> <span class="o">=</span> <span class="n">table</span><span class="o">.</span><span class="n">c</span>
<span class="c1"># temporarily patch a set of columns not including the</span>
<span class="c1"># Geometry columns</span>
<span class="n">table</span><span class="o">.</span><span class="n">columns</span> <span class="o">=</span> <span class="n">expression</span><span class="o">.</span><span class="n">ColumnCollection</span><span class="p">(</span><span class="o">*</span><span class="n">regular_cols</span><span class="p">)</span>
<span class="k">if</span> <span class="n">event</span> <span class="o">==</span> <span class="s2">"before-drop"</span><span class="p">:</span>
<span class="k">for</span> <span class="n">c</span> <span class="ow">in</span> <span class="n">gis_cols</span><span class="p">:</span>
<span class="n">bind</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span>
<span class="n">select</span><span class="p">(</span>
<span class="p">[</span>
<span class="n">func</span><span class="o">.</span><span class="n">DropGeometryColumn</span><span class="p">(</span>
<span class="s2">"public"</span><span class="p">,</span> <span class="n">table</span><span class="o">.</span><span class="n">name</span><span class="p">,</span> <span class="n">c</span><span class="o">.</span><span class="n">name</span>
<span class="p">)</span>
<span class="p">],</span>
<span class="n">autocommit</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span>
<span class="p">)</span>
<span class="p">)</span>
<span class="k">elif</span> <span class="n">event</span> <span class="o">==</span> <span class="s2">"after-create"</span><span class="p">:</span>
<span class="n">table</span><span class="o">.</span><span class="n">columns</span> <span class="o">=</span> <span class="n">table</span><span class="o">.</span><span class="n">info</span><span class="o">.</span><span class="n">pop</span><span class="p">(</span><span class="s2">"_saved_columns"</span><span class="p">)</span>
<span class="k">for</span> <span class="n">c</span> <span class="ow">in</span> <span class="n">table</span><span class="o">.</span><span class="n">c</span><span class="p">:</span>
<span class="k">if</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">c</span><span class="o">.</span><span class="n">type</span><span class="p">,</span> <span class="n">Geometry</span><span class="p">):</span>
<span class="n">bind</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span>
<span class="n">select</span><span class="p">(</span>
<span class="p">[</span>
<span class="n">func</span><span class="o">.</span><span class="n">AddGeometryColumn</span><span class="p">(</span>
<span class="n">table</span><span class="o">.</span><span class="n">name</span><span class="p">,</span>
<span class="n">c</span><span class="o">.</span><span class="n">name</span><span class="p">,</span>
<span class="n">c</span><span class="o">.</span><span class="n">type</span><span class="o">.</span><span class="n">srid</span><span class="p">,</span>
<span class="n">c</span><span class="o">.</span><span class="n">type</span><span class="o">.</span><span class="n">name</span><span class="p">,</span>
<span class="n">c</span><span class="o">.</span><span class="n">type</span><span class="o">.</span><span class="n">dimension</span><span class="p">,</span>
<span class="p">)</span>
<span class="p">],</span>
<span class="n">autocommit</span><span class="o">=</span><span class="kc">True</span><span class="p">,</span>
<span class="p">)</span>
<span class="p">)</span>
<span class="k">elif</span> <span class="n">event</span> <span class="o">==</span> <span class="s2">"after-drop"</span><span class="p">:</span>
<span class="n">table</span><span class="o">.</span><span class="n">columns</span> <span class="o">=</span> <span class="n">table</span><span class="o">.</span><span class="n">info</span><span class="o">.</span><span class="n">pop</span><span class="p">(</span><span class="s2">"_saved_columns"</span><span class="p">)</span>
<span class="n">setup_ddl_events</span><span class="p">()</span>
<span class="c1"># illustrate usage</span>
<span class="k">if</span> <span class="vm">__name__</span> <span class="o">==</span> <span class="s2">"__main__"</span><span class="p">:</span>
<span class="kn">from</span> <span class="nn">sqlalchemy</span> <span class="k">import</span> <span class="p">(</span>
<span class="n">create_engine</span><span class="p">,</span>
<span class="n">MetaData</span><span class="p">,</span>
<span class="n">Column</span><span class="p">,</span>
<span class="n">Integer</span><span class="p">,</span>
<span class="n">String</span><span class="p">,</span>
<span class="n">func</span><span class="p">,</span>
<span class="n">select</span><span class="p">,</span>
<span class="p">)</span>
<span class="kn">from</span> <span class="nn">sqlalchemy.orm</span> <span class="k">import</span> <span class="n">sessionmaker</span>
<span class="kn">from</span> <span class="nn">sqlalchemy.ext.declarative</span> <span class="k">import</span> <span class="n">declarative_base</span>
<span class="n">engine</span> <span class="o">=</span> <span class="n">create_engine</span><span class="p">(</span>
<span class="s2">"postgresql://scott:tiger@localhost/test"</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">metadata</span> <span class="o">=</span> <span class="n">MetaData</span><span class="p">(</span><span class="n">engine</span><span class="p">)</span>
<span class="n">Base</span> <span class="o">=</span> <span class="n">declarative_base</span><span class="p">(</span><span class="n">metadata</span><span class="o">=</span><span class="n">metadata</span><span class="p">)</span>
<span class="k">class</span> <span class="nc">Road</span><span class="p">(</span><span class="n">Base</span><span class="p">):</span>
<span class="n">__tablename__</span> <span class="o">=</span> <span class="s2">"roads"</span>
<span class="n">road_id</span> <span class="o">=</span> <span class="n">Column</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">road_name</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">String</span><span class="p">)</span>
<span class="n">road_geom</span> <span class="o">=</span> <span class="n">Column</span><span class="p">(</span><span class="n">Geometry</span><span class="p">(</span><span class="mi">2</span><span class="p">))</span>
<span class="n">metadata</span><span class="o">.</span><span class="n">drop_all</span><span class="p">()</span>
<span class="n">metadata</span><span class="o">.</span><span class="n">create_all</span><span class="p">()</span>
<span class="n">session</span> <span class="o">=</span> <span class="n">sessionmaker</span><span class="p">(</span><span class="n">bind</span><span class="o">=</span><span class="n">engine</span><span class="p">)()</span>
<span class="c1"># Add objects. We can use strings...</span>
<span class="n">session</span><span class="o">.</span><span class="n">add_all</span><span class="p">(</span>
<span class="p">[</span>
<span class="n">Road</span><span class="p">(</span>
<span class="n">road_name</span><span class="o">=</span><span class="s2">"Jeff Rd"</span><span class="p">,</span>
<span class="n">road_geom</span><span class="o">=</span><span class="s2">"LINESTRING(191232 243118,191108 243242)"</span><span class="p">,</span>
<span class="p">),</span>
<span class="n">Road</span><span class="p">(</span>
<span class="n">road_name</span><span class="o">=</span><span class="s2">"Geordie Rd"</span><span class="p">,</span>
<span class="n">road_geom</span><span class="o">=</span><span class="s2">"LINESTRING(189141 244158,189265 244817)"</span><span class="p">,</span>
<span class="p">),</span>
<span class="n">Road</span><span class="p">(</span>
<span class="n">road_name</span><span class="o">=</span><span class="s2">"Paul St"</span><span class="p">,</span>
<span class="n">road_geom</span><span class="o">=</span><span class="s2">"LINESTRING(192783 228138,192612 229814)"</span><span class="p">,</span>
<span class="p">),</span>
<span class="n">Road</span><span class="p">(</span>
<span class="n">road_name</span><span class="o">=</span><span class="s2">"Graeme Ave"</span><span class="p">,</span>
<span class="n">road_geom</span><span class="o">=</span><span class="s2">"LINESTRING(189412 252431,189631 259122)"</span><span class="p">,</span>
<span class="p">),</span>
<span class="n">Road</span><span class="p">(</span>
<span class="n">road_name</span><span class="o">=</span><span class="s2">"Phil Tce"</span><span class="p">,</span>
<span class="n">road_geom</span><span class="o">=</span><span class="s2">"LINESTRING(190131 224148,190871 228134)"</span><span class="p">,</span>
<span class="p">),</span>
<span class="p">]</span>
<span class="p">)</span>
<span class="c1"># or use an explicit TextualGisElement</span>
<span class="c1"># (similar to saying func.GeomFromText())</span>
<span class="n">r</span> <span class="o">=</span> <span class="n">Road</span><span class="p">(</span>
<span class="n">road_name</span><span class="o">=</span><span class="s2">"Dave Cres"</span><span class="p">,</span>
<span class="n">road_geom</span><span class="o">=</span><span class="n">TextualGisElement</span><span class="p">(</span>
<span class="s2">"LINESTRING(198231 263418,198213 268322)"</span><span class="p">,</span> <span class="o">-</span><span class="mi">1</span>
<span class="p">),</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">r</span><span class="p">)</span>
<span class="c1"># pre flush, the TextualGisElement represents the string we sent.</span>
<span class="k">assert</span> <span class="nb">str</span><span class="p">(</span><span class="n">r</span><span class="o">.</span><span class="n">road_geom</span><span class="p">)</span> <span class="o">==</span> <span class="s2">"LINESTRING(198231 263418,198213 268322)"</span>
<span class="n">session</span><span class="o">.</span><span class="n">commit</span><span class="p">()</span>
<span class="c1"># after flush and/or commit, all the TextualGisElements</span>
<span class="c1"># become PersistentGisElements.</span>
<span class="k">assert</span> <span class="nb">str</span><span class="p">(</span><span class="n">r</span><span class="o">.</span><span class="n">road_geom</span><span class="p">)</span> <span class="o">==</span> <span class="s2">"LINESTRING(198231 263418,198213 268322)"</span>
<span class="n">r1</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">Road</span><span class="p">)</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">Road</span><span class="o">.</span><span class="n">road_name</span> <span class="o">==</span> <span class="s2">"Graeme Ave"</span><span class="p">)</span><span class="o">.</span><span class="n">one</span><span class="p">()</span>
<span class="c1"># illustrate the overridden __eq__() operator.</span>
<span class="c1"># strings come in as TextualGisElements</span>
<span class="n">r2</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">Road</span><span class="p">)</span>
<span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">Road</span><span class="o">.</span><span class="n">road_geom</span> <span class="o">==</span> <span class="s2">"LINESTRING(189412 252431,189631 259122)"</span><span class="p">)</span>
<span class="o">.</span><span class="n">one</span><span class="p">()</span>
<span class="p">)</span>
<span class="n">r3</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">Road</span><span class="p">)</span><span class="o">.</span><span class="n">filter</span><span class="p">(</span><span class="n">Road</span><span class="o">.</span><span class="n">road_geom</span> <span class="o">==</span> <span class="n">r1</span><span class="o">.</span><span class="n">road_geom</span><span class="p">)</span><span class="o">.</span><span class="n">one</span><span class="p">()</span>
<span class="k">assert</span> <span class="n">r1</span> <span class="ow">is</span> <span class="n">r2</span> <span class="ow">is</span> <span class="n">r3</span>
<span class="c1"># core usage just fine:</span>
<span class="n">road_table</span> <span class="o">=</span> <span class="n">Road</span><span class="o">.</span><span class="n">__table__</span>
<span class="n">stmt</span> <span class="o">=</span> <span class="n">select</span><span class="p">([</span><span class="n">road_table</span><span class="p">])</span><span class="o">.</span><span class="n">where</span><span class="p">(</span>
<span class="n">road_table</span><span class="o">.</span><span class="n">c</span><span class="o">.</span><span class="n">road_geom</span><span class="o">.</span><span class="n">intersects</span><span class="p">(</span><span class="n">r1</span><span class="o">.</span><span class="n">road_geom</span><span class="p">)</span>
<span class="p">)</span>
<span class="nb">print</span><span class="p">(</span><span class="n">session</span><span class="o">.</span><span class="n">execute</span><span class="p">(</span><span class="n">stmt</span><span class="p">)</span><span class="o">.</span><span class="n">fetchall</span><span class="p">())</span>
<span class="c1"># TODO: for some reason the auto-generated labels have the internal</span>
<span class="c1"># replacement strings exposed, even though PG doesn't complain</span>
<span class="c1"># look up the hex binary version, using SQLAlchemy casts</span>
<span class="n">as_binary</span> <span class="o">=</span> <span class="n">session</span><span class="o">.</span><span class="n">scalar</span><span class="p">(</span>
<span class="n">select</span><span class="p">([</span><span class="n">type_coerce</span><span class="p">(</span><span class="n">r</span><span class="o">.</span><span class="n">road_geom</span><span class="p">,</span> <span class="n">Geometry</span><span class="p">(</span><span class="n">coerce_</span><span class="o">=</span><span class="s2">"binary"</span><span class="p">))])</span>
<span class="p">)</span>
<span class="k">assert</span> <span class="n">as_binary</span><span class="o">.</span><span class="n">as_hex</span> <span class="o">==</span> <span class="p">(</span>
<span class="s2">"01020000000200000000000000b832084100000000"</span>
<span class="s2">"e813104100000000283208410000000088601041"</span>
<span class="p">)</span>
<span class="c1"># back again, same method !</span>
<span class="n">as_text</span> <span class="o">=</span> <span class="n">session</span><span class="o">.</span><span class="n">scalar</span><span class="p">(</span>
<span class="n">select</span><span class="p">([</span><span class="n">type_coerce</span><span class="p">(</span><span class="n">as_binary</span><span class="p">,</span> <span class="n">Geometry</span><span class="p">(</span><span class="n">coerce_</span><span class="o">=</span><span class="s2">"text"</span><span class="p">))])</span>
<span class="p">)</span>
<span class="k">assert</span> <span class="n">as_text</span><span class="o">.</span><span class="n">desc</span> <span class="o">==</span> <span class="s2">"LINESTRING(198231 263418,198213 268322)"</span>
<span class="n">session</span><span class="o">.</span><span class="n">rollback</span><span class="p">()</span>
<span class="n">metadata</span><span class="o">.</span><span class="n">drop_all</span><span class="p">()</span></pre></div>
</div>
</div>
<div id="docs-bottom-navigation" class="docs-navigation-links">
<div id="docs-copyright">
© <a href="../../../copyright.html">Copyright</a> 2007-2019, the SQLAlchemy authors and contributors.
Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 2.0.1.
</div>
</div>
</div>
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: '../../../',
VERSION: '1.2.19',
COLLAPSE_MODINDEX: false,
FILE_SUFFIX: '.html'
};
</script>
<script type="text/javascript" id="documentation_options" data-url_root="../../../" src="../../../_static/documentation_options.js"></script>
<!-- begin iterate through sphinx environment script_files -->
<script type="text/javascript" src="../../../_static/jquery.js"></script>
<script type="text/javascript" src="../../../_static/underscore.js"></script>
<script type="text/javascript" src="../../../_static/doctools.js"></script>
<script type="text/javascript" src="../../../_static/language_data.js"></script>
<!-- end iterate through sphinx environment script_files -->
<script type="text/javascript" src="../../../_static/detectmobile.js"></script>
<script type="text/javascript" src="../../../_static/init.js"></script>
</body>
</html>
distrib
>
Mageia
>
7
>
armv7hl
>
media
>
core-updates
>
by-pkgid
>
b0b6ffab06cbeede296e36ce94734bf8
>
files
>
694
