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<div class="section" id="upgrading-from-rdflib-version-3-x-to-4-x">
<h1>Upgrading from RDFLib version 3.X to 4.X<a class="headerlink" href="#upgrading-from-rdflib-version-3-x-to-4-x" title="Permalink to this headline">¶</a></h1>
<p>RDFLib version 4.0 introduced a small number of backwards compatible changes that you should know about when porting code from version 3 or earlier.</p>
<div class="section" id="sparql-and-sparqlstore-are-now-included-in-core">
<h2>SPARQL and SPARQLStore are now included in core<a class="headerlink" href="#sparql-and-sparqlstore-are-now-included-in-core" title="Permalink to this headline">¶</a></h2>
<p>For version 4.0 we’ve merged the SPARQL implementation from <tt class="docutils literal"><span class="pre">rdflib-sparql</span></tt>, the SPARQL(Update)Store from <tt class="docutils literal"><span class="pre">rdflib-sparqlstore</span></tt> and miscellaneous utilities from <tt class="docutils literal"><span class="pre">rdfextras</span></tt>. If you used any of these previously, everything you need should now be included.</p>
</div>
<div class="section" id="datatyped-literals">
<h2>Datatyped literals<a class="headerlink" href="#datatyped-literals" title="Permalink to this headline">¶</a></h2>
<p>We separate lexical and value space operations for datatyped literals.</p>
<p>This mainly affects the way datatyped literals are compared. Lexical space comparisons are done by default for <tt class="docutils literal"><span class="pre">==</span></tt> and <tt class="docutils literal"><span class="pre">!=</span></tt>, meaning the exact lexical representation and the exact data-types have to match for literals to be equal. Value space comparisons are also available through the <a class="reference internal" href="apidocs/rdflib.html#rdflib.term.Identifier.eq" title="rdflib.term.Identifier.eq"><tt class="xref py py-meth docutils literal"><span class="pre">rdflib.term.Identifier.eq()</span></tt></a> and <a class="reference internal" href="apidocs/rdflib.html#rdflib.term.Identifier.neq" title="rdflib.term.Identifier.neq"><tt class="xref py py-meth docutils literal"><span class="pre">rdflib.term.Identifier.neq()</span></tt></a> methods, <tt class="docutils literal"><span class="pre"><</span> <span class="pre">></span> <span class="pre"><=</span> <span class="pre">>=</span></tt> are also done in value space.</p>
<p>Most things now work in a fairly sane and sensible way, if you do not have existing stores/intermediate stored sorted lists, or hash-dependent something-or-other, you should be good to go.</p>
<p>Things to watch out for:</p>
<div class="section" id="literals-no-longer-compare-equal-across-data-types-with">
<h3>Literals no longer compare equal across data-types with <tt class="docutils literal"><span class="pre">`==`</span></tt><a class="headerlink" href="#literals-no-longer-compare-equal-across-data-types-with" title="Permalink to this headline">¶</a></h3>
<p>i.e.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">Literal</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span> <span class="n">datatype</span><span class="o">=</span><span class="n">XSD</span><span class="o">.</span><span class="n">int</span><span class="p">)</span> <span class="o">==</span> <span class="n">Literal</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span> <span class="n">datatype</span><span class="o">=</span><span class="n">XSD</span><span class="o">.</span><span class="n">float</span><span class="p">)</span>
<span class="go">False</span>
</pre></div>
</div>
<p>But a new method <a class="reference internal" href="apidocs/rdflib.html#rdflib.term.Identifier.eq" title="rdflib.term.Identifier.eq"><tt class="xref py py-meth docutils literal"><span class="pre">rdflib.term.Identifier.eq()</span></tt></a> on all Nodes has been introduced, which does semantic equality checking, i.e.:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">Literal</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span> <span class="n">datatype</span><span class="o">=</span><span class="n">XSD</span><span class="o">.</span><span class="n">int</span><span class="p">)</span><span class="o">.</span><span class="n">eq</span><span class="p">(</span><span class="n">Literal</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span> <span class="n">datatype</span><span class="o">=</span><span class="n">XSD</span><span class="o">.</span><span class="n">float</span><span class="p">))</span>
<span class="go">True</span>
</pre></div>
</div>
<p>The <tt class="docutils literal"><span class="pre">eq</span></tt> method is still limited to what data-types map to the same <em>value space</em>, i.e. all numeric types map to numbers and will compare, <tt class="docutils literal"><span class="pre">xsd:string</span></tt> and <tt class="docutils literal"><span class="pre">plain</span> <span class="pre">literals</span></tt> both map to strings and compare fine, but:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">Literal</span><span class="p">(</span><span class="mi">2</span><span class="p">,</span> <span class="n">datatype</span><span class="o">=</span><span class="n">XSD</span><span class="o">.</span><span class="n">int</span><span class="p">)</span><span class="o">.</span><span class="n">eq</span><span class="p">(</span><span class="n">Literal</span><span class="p">(</span><span class="s">'2'</span><span class="p">))</span>
<span class="go">False</span>
</pre></div>
</div>
</div>
<div class="section" id="literals-will-be-normalised-according-to-datatype">
<h3>Literals will be normalised according to datatype<a class="headerlink" href="#literals-will-be-normalised-according-to-datatype" title="Permalink to this headline">¶</a></h3>
<p>If you care about the exact lexical representation of a literal, and not just the value. Either set <tt class="xref py py-data docutils literal"><span class="pre">rdflib.NORMALIZE_LITERALS</span></tt> to <tt class="docutils literal"><span class="pre">False</span></tt> before creating your literal, or pass <tt class="docutils literal"><span class="pre">normalize=False</span></tt> to the Literal constructor</p>
</div>
<div class="section" id="ordering-of-literals-and-nodes-has-changed">
<h3>Ordering of literals and nodes has changed<a class="headerlink" href="#ordering-of-literals-and-nodes-has-changed" title="Permalink to this headline">¶</a></h3>
<p>Comparing literals with <tt class="docutils literal"><span class="pre"><,</span> <span class="pre">>,</span> <span class="pre"><=,</span> <span class="pre">>=</span></tt> now work same as in SPARQL filter expressions.</p>
<p>Greater-than/less-than ordering comparisons are also done in value space, when compatible datatypes are used.
Incompatible datatypes are ordered by data-type, or by lang-tag.
For other nodes the ordering is <tt class="docutils literal"><span class="pre">None</span> <span class="pre"><</span> <span class="pre">BNode</span> <span class="pre"><</span> <span class="pre">URIRef</span> <span class="pre"><</span> <span class="pre">Literal</span></tt></p>
<p>Any comparison with non-rdflib Node are <tt class="docutils literal"><span class="pre">NotImplemented</span></tt>
In PY2.X some stable order will be made up by python.
In PY3 this is an error.</p>
</div>
<div class="section" id="custom-mapping-of-datatypes-to-python-objects">
<h3>Custom mapping of datatypes to python objects<a class="headerlink" href="#custom-mapping-of-datatypes-to-python-objects" title="Permalink to this headline">¶</a></h3>
<p>You can add new mappings of datatype URIs to python objects using the <a class="reference internal" href="apidocs/rdflib.html#rdflib.term.bind" title="rdflib.term.bind"><tt class="xref py py-func docutils literal"><span class="pre">rdflib.term.bind()</span></tt></a> method.
This also allows you to specify a constructor for constructing objects from the lexical string representation, and a serialization method for generating a lexical string representation from an object.</p>
</div>
</div>
<div class="section" id="minor-changes">
<h2>Minor Changes<a class="headerlink" href="#minor-changes" title="Permalink to this headline">¶</a></h2>
<ul>
<li><p class="first"><a class="reference internal" href="apidocs/rdflib.html#rdflib.namespace.Namespace" title="rdflib.namespace.Namespace"><tt class="xref py py-class docutils literal"><span class="pre">rdflib.namespace.Namespace</span></tt></a> is no longer a sub-class of <a class="reference internal" href="apidocs/rdflib.html#rdflib.term.URIRef" title="rdflib.term.URIRef"><tt class="xref py py-class docutils literal"><span class="pre">rdflib.term.URIRef</span></tt></a>
this was changed as it makes no sense for a namespace to be a node in a graph, and was causing numerous bug. Unless you do something very special, you should not notice this change.</p>
</li>
<li><p class="first">The identifiers for Graphs are now converted to URIRefs if they are not a <a class="reference internal" href="apidocs/rdflib.html#rdflib.term.Node" title="rdflib.term.Node"><tt class="xref py py-class docutils literal"><span class="pre">rdflib.term.Node</span></tt></a>, i.e. no more graphs with string identifiers. Again, unless you do something quite unusual, you should not notice.</p>
</li>
<li><p class="first">String concatenation with URIRefs now returns URIRefs, not strings:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">URIRef</span><span class="p">(</span><span class="s">"http://example.org/people/"</span><span class="p">)</span> <span class="o">+</span> <span class="s">"Bill"</span>
</pre></div>
</div>
<p>rdflib.term.URIRef(u’<a class="reference external" href="http://example.org/people/Bill">http://example.org/people/Bill</a>‘)</p>
<p>This is be convenient, but may cause trouble if you expected a string.</p>
</li>
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<h3><a href="index.html">Table Of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">Upgrading from RDFLib version 3.X to 4.X</a><ul>
<li><a class="reference internal" href="#sparql-and-sparqlstore-are-now-included-in-core">SPARQL and SPARQLStore are now included in core</a></li>
<li><a class="reference internal" href="#datatyped-literals">Datatyped literals</a><ul>
<li><a class="reference internal" href="#literals-no-longer-compare-equal-across-data-types-with">Literals no longer compare equal across data-types with <tt class="docutils literal"><span class="pre">`==`</span></tt></a></li>
<li><a class="reference internal" href="#literals-will-be-normalised-according-to-datatype">Literals will be normalised according to datatype</a></li>
<li><a class="reference internal" href="#ordering-of-literals-and-nodes-has-changed">Ordering of literals and nodes has changed</a></li>
<li><a class="reference internal" href="#custom-mapping-of-datatypes-to-python-objects">Custom mapping of datatypes to python objects</a></li>
</ul>
</li>
<li><a class="reference internal" href="#minor-changes">Minor Changes</a></li>
</ul>
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