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From: <ian...@us...> - 2003-09-07 19:15:51
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Update of /cvsroot/sqlobject/SOWeb/docs In directory sc8-pr-cvs1:/tmp/cvs-serv1774/docs Modified Files: FAQ.html FAQ.txt default.css Log Message: Updated docs Index: FAQ.html =================================================================== RCS file: /cvsroot/sqlobject/SOWeb/docs/FAQ.html,v retrieving revision 1.2 retrieving revision 1.3 diff -C2 -d -r1.2 -r1.3 *** FAQ.html 7 Sep 2003 18:21:38 -0000 1.2 --- FAQ.html 7 Sep 2003 19:15:46 -0000 1.3 *************** *** 22,25 **** --- 22,26 ---- <li><a class="reference" href="#composite-compound-attributes" id="id5" name="id5">Composite/Compound Attributes</a></li> <li><a class="reference" href="#non-integer-ids" id="id6" name="id6">Non-Integer IDs</a></li> + <li><a class="reference" href="#binary-values" id="id7" name="id7">Binary Values</a></li> </ul> </div> *************** *** 276,279 **** --- 277,316 ---- cannot use strings or other kinds of values.</p> <p>This restriction will probably be removed soon.</p> + </div> + <div class="section" id="binary-values"> + <h1><a name="binary-values">Binary Values</a></h1> + <p>Binary values can be difficult to store in databases, as SQL doesn't + have a widely-implemented way to express binaries as literals, and + there's differing support in database.</p> + <p>A possible way to keep this data in a database is by using encoding. + Base 64 is a good encoding, reasonably compact but also safe. As + an example, imagine you want to store images in the database:</p> + + <pre class="literal-block"><tt><span class="keyword">class</span> <span class="function">Image</span><span class="symbol">(</span><span class="normal">SQLObject</span><span class="symbol">)</span><span class="symbol">:</span> + + <span class="normal">data</span> <span class="symbol">=</span> <span class="function">StringCol</span><span class="symbol">(</span><span class="symbol">)</span> + <span class="normal">height</span> <span class="symbol">=</span> <span class="function">IntCol</span><span class="symbol">(</span><span class="symbol">)</span> + <span class="normal">width</span> <span class="symbol">=</span> <span class="function">IntCol</span><span class="symbol">(</span><span class="symbol">)</span> + + <span class="keyword">def</span> <span class="function">_set_data</span><span class="symbol">(</span><span class="normal">self</span><span class="symbol">,</span> <span class="normal">value</span><span class="symbol">)</span><span class="symbol">:</span> + <span class="normal">self</span><span class="symbol">.</span><span class="function">_SO_set_data</span><span class="symbol">(</span><span class="normal">value</span><span class="symbol">.</span><span class="function">encode</span><span class="symbol">(</span><span class="string">'base64'</span><span class="symbol">)</span><span class="symbol">)</span> + + <span class="keyword">def</span> <span class="function">_get_data</span><span class="symbol">(</span><span class="normal">self</span><span class="symbol">,</span> <span class="normal">value</span><span class="symbol">)</span><span class="symbol">:</span> + <span class="keyword">return</span> <span class="normal">self</span><span class="symbol">.</span><span class="function">_SO_get_data</span><span class="symbol">(</span><span class="symbol">)</span><span class="symbol">.</span><span class="function">decode</span><span class="symbol">(</span><span class="string">'base64'</span><span class="symbol">)</span> + </tt></pre> + <p>SQLite does not respect backslash quoting, so for instance <tt class="literal"><span class="pre">\n</span></tt> is + not interpreted as a newline. For the moment there's no resolution, + and this will mess up your base64-encoded values. As a workaround:</p> + + <pre class="literal-block"><tt><span class="keyword">class</span> <span class="function">Image</span><span class="symbol">(</span><span class="normal">SQLObject</span><span class="symbol">)</span><span class="symbol">:</span> + <span class="normal">data</span> <span class="symbol">=</span> <span class="function">StringCol</span><span class="symbol">(</span><span class="symbol">)</span> + + <span class="keyword">def</span> <span class="function">_set_data</span><span class="symbol">(</span><span class="normal">self</span><span class="symbol">,</span> <span class="normal">value</span><span class="symbol">)</span><span class="symbol">:</span> + <span class="comment"># base64 just ignores whitespace, so we can get rid of \n's</span> + <span class="normal">self</span><span class="symbol">.</span><span class="function">_SO_set_data</span><span class="symbol">(</span><span class="normal">value</span><span class="symbol">.</span><span class="function">encode</span><span class="symbol">(</span><span class="string">'base64'</span><span class="symbol">)</span><span class="symbol">.</span><span class="function">replace</span><span class="symbol">(</span><span class="string">'\n'</span><span class="symbol">,</span> <span class="string">''</span><span class="symbol">)</span><span class="symbol">)</span> + + <span class="keyword">def</span> <span class="function">_get_data</span><span class="symbol">(</span><span class="normal">self</span><span class="symbol">)</span><span class="symbol">:</span> + <span class="keyword">return</span> <span class="normal">self</span><span class="symbol">.</span><span class="function">_SO_get_data</span><span class="symbol">(</span><span class="symbol">)</span><span class="symbol">.</span><span class="function">decode</span><span class="symbol">(</span><span class="string">'base64'</span><span class="symbol">)</span> + </tt></pre> </div> </div> Index: FAQ.txt =================================================================== RCS file: /cvsroot/sqlobject/SOWeb/docs/FAQ.txt,v retrieving revision 1.2 retrieving revision 1.3 diff -C2 -d -r1.2 -r1.3 *** FAQ.txt 7 Sep 2003 18:21:38 -0000 1.2 --- FAQ.txt 7 Sep 2003 19:15:46 -0000 1.3 *************** *** 154,155 **** --- 154,177 ---- This restriction will probably be removed soon. + + Binary Values + ------------- + + Binary values can be difficult to store in databases, as SQL doesn't + have a widely-implemented way to express binaries as literals, and + there's differing support in database. + + A possible way to keep this data in a database is by using encoding. + Base 64 is a good encoding, reasonably compact but also safe. As + an example, imagine you want to store images in the database: + + .. raw:: html + :file: ../examples/snippets/image-binary.html + + SQLite does not respect backslash quoting, so for instance ``\n`` is + not interpreted as a newline. For the moment there's no resolution, + and this will mess up your base64-encoded values. As a workaround: + + .. raw:: html + :file: ../examples/snippets/image-binary-sqlite.html + Index: default.css =================================================================== RCS file: /cvsroot/sqlobject/SOWeb/docs/default.css,v retrieving revision 1.8 retrieving revision 1.9 diff -C2 -d -r1.8 -r1.9 |
