https://svn.boost.org/trac10/ticket/9496 <p> When using boost::property_tree::write_json it will write all types as strings, which is unwanted when wanting to preserve the correct types for data. </p> <ul><li>The boolean value is stored as the string "true" or "false", </li><li>Null is stored as the string "null" </li><li>Numeric values are also stored as strings </li><li>Floating point values might end up in their scientific, lossy representations </li></ul><p> For my purposes, I need to transfer numeric values (unix timestamps represented as double) in their most accurate representation using JSON and boolean values to represent correct boolean values without writing another text-to-bool converter. </p> <p> I will attach a patch that fixes this. For every value in the property_tree, it will </p> <ul><li>try to match is with boolean true or false, and write that value unquoted to the JSON output </li><li>try to read it as an integer and if that succeeds, write it unquoted to the JSON output </li><li>try to read it as a double value and if that succeeds, write it unquoted with appropriate numeric precision (based on std::numeric_limits) to the JSON output </li><li>try to see if the string matches 'null' and if it does, it will write null unquoted to the JSON output </li><li>if all else fails, write the value as a quoted string to the JSON output </li></ul><p> This will make it a lot easier to interpret the JSON on the receiving and, and greatly improve accuracy for double values. </p> en-us /htdocs/site/boost.png https://svn.boost.org/trac10/ticket/9496 Trac 1.4.3 Egbert van der Wal <ewal@…> Sun, 15 Dec 2013 12:10:55 GMT https://svn.boost.org/trac10/ticket/9496 https://svn.boost.org/trac10/ticket/9496 <ul> <li><strong>attachment</strong> → <span class="trac-field-new">boost_property_tree_json.patch</span> </li> </ul> <p> Patch on SVN Trunk to improve the JSON output of the boost::property_tree::write_json function </p> Ticket anonymous Mon, 10 Feb 2014 13:28:34 GMT https://svn.boost.org/trac10/ticket/9496#comment:2 https://svn.boost.org/trac10/ticket/9496#comment:2 <ul> <li><strong>status</strong> <span class="trac-field-old">new</span> → <span class="trac-field-new">closed</span> </li> <li><strong>resolution</strong> → <span class="trac-field-new">invalid</span> </li> </ul> <p> I'm not going to include this. </p> <p> With or without this patch the behavior is not right: without it, everything becomes a string when reading, and is written as such. With it, everything still turns into a string on reading, but now some strings suddenly become not-strings when writing. </p> <p> In other words, this makes the writer harder to understand, and possibly incorrect - what if I actually want to write "2.0" to the JSON file? Maybe the JSON represents a music collection which contains the album by Garbage of that name. </p> <p> I do hope to eventually support a ptree that uses a variant value type to accurately represent JSON, but until then I will stick with pure strings as the simple and obvious thing. If that is insufficient for your needs, I'm afraid you'll have to use a real JSON library. </p> Ticket Egbert van der Wal <ewal@…> Mon, 10 Feb 2014 15:12:11 GMT