How can I create an empty array node using json's property_tree boost parser

advertisements

I'm trying to create an array node in json, which output is like this:

{
    node: ["12", "13"]
}

but when array is empty, it will output this:

{
    node: ""
}

that's not what I want, I need this:

{
    node: []
}

How can I do that ? And I don't need double quotes("") around numbers. Can anyone help ?

My code is like below:

boost::property_tree::ptree pt;
boost::property_tree::ptree array;
for (vector<int>::const_iterator iter = v.begin();
    iter != v.end();
    ++iter)
{
    boost::property_tree::ptree node;
    node.put("code", *iter);
    array.push_back(std::make_pair("", node));
}
pt.add_child("array", array);

Thanks for your attention.


Boost doesn't have a JSON library. It has a property-tree (think: hierarchical configuration formats) library.

documentation: http://www.boost.org/doc/libs/1_58_0/doc/html/property_tree/parsers.html#property_tree.parsers.json_parser

It specifically states that some things are not well-supported:

  • arrays in JSON are a hack (you cannot represent the empty array)
  • all type information is lost (everything needs to be JSON string)

This suits the intended application domains for Boost PropertyTree. If it doesn't suit your problem, use a JSON library.