为什么Boost属性树write_json会将所有内容保存为字符串?有可能改变吗? [英] Why does Boost property tree write_json save everything as string? Is it possible to change that?

问题描述

我正在尝试使用boost属性树write_json进行序列化，它将所有内容保存为字符串，这并不是数据错误，但是我每次都需要显式转换它们，并且想在其他地方使用它们. (例如在python或其他C ++ json(非增强型)库中)

I'm trying to serialize using boost property tree write_json, it saves everything as strings, it's not that data are wrong, but I need to cast them explicitly every time and I want to use them somewhere else. (like in python or other C++ json (non boost) library)

这是一些示例代码，我所得到的取决于语言环境:

here is some sample code and what I get depending on locale:

boost::property_tree::ptree root, arr, elem1, elem2;
elem1.put<int>("key0", 0);
elem1.put<bool>("key1", true);
elem2.put<float>("key2", 2.2f);
elem2.put<double>("key3", 3.3);
arr.push_back( std::make_pair("", elem1) );
arr.push_back( std::make_pair("", elem2) );
root.put_child("path1.path2", arr);

std::stringstream ss;
write_json(ss, root);
std::string my_string_to_send_somewhare_else = ss.str();

和my_string_to_send_somewhere_else是sth.像这样:

{
    "path1" :
    {
       "path2" :
       [
            {
                 "key0" : "0",
                 "key1" : "true"
            },
            {
                 "key2" : "2.2",
                 "key3" : "3.3"
            }
       ]
    }
}

是否仍然可以将它们另存为值，例如: "key1" : true或"key2" : 2.2?

Is there anyway to save them as the values, like: "key1" : true or "key2" : 2.2?

推荐答案

我能想到的最简单，最干净的解决方案是使用占位符生成JSON，最后用实际值替换掉多余的引号.

The simplest and cleanest solution that i could come up with was generating the JSON with placeholders and in the end string replacing with the actual value ditching the extra quotes.

static string buildGetOrdersCommand() {
    ptree root;
    ptree element;
    element.put<string>("pendingOnly", ":pendingOnly");
    element.put<string>("someIntValue", ":someIntValue");

    root.put("command", "getOrders");
    root.put_child("arguments", element);

    std::ostringstream buf;
    write_json(buf, root, false);
    buf << std::endl;

    string json = buf.str();
    replace(json, ":pendingOnly", "true");
    replace(json, ":someIntValue", std::to_string(15));

    return json;
}

static void replace(string& json, const string& placeholder, const string& value) {
    boost::replace_all<string>(json, "\"" + placeholder + "\"", value);
}

结果是

{"command":"getOrders"，"arguments":{"pendingOnly":true，"someIntValue":15}}

{"command":"getOrders","arguments":{"pendingOnly":true,"someIntValue":15}}

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