Convert strings to numbers

[oysteinmyrmo]

I am using the json library to parse a text file containing json data to insert into an SQLite database. Parsing the file works fine, but everything is stored as strings because the data originates from a Wordpress database on a Wordpress server which gives all the contents as strings because PHP. I can of course read all data as strings and then convert the data to numbers myself (data types are known), but I just wanted to check if there is some built-in functionality for this in the library.

As an example, consider the following json file fetched from the Wordpress server:

{
    "my_table": [
        {
            "id": "1",
            "name": "foo"
        },
        {
            "id": "2",
            "name": "bar"
        }
    ]
}

In C++ I would like to parse like this:

std::string fileContents = getFileContents(); // We get the data somehow
json dbData = json::parse(fileContents);

json tableData = dbData["my_table"];
for (json j : tableData)
{
    // This will fail because PHP gives quoted numbers and j["id"] is thus a string.
    // Can the library do this conversion in some way, or must it be done manually?
    int id = j["id"];

    // This works fine, but it causes some overhead (not really important though).
    // Besides, it is not pretty and kinda bloated. It will also have to handle possible
    // null values in some way.
    std::string sId = j["id"];
    int nId = std::stoi(sId);

    // This is fine, of course.
    std::string name = j["name"];

    // Run some SQLite queries with the data.
}

It is of course also possible to fix this on the server side, but as far as I have been able to figure out it is rather painful and I would like to stay clear of PHP if possible.

[nlohmann]

Hey @oysteinmyrmo, I understand your problem. But this is out of scope of the library: we parse JSON and choose the best C++ type to store the input. If your numbers are given as string, there is nothing we can do about it. If we would add string-to-number conversion to the library, it would consist of the same std::stoi call you described - including any exceptions thrown in case of unsuccessful conversion.

[maddanio]

Actually i disagree a bit. It would be possible to tell the library to allow "lax" parsing where a get<number_type> would automatically do a lexical cast