Bug: JSON Parsing Failure for the quoted string

[karuna2git]

Problem/Opportunity

WPEFramework::Core::JSON::String::Deserialize() is skipping the parsing of the string is having a quoted string.

The change landed under #1625 is causing this issue.

Steps to reproduce

Compile n run the program

    int main()
    {
        std::string textIn  =  R"json({"payload":"This is test\" message"})json";
        std::string textOut = "";
        Core::JSON::String json;

        // Text Conversion
        json.FromString(textIn);
        json.ToString(textOut);

        // Print the strings
        printf ("textIn  :: %s\n", textIn.c_str());
        printf ("textOut :: %s\n", textOut.c_str());

         return 0;
    }

Expected Behavior

textIn  :: {"payload":"This is test\" message"}
textOut :: "{\"payload\":\"This is test\\\" message\"}"

Actual Behavior

textIn  :: {"payload":"This is test\" message"}
textOut :: ""

Notes (Optional)

No response

[woutermeek]

@karuna2git have you tested with this commit: 11b9299

This is the parser from 5.x which solves a lot of problems.

[karuna2git]

Hi @woutermeek , Im reporting this issue in 5.2.0 release.
And yes, it is happening in the 4.4.4 release as well as the latest commit you advised 11b9299.

[MFransen69]

Hi @karuna2git

This is not a bug but expected behaviour.

As well as the json.ToString(textOut); outputs a quoted json string and not a C++ string (as you correctly show in the expected result printed for this line) the same goes for FromString, it expects always a quoted json string as input and not a C++ string.

So you should provide the string as quoted like this when you use FromString:

                // version 1: provide a quoted string ourselfes
                std::string textIn = R"json("{\"payload\":\"This is test \\\" message\"}")json";
                std::string textOut = "";
                Core::JSON::String json;

                // Text Conversion
                json.FromString(textIn);
                json.ToString(textOut);

                // Print the strings
                printf("textIn  :: %s\n", textIn.c_str());
                printf("textOut :: %s\n", textOut.c_str());

Of course there is a much easier way to do this and not use FromString (FromString is meant to be used if you actually did get a quoted string in your hands and not for C++ strings) but the operator=(const string& RHS) which expects the string to be C++ of course and not quoted (note do not use the constructor as that sets the default value not the set value):

                // version 2 (easiest :) ): assign the c++ string (so not the quoted string)
                std::string textIn = R"json({"payload":"This is test \" message"})json";
                std::string textOut = "";
                Core::JSON::String json;

                // Text Conversion
                json = textIn;
                json.ToString(textOut);

                // Print the strings
                printf("textIn  :: %s\n", textIn.c_str());
                printf("textOut :: %s\n", textOut.c_str());

And just to show there is also a Core function to "quote" a C++ string in code might you ever need it (note now the \ must still be quoted ourselfes as ToQuotedString only does it for quotes or whatever you provide as first param):

`
       // version 3 (just to show how to create quoted string in code)
       std::string textIn = R"json({"payload":"This is test \\" message"})json";
       std::string textOut = "";
       Core::JSON::String json;

       // Text Conversion
       json.FromString(Core::ToQuotedString('\"', textIn));
       json.ToString(textOut);

       // Print the strings
       printf("textIn  :: %s\n", textIn.c_str());
       printf("textOut :: %s\n", textOut.c_str());
`

Note in case you want the C++ string as output and not the quoted string something similar applies, do not use the ToString (always quoted) but Value(). If the Value() output is quoted or not is depended on the quoted setting for the JSON String (and good you brought this topic up, while testing the above I noticed the quoted setting is not taken into account properly I think when outputing Value(), I created a Jira ticket for this).

[MFransen69]

Hi @karuna2git
After looking into the above some more I think my statement above was too bold. We seem to allow opaque (non json strings) as input (and output again in ToString) and as you mentioned the usage of " inside a opaque string did work in the past so is probably valid in an opaque string and it is a valid bug (the whole opaque/quoted=false handling already caused more confusion in the past).
At the moment the usage of opaque strings in JSON String seems confusing (including the usage of the quoted flag) and unclear/confusing/partly broken.
So we will pick this up as a general improvement of JSON String opaque handling and also look at the interface for JSON String for this usage.
In the mean time the above examples are still correct of course, and when in doubt feed a json string into FromString instead of a opaque/C++ string or feed the c++ string using the assignment operator.