Libraries: JSON Serialization and Deserialization (native MQL)

[Automated-Trading]

JSON Serialization and Deserialization (native MQL):

Serialization and deserialization of JSON protocol. The code is ported from a high-speed С++ library.

Practical example: authorization on a website and parsing the response

CJAVal jv;
jv["login"]="Login"; // login
jv["password"]="Pass"; // password

//--- serialize to string  {"login":"Login","password":"Pass"}
char data[]; 
ArrayResize(data, StringToCharArray(jv.Serialize(), data, 0, WHOLE_ARRAY)-1);

//--- send data
char res_data[];
string res_headers=NULL;
int r=WebRequest("POST", "http://my.site.com/Authorize", "Content-Type: text/plain\r\n", 5000, data, res_data, res_headers);

//--- assume the answer {"accessToken":"ABRAKADABRA","session_id":124521}
//--- get AccessToken
jv.Deserialize(res_data);
string AccessToken=jv["accessToken"].ToStr();

Author: o_O

[Amy Liu]

After update MetaEditor to Version: 5.00 build 1498, compiling the code generates error bellow:

cannot implicitly convert type 'string' to 'bool'.

Line 53: void operator=(string a) { m_type=a?jtSTR:jtNULL; m_sv=a; m_iv=StringToInteger(m_sv); m_dv=StringToDouble(m_sv); m_bv=a!=NULL; }

It seems that  m_type=a?jtSTR:jtNULL is not supported in this version.

[Resophonic]

The author has published an update which addresses this issue.

[Amy Liu]

Amy Liu:

After update MetaEditor to Version: 5.00 build 1498, compiling the code generates error bellow:

cannot implicitly convert type 'string' to 'bool'.

Line 53: void operator=(string a) { m_type=a?jtSTR:jtNULL; m_sv=a; m_iv=StringToInteger(m_sv); m_dv=StringToDouble(m_sv); m_bv=a!=NULL; }

It seems that  m_type=a?jtSTR:jtNULL is not supported in this version.

Fixes:

Line  53: void operator=(string a) { m_type=a!=NULL?jtSTR:jtNULL; m_sv=a; m_iv=StringToInteger(m_sv); m_dv=StringToDouble(m_sv); m_bv=a!=NULL; }

Line 80: case jtSTR: m_sv=Unescape(a); m_type=m_sv!=NULL?jtSTR:jtNULL; m_iv=StringToInteger(m_sv); m_dv=StringToDouble(m_sv); m_bv=m_sv!=NULL; break;

[Amy Liu]

Resophonic:
The author has published an update which addresses this issue.

I have fixed this issue. But it will be good to see what the author did. How can I find it? Thanks.

[Resophonic]

Amy Liu:
I have fixed this issue. But it will be good to see what the author did. How can I find it? Thanks.

You can download it here: https://www.mql5.com/en/code/13663

[Amy Liu]

Resophonic:
You can download it here: https://www.mql5.com/en/code/13663

Thank you very much!

[spalle]

Hi there, firstly thanks for this very powerful tool - is there by any chance some documentation available anywhere? or some more examples of usage? Warm regards

[[Deleted]]

Hi there, thanks for this native MQL and fast library, it will be more helpful if there is a documentation, special when working with JSON arrays and objects, how to extract data from them:
Suppose:

[[0.88678,true],[0.88668,false]]
How can I map this to MQL types after Deserialize?

[[Deleted]]

Would anyone or the author answer if this is supposed to support nested JSON? That is a CJAVal instance contains a keys '2', and '3' which are another CJAVal instance. Code seems to run but when serialized the keys are blank.

Example, I am getting:

{"":{"sl":5270.98000000,"tp":5285.26000000,"order":2},"":{"sl":5274.80000000,"tp":5289.06000000,"order":3}}

But should be getting 

{"2":{"sl":5270.98000000,"tp":5285.26000000,"order":2},"3":{"sl":5274.80000000,"tp":5289.06000000,"order":3}}

[Taras Slobodyanik]

danielsokolowsk:

Would anyone or the author answer if this is supposed to support nested JSON? That is a CJAVal instance contains a keys '2', and '3' which are another CJAVal instance. Code seems to run but when serialized the keys are blank.

Example, I am getting:

But should be getting 

https://www.mql5.com/ru/forum/63015

a few examples

   string a[] = {"1", "2", "3"};
   int b[] = {1, 2, 3};
   
   CJAVal js;
   js["a"].Add(a[0]);
   js["a"].Add(a[1]);
   js["a"].Add(a[2]);
        
   js["b"].Add(b[0]);
   js["b"].Add(b[1]);
   js["b"].Add(b[2]);
   
   js["c"][0]=1.1;
   js["c"][1]=2.9;
   js["c"][2]=3.03;
   
   string t=js.Serialize();
   Print(t);   // {"a":["1","2","3"],"b":[1,2,3],"c":[1.10000000,2.90000000,3.03000000]}   
   
   
   js.Clear();
   js.Deserialize(t); 
   Print(js["c"][2].ToStr()); //  3.03000000

array of arrays

JAval j1; j1.Add(1);

JAval j2; j2.Add(2); j2.Add(3);

JAval js;

js["a"].Add(j1);
js["a"].Add(j2);

// { a: [ [1], [2,3] ]; }