jsonGetType (Function)

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Architecture:

NX32L

Device support:

All

Firmware version:

2.10.00

jsonGetType returns the type of the provided JSON value.

This can be used to determine which function to call when handling unknown values.

jsonGetType can be used to get the type of the elements in a JSON array by changing the idx value.

 

Input:

o : SYSHANDLE

A handle to a JSON structure.

 

idx : INT (Default -1)

If idx is -1, the type of o will be returned.

If idx is not -1 and o is a JSON array, the type of o[idx] will be returned.

 

Returns: INT

7

- Null.

6

- Boolean. Can be read using jsonSetValueBool.

5

- Floating point number.

4

- Integer.

3

- String.

2

- JSON Array.

1

- JSON Object.

0

- Function is not supported.

-2

- JSON value not found.

-3

- Array element is not found, idx is outside the valid range

-4

- idx is not -1 and o is not an array

 

 

Declaration:

FUNCTION jsonGetType : INT;
VAR_INPUT
  o     : SYSHANDLE;
  idx   : INT := -1;
END_VAR;

 

 

Example:

// Dumps JSON structure to device output
FUNCTION INTERFACE dumpJSON;
VAR_INPUT
  json   : SYSHANDLE;
  prefix : STRING;
END_VAR;
END_FUNCTION;
 
// Dumps array to device output
FUNCTION dumpArray;
VAR_INPUT
  json   : SYSHANDLE;
  prefix : STRING;
END_VAR;
VAR
  type, i, rc : INT;
 
  tmp    : SYSHANDLE;
  key    : STRING;
  txt    : STRING;
  str    : STRING;
  d      : DINT;
  b      : BOOL;
  f      : DOUBLE;
END_VAR;
 
  FOR i := 0 TO jsonArraySize(o:=json) - 1 DO
    txt := strFormat(format:=prefix + "[\1]:", v1:=i);
     
    type := jsonGetType(o:=json, idx:= i);      
    CASE type OF
        1,2:// Object or array
          DebugFmt(message:=txt);
          rc := jsonGetValue(o:=json, idx:=i, value := tmp);
          dumpJSON(json:=tmp, prefix := prefix);
          rc := jsonFree(o:=tmp);
        3: // string
          jsonGetString(o:=json, idx := i, value :=str);
          DebugFmt(message:=txt+":$""+str+"$"");
        4: // int
          jsonGetInt(o:=json, idx := i, value :=d);
          DebugFmt(message:=txt+":\4", v4:=d);
        5: // float
          jsonGetFloat(o:=json, idx := i, value :=f);
          DebugFmt(message:=txt+": "+doubleToStr(v:=f));
        6: // Bool
          jsonGetBool(o:=json, idx := i, value :=b);
          IF b THEN
              DebugFmt(message:=txt+": TRUE");
          ELSE
              DebugFmt(message:=txt+": FALSE");
          END_IF;
        7: //NULL
          DebugFmt(message:=txt+": NULL");
    END_CASE;
  END_FOR;
END_FUNCTION;
 
// Dumps object to device output
FUNCTION dumpObject;
VAR_INPUT
  json   : SYSHANDLE;
  prefix : STRING;
END_VAR;
VAR
  type, i, rc : INT;
 
  tmp    : SYSHANDLE;
  key    : STRING;
  txt    : STRING;
  str    : STRING;
  d      : DINT;
  b      : BOOL;
  f      : DOUBLE;
END_VAR;
 
  i := 0;
  REPEAT
    rc := jsonGetKey(o:=json, idx:= i, key:=key, type:=type);
    txt := prefix + "$""+key+"$"";
    IF rc = 1 THEN            
        CASE type OF
        1,2:// Object or array
          DebugFmt(message:=txt);
          rc := jsonGetValue(o:=json, key:=key, value := tmp);
          dumpJSON(json:=tmp, prefix := prefix);
          rc := jsonFree(o:=tmp);
           
        3: // string
          jsonGetString(o:=json, key:=key, value :=str);
          DebugFmt(message:=txt+":$""+str+"$"");
        4: // int
          jsonGetInt(o:=json, key:=key, value :=d);
          DebugFmt(message:=txt+":\4", v4:=d);          
        5: //Real
          jsonGetFloat(o:=json, key:=key, value :=f);
          DebugFmt(message:=txt+": "+doubleToStr(v:=f));  
        6: // Bool
          jsonGetBool(o:=json, key:=key, value :=b);
          IF b THEN
              DebugFmt(message:=txt+": TRUE");
          ELSE
              DebugFmt(message:=txt+": FALSE");
          END_IF;
        7: // NULL
          DebugFmt(message:=txt+": NULL");  
        END_CASE;
    END_IF;
    i := i+1;
  UNTIL rc < 0
  END_REPEAT;
END_FUNCTION;
 
// Implementation of dumpJSON
FUNCTION IMPLEMENTATION dumpJSON;
VAR
  type: INT;
END_VAR;
 
  type := jsonGetType(o:=json, idx:=-1);
  IF type = 1 THEN // Object
    DebugFmt(message:=prefix+"object{");
    dumpObject(json:=json, prefix:=prefix+" ");  
    DebugFmt(message:=prefix+"}");
  END_IF;
 
  IF type = 2 THEN // Array
    DebugFmt(message:=prefix+"array[");
    dumpArray(json:=json, prefix:=prefix+" ");
    DebugFmt(message:=prefix+"]");
  END_IF;
     
END_FUNCTION;