D3 JSON Creation - The How

2023-02-18

Superseded on 2023-04-17.

To create json in D3, I have 3 functions. JSON.ADD, JSON.CREATE.OBJECT and JSON.CREATE.ARRAY.

JSON.ADD creates a key value pair. In D3, this will simply add an attribute to a dynamic array containing our key and value.

    SUBROUTINE JSON.ADD(BUFFER,KEY,VALUE)
*
    IF BUFFER = '' THEN
        BUFFER = KEY : @VM : VALUE
    END ELSE
        BUFFER = BUFFER : @AM : KEY : @VM : VALUE
    END
*
    RETURN
*
* END OF PROGRAM
*
    END
*

The next function is the JSON.CREATE.OBJECT function. This has a tiny bit of logic to handle things.

    SUBROUTINE JSON.CREATE.OBJECT(JSON,BUFFER)
*
    NUMBER.OF.KEYS = DCOUNT(BUFFER,@AM)
    JSON = ''
*
    FOR I = 1 TO NUMBER.OF.KEYS
        KEY = TRIM(BUFFER<I,1>)
        VALUE = TRIM(BUFFER<I,2>)
*
        IF VALUE # '' AND (VALUE[1,1] = '[' OR VALUE[1,1] = '{' OR NUM(VALUE)) THEN
            JSON<-1> = '"' : KEY : '": ' : VALUE
*
        END ELSE
            KEY = CHANGE(KEY,'"','\"')
            VALUE = CHANGE(VALUE,'"','\"')
*
            JSON<-1> = '"' : KEY : '": "' : VALUE : '"'
        END
    NEXT I
*
    CONVERT @AM TO ',' IN JSON
    JSON = '{ ' : JSON : ' }'
*
    RETURN
*
* END OF PROGRAM
*
    END
*

Here I check if the value is blank, if it is blank, then it will give an empty string. If the value starts with a '[' or a '{', then I'm assuming the string has already been converted to a json array or a json object.

Special Note You cannot use square or curly brackets as a starting character for a json value.

The last function is the JSON.CREATE.ARRAY function:

    SUBROUTINE JSON.CREATE.ARRAY(JSON.ARRAY,BUFFER)
*
    CONVERT @AM TO ',' IN BUFFER
    JSON.ARRAY = '[' : BUFFER : ']'
*
    RETURN
*

With that we have a set of functions that can generate json easily.