Visual FoxPro

Check if Integer Exists at JSON Path

Demonstrates how to get an integer value at a JSON path, and how to check to see if it exists. Visual FoxPro

LOCAL lnSuccess
LOCAL loJson
LOCAL lcPath
LOCAL lnVal
LOCAL lnWasFound

lnSuccess = 0

loJson = CreateObject('Chilkat.JsonObject')

* First build simple JSON..
loJson.UpdateInt("test.abc",100)

loJson.EmitCompact = 0
? loJson.Emit()

* This is our JSON:
* {
*   "test": {
*     "abc": 100,
*   }
* }

lcPath = "test.notHere"

* The call to IntOf will return 0, because it's not present.
* But how do we know if it really was present, and the value was truly 0?
lnVal = loJson.IntOf(lcPath)
? "val = " + STR(lnVal)

* We cannot use LastMethodSuccess because LastMethodSuccess only applies
* to methods that:
* - return a string
* - return a new Chilkat object, binary bytes, or a date/time.
* - returns a boolean status where 1 = success and 0 = failed.
* - returns an integer where failure is defined by a return value less than zero.
* The IntOf method fits none of these requirements, and therefore the LastMethodSuccess 
* is not a valid indicator..
lnWasFound = loJson.LastMethodSuccess
? "wasFound = " + STR(lnWasFound) + " (not a valid indicator)"

* Instead, if the returned value is 0, we can double-check to see if the member was truly there..
IF (lnVal = 0) THEN
    lnWasFound = loJson.HasMember(lcPath)
    ? "wasFound = " + STR(lnWasFound)
    IF (lnWasFound = 1) THEN
        ? "The value was present and is 0."
    ELSE
        ? "no member is present at test.notHere"
    ENDIF

ELSE
    ? "val = " + STR(lnVal)
ENDIF

* Alternatively, you could check to see if the member exists beforehand..
IF (loJson.HasMember(lcPath) = 1) THEN
    ? "val = " + STR(loJson.IntOf(lcPath))
ELSE
    ? "no member at " + lcPath
ENDIF

RELEASE loJson