Tcl

Get the Root of a JSON Document

See more JSON Examples

Demonstrates how to get back to the JSON root object from anywhere in the JSON document. This example uses the following JSON document:

{
  "flower": "tulip",
  "abc":
    {
    "x": [
       { "a" : 1 },
       { "b1" : 100, "b2" : 200 },
       { "c" : 3 }
    ],
    "y": 200,
    "z": 200
    }
}

Tcl

load ./chilkat.dll

set success 0

set json [new_CkJsonObject]

set jsonStr "{\"flower\": \"tulip\",\"abc\":{\"x\": [{ \"a\" : 1 },{ \"b1\" : 100, \"b2\" : 200 },{ \"c\" : 3 }],\"y\": 200,\"z\": 200}}"

set success [CkJsonObject_Load $json $jsonStr]
if {$success == 0} then {
    puts [CkJsonObject_lastErrorText $json]
    delete_CkJsonObject $json
    exit
}

# Get the "abc" object.
set abcObj [new_CkJsonObject]

set success [CkJsonObject_ObjectOf2 $json "abc" $abcObj]
if {$success == 0} then {
    puts [CkJsonObject_lastErrorText $json]
    delete_CkJsonObject $json
    delete_CkJsonObject $abcObj
    exit
}

# Side note: The JSON of a sub-part of the document can be emitted from any JSON object:
CkJsonObject_put_EmitCompact $abcObj 0
puts [CkJsonObject_emit $abcObj]

# Navigate to the "x" array
set xArray [new_CkJsonArray]

CkJsonObject_ArrayOf2 $abcObj "x" $xArray

# Navigate to the 2nd object contained within the array.  This contains members b1 and b2
set bObj [new_CkJsonObject]

CkJsonArray_ObjectAt2 $xArray 1 $bObj

# Show that we're at "b1/b2".
# The value of "b1" should be "200"
puts "b2 = [CkJsonObject_IntOf $bObj b2]"

# Now go back to the JSON doc root:
set docRoot [new_CkJsonObject]

CkJsonObject_GetDocRoot2 $bObj $docRoot

# We'll skip the null check and assume it's non-null...

# Pretty-print the JSON doc from the root to show that this is indeed the root.
CkJsonObject_put_EmitCompact $docRoot 0
puts [CkJsonObject_emit $docRoot]

delete_CkJsonObject $json
delete_CkJsonObject $abcObj
delete_CkJsonArray $xArray
delete_CkJsonObject $bObj
delete_CkJsonObject $docRoot