Tcl

Get the Index of a JSON Member

See more JSON Examples

This example demonstrates how to get the index of a given member by name.

{
  "name": "donut",
  "image":
    {
    "fname": "donut.jpg",
    "w": 200,
    "h": 200
    },
  "thumbnail":
    {
    "fname": "donutThumb.jpg",
    "w": 32,
    "h": 32
    }
}

Tcl

load ./chilkat.dll

set success 0

set json [new_CkJsonObject]

# This is the above JSON with whitespace chars removed (SPACE, TAB, CR, and LF chars).
# The presence of whitespace chars for pretty-printing makes no difference to the Load
# method. 
set jsonStr "{\"name\": \"donut\",\"image\":{\"fname\": \"donut.jpg\",\"w\": 200,\"h\": 200},\"thumbnail\":{\"fname\": \"donutThumb.jpg\",\"w\": 32,\"h\": 32}}"

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

# The top-level JSON object has three members: name, image, and thumbnail.
set nameIndex [CkJsonObject_IndexOf $json "name"]
# The index of the "name" member is 0.
puts "nameIndex = $nameIndex"

set thumbIndex [CkJsonObject_IndexOf $json "thumbnail"]
# The index of the "thumbnail" member is 2.
puts "thumbIndex = $thumbIndex"

# The "fname" member is NOT a direct member of the top-level JSON object.
# It is a member of a nested object.  If we try to get the index of this
# member using the top-level JSON object, it is not found (and returns -1).
set fnameIndex [CkJsonObject_IndexOf $json "fname"]
# The fnameIndex is -1 (not found).  This is correct.
puts "fnameIndex = $fnameIndex"

# Get the "image" object.
set imageObj [new_CkJsonObject]

CkJsonObject_ObjectOf2 $json "image" $imageObj

# Now we can get the index of the "fname" object, because it is a direct
# member of the "image" object:
set fnameIndex [CkJsonObject_IndexOf $imageObj "fname"]
puts "fnameIndex = $fnameIndex"

delete_CkJsonObject $json
delete_CkJsonObject $imageObj