Tcl

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. Tcl

load ./chilkat.dll

set success 0

set json [new_CkJsonObject]

# First build simple JSON..
CkJsonObject_UpdateInt $json "test.abc" 100

CkJsonObject_put_EmitCompact $json 0
puts [CkJsonObject_emit $json]

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

set path "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?
set val [CkJsonObject_IntOf $json $path]
puts "val = $val"

# 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..
set wasFound [CkJsonObject_get_LastMethodSuccess $json]
puts "wasFound = $wasFound (not a valid indicator)"

# Instead, if the returned value is 0, we can double-check to see if the member was truly there..
if {$val == 0} then {
    set wasFound [CkJsonObject_HasMember $json $path]
    puts "wasFound = $wasFound"
    if {$wasFound == 1} then {
        puts "The value was present and is 0."
    }     else {
        puts "no member is present at test.notHere"
    }

} else {
    puts "val = $val"
}

# Alternatively, you could check to see if the member exists beforehand..
if {[CkJsonObject_HasMember $json $path] == 1} then {
    puts "val = [CkJsonObject_IntOf $json $path]"
} else {
    puts "no member at $path"
}


delete_CkJsonObject $json