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$jsonExists

$jsonExists checks if a key exists in the current JSON object. Returns true if it does, false if it does not.

Syntax

$jsonExists[Key;...]

• Key: one or more keys forming the path to check.

Returns empty if no $jsonParse or $jsonSet was called, or $jsonClear was called.

What happens

1. $jsonParse loads the JSON object into memory.
2. $jsonExists checks whether the key at the given path exists.
3. Returns true or false.

Example 1: Check a key

$nomention
$jsonParse[{"username":"Zubariel"}]
$jsonExists[username]
$jsonExists[tag]

What happens:

1. $jsonParse loads the object which has username but no tag.
2. $jsonExists[username] returns true.
3. $jsonExists[tag] returns false.

Output:

true
false

Example 2: Use inside a condition

$nomention
$jsonParse[{"role":"admin"}]
$if[$jsonExists[role]==true]
Role: $json[role]
$else
No role set.
$endif

What happens:

1. $jsonParse loads the object.
2. $jsonExists[role] returns true, so the $if block runs.
3. $json[role] returns admin.

Output:

Role: admin

Common uses

• Validating before reading: confirm a key exists before calling $json on it
• Conditional logic: branch behaviour based on whether a field is present
• Array checks: verify a nested key exists before appending to it

See also

• $json: to read the value once confirmed it exists
• $jsonUnset: to remove a key after checking it exists