JSON Functions
PHP Manual

json_validate

Checks if a string contains valid JSON

Description

bool json_validate(string $json, int $depth = 512, int $flags = 0)

Returns whether the given string is syntactically valid JSON. If json_validate returns true, json_decode will successfully decode the given string when using the same depth and flags.

If json_validate returns false, the cause can be retrieved using json_last_error and json_last_error_msg.

json_validate uses less memory than json_decode if the decoded JSON payload is not used, because it does not need to build the array or object structure containing the payload.

Caution

Calling json_validate immediately before json_decode will unnecessarily parse the string twice, as json_decode implicitly performs validation during decoding.

json_validate should therefore only be used if the decode JSON payload is not immediately used and knowing whether the string contains valid JSON is needed.

Parameters

json

The string to validate.

This function only works with UTF-8 encoded strings.

Note:

PHP implements a superset of JSON as specified in the original » RFC 7159.

depth

Maximum nesting depth of the structure being decoded. The value must be greater than 0, and less than or equal to 2147483647.

flags

Currently only JSON_INVALID_UTF8_IGNORE is accepted.

Return Values

Returns true if the given string is syntactically valid JSON, otherwise returns false.

Errors/Exceptions

If depth is outside the allowed range, a ValueError is thrown.

If flags is not a valid flag, a ValueError is thrown.

Examples

Example #1 json_validate examples

<?php
var_dump(json_validate('{ "test": { "foo": "bar" } }'));
var_dump(json_validate('{ "": "": "" } }'));
?>

The above example will output:

bool(true)
bool(false)

See Also

  • json_decode
  • json_last_error
  • json_last_error_msg