Advanced Usage of Zend_JsonJSON ObjectsWhen encoding PHP objects as JSON, all public properties of that object will be encoded in a JSON object. JSON does not allow object references, so care should be taken not to encode objects with recursive references. If you have issues with recursion, Zend_Json::encode() and Zend_Json_Encoder::encode() allow an optional second parameter to check for recursion; if an object is serialized twice, an exception will be thrown. Decoding JSON objects poses an additional difficulty, however, since Javascript objects correspond most closely to PHP's associative array. Some suggest that a class identifier should be passed, and an object instance of that class should be created and populated with the key/value pairs of the JSON object; others feel this could pose a substantial security risk. By default, Zend_Json will decode JSON objects as associative arrays. However, if you desire an object returned, you can specify this:
Any objects thus decoded are returned as The recommendation of Zend Framework is that the individual developer should decide how to decode JSON objects. If an object of a specified type should be created, it can be created in the developer code and populated with the values decoded using Zend_Json. Encoding PHP objectsIf you are encoding PHP objects by default the encoding mechanism can only access public properties of these objects. When a method toJson() is implemented on an object to encode, Zend_Json calls this method and expects the object to return a JSON representation of its internal state. Internal Encoder/DecoderZend_Json has two different modes depending if ext/json is enabled in your PHP installation or not. If ext/json is installed by default json_encode() and json_decode() functions are used for encoding and decoding JSON. If ext/json is not installed a Zend Framework implementation in PHP code is used for en-/decoding. This is considerably slower than using the php extension, but behaves exactly the same. Still sometimes you might want to use the internal encoder/decoder even if you have ext/json installed. You can achieve this by calling:
JSON ExpressionsJavascript makes heavy use of anonymnous function callbacks, which can be saved within JSON object variables. Still they only work if not returned inside double qoutes, which Zend_Json naturally does. With the Expression support for Zend_Json support you can encode JSON objects with valid javascript callbacks. This works for both json_encode() or the internal encoder.
A javascript callback is represented using the Zend_Json_Expr object.
It implements the value object pattern and is immutable. You can set the javascript
expression as the first constructor argument. By default Zend_Json::encode
does not encode javascript callbacks, you have to pass the option
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