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API reference

Python API


Base class for an adapter object, which defines how telepath should handle a particular Python type. Subclasses should define the following method:

  • pack(obj, context) - Returns a 'deconstructed' version of the object obj, consisting of the data necessary to reconstruct it in JavaScript. This should be a tuple (identifier, args):

    • identifier - the identifier for a JavaScript constructor function that will be registered with the JavaScript register method; this constructor function will be called when an object of this type is encountered in the data. This identifier should be unique among all adapter objects registered; it is recommended to use a namespaced string with dots as separators (e.g. 'myproject.animals.Cat').
    • args - the list of arguments that should be passed to the constructor function to recreate the corresponding client-side object. The arguments must themselves be telepath-packable values (i.e. basic JSON-serialisable types, or objects with a telepath adapter defined).

    The context argument allows the adapter to specify JavaScript and CSS assets that must be included on the client-side page when unpacking the object; at minimum, this should include the JavaScript file that defines and registers the constructor function returned from pack. The context object defines the method:

    • context.add_media(media=None, js=None, css=None) - adds a media definition to include on the client-side page. This can be any of the following: a Django form media object, a single JavaScript file path, a list of JavaScript file paths, and/or a dict of CSS file paths where the key is a media type (i.e. the same convention as used in form media objects).

Alternative adapter API (deprecated)

As an alternative to defining pack, adapter subclasses may define the following:

  • js_constructor - The identifier for a JavaScript constructor function, as above.
  • js_args(obj) - Given the object to be packed, return the list of arguments that should be passed to the constructor function.
  • get_media(obj) - Given the object to be packed, return a Django form media object for the JavaScript and CSS assets needed to unpack the client-side object. This should include the .js file where the constructor function is defined and registered with telepath. Alternatively, if the media definition is the same for all object instances, this can be defined as an inner Media class.


A general-purpose adapter object for classes that define their own packing logic; this is generally the preferred route when making classes you have defined yourself available to telepath, as it is more concise than defining an adapter object explicitly. The class must implement a method telepath_pack(self, context); AutoAdapter will delegate to this when packing the object.

telepath.register(adapter, cls)

Registers an adapter object (an instance of a telepath.Adapter subclass) to be used by telepath when it encounters an object of type cls. If more than one class in an object's inheritance chain has an adapter defined, the most specific one according to the method resolution order (MRO) will be used.

Can also be applied as a class decorator @telepath.register(adapter=MyAdapter()); in this case adapter is optional and defaults to AutoAdapter() if not specified.


An object for handling all packing operations for a particular request. Provides the following methods and attributes:

  • pack(obj) - Returns the packed representation of the given object. This representation is a value that can be serialised as JSON and included in an HTTP response; on the client side this can then be deserialised with JSON.parse and passed to telepath.unpack to obtain the unpacked object.
  • media - A Django form media object listing the JavaScript and CSS assets needed to unpack all objects that have been passed to pack. This object should be rendered into a template response to ensure that the client-side telepath.unpack operation has all the necessary definitions.


An object that manages a set of adapter objects to be used collectively for packing values. Normally you will not need to work with this class directly, as the telepath module maintains a global set of adapters that are registered with the top-level register function and used by JSContext; however, in some cases it may be useful to build a 'local' registry of adapters with different behaviour from the global set, such as serving media from a custom application-specific path. Provides the method register(adapter, cls) which is equivalent to the top-level register function, and the property js_context_class which returns a class equivalent to JSContext that uses this local registry when packing values. The optional telepath_js_path argument specifies the path to telepath.js to be used in this object's media definitions.

JavaScript API


An object that manages unpacking values. Provides the following methods:

  • register(name, constructor) - Registers a constructor function to be used when unpacking. The name argument should match the identifier given as js_constructor for an adapter object.
  • unpack(val) - Unpacks the packed telepath data representation into a native JavaScript object.