Docs: Describe how complex types are serialized/deserialized.

docs/source/index.rst

@@ -17,6 +17,7 @@ Contents
 
    introduction
    crud
+   serialization
    searching
    content-negotiation
    http-status-codes

docs/source/serialization.rst

@@ -0,0 +1,141 @@
+=============
+Serialization
+=============
+
+Throughout the REST API, content needs to be serialized and deserialized
+to and from JSON representations.
+
+In general, the format used for serializing content when reading from the API
+is the same as is used to submit content to the API for writing.
+
+Basic Types
+===========
+
+Basic Python data types that have a corresponding type in JSON, like integers
+or strings, will simply be translated between the Python type and the
+respective JSON type.
+
+Dates and Times
+===============
+
+Since JSON doesn't have native support for dates/times, the Python/Zope
+datetime types will be serialized to an ISO 8601 datestring.
+
+======================================= ======================================
+Python                                  JSON
+======================================= ======================================
+``time(19, 45, 55)``                    ``'19:45:55'``
+``date(2015, 11, 23)``                  ``'2015-11-23'``
+``datetime(2015, 11, 23, 19, 45, 55)``  ``'2015-11-23T19:45:55'``
+``DateTime('2015/11/23 19:45:55')``     ``'2015-11-23T19:45:55'``
+======================================= ======================================
+
+
+RichText fields
+===============
+
+RichText fields will be serialized as follows:
+
+A ``RichTextValue`` like
+
+.. code:: python
+
+    RichTextValue(u'<p>Hallöchen</p>',
+                  mimeType='text/html',
+                  outputMimeType='text/html')
+
+will be serialized to
+
+.. code:: json
+
+    {
+      "data": "<p>Hall\u00f6chen</p>",
+      "content-type": "text/html",
+      "encoding": "utf-8"
+    }
+
+File Fields
+===========
+
+Download (serialization)
+------------------------
+
+For download, the file field will simply be serialized to a string that
+contains the download URL for the file.
+
+.. code:: json
+
+      {
+        "...": "",
+        "@type": "File",
+        "title": "My file",
+        "file": "http://localhost:55001/plone/file/@@download/file"
+      }
+
+That URL points to the regular Plone
+download view.
+
+This means that when accessing that URL, your request won't be handled by
+the API but a regular Plone browser view. Therefore you must **not** send
+the ``Accept: application/json`` header in this case.
+
+Upload (deserialization)
+------------------------
+
+For a field of type ``Named[Blob]File`` (Dexterity) or ``FileField``
+(Archetypes), represent the field content as a dictionary with these four keys:
+
+- ``data`` - the base64 encoded contents of the file
+- ``encoding`` - the encoding you used to encode the data, so usually `base64`
+- ``content-type`` - the MIME type of the file
+- ``filename`` - the name of the file, including extension
+
+.. code:: json
+
+      {
+        "...": "",
+        "@type": "File",
+        "title": "My file",
+        "file": {
+            "data": "TG9yZW0gSXBzdW0uCg==",
+            "encoding": "base64",
+            "filename": "lorem.txt",
+            "content-type": "text/plain"}
+      }
+
+
+Relations
+=========
+
+Serialization
+-------------
+
+A ``RelationValue`` will be serialized to a short summary representation of
+the referenced object:
+
+.. code:: json
+
+    {
+      '@id': 'http://nohost/plone/doc1',
+      '@type': 'DXTestDocument',
+      'title': 'Document 1',
+      'description': 'Description'
+    }
+
+The ``RelationList`` containing that reference will be represended as a list
+in JSON.
+
+Deserialization
+---------------
+
+In order to set a relation when creating or updating content, you can use one
+of several ways to specify relations:
+
+======================================= ======================================
+Type                                    Example
+======================================= ======================================
+UID                                     ``'9b6a4eadb9074dde97d86171bb332ae9'``
+IntId                                   ``123456``
+Path                                    ``'/plone/doc1'``
+URL                                     ``'http://localhost:8080/plone/doc1'``
+======================================= ======================================