diff options
Diffstat (limited to 'docs/howto')
| -rw-r--r-- | docs/howto/custom-model-fields.txt | 37 |
1 files changed, 11 insertions, 26 deletions
diff --git a/docs/howto/custom-model-fields.txt b/docs/howto/custom-model-fields.txt index d1b7dddc8b..6b164803d0 100644 --- a/docs/howto/custom-model-fields.txt +++ b/docs/howto/custom-model-fields.txt @@ -108,11 +108,11 @@ What does a field class do? All of Django's fields (and when we say *fields* in this document, we always mean model fields and not :ref:`form fields <ref-forms-fields>`) are subclasses of :class:`django.db.models.Field`. Most of the information that Django records -about a field is common to all fields -- name, help text, validator lists, -uniqueness and so forth. Storing all that information is handled by ``Field``. -We'll get into the precise details of what ``Field`` can do later on; for now, -suffice it to say that everything descends from ``Field`` and then customizes -key pieces of the class behavior. +about a field is common to all fields -- name, help text, uniqueness and so +forth. Storing all that information is handled by ``Field``. We'll get into the +precise details of what ``Field`` can do later on; for now, suffice it to say +that everything descends from ``Field`` and then customizes key pieces of the +class behavior. It's important to realize that a Django field class is not what is stored in your model attributes. The model attributes contain normal Python objects. The @@ -210,7 +210,6 @@ parameters: * :attr:`~django.db.models.Field.unique_for_date` * :attr:`~django.db.models.Field.unique_for_month` * :attr:`~django.db.models.Field.unique_for_year` - * :attr:`~django.db.models.Field.validator_list` * :attr:`~django.db.models.Field.choices` * :attr:`~django.db.models.Field.help_text` * :attr:`~django.db.models.Field.db_column` @@ -567,33 +566,19 @@ output in some other place, outside of Django. Converting field data for serialization ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -.. method:: flatten_data(self, follow, obj=None) - -.. admonition:: Subject to change - - Although implementing this method is necessary to allow field - serialization, the API might change in the future. - -Returns a dictionary, mapping the field's attribute name to a flattened string -version of the data. This method has some internal uses that aren't of interest -to use here (mostly having to do with forms). For our purposes, it's sufficient -to return a one item dictionary that maps the attribute name to a string. +.. method:: value_to_string(self, obj) This method is used by the serializers to convert the field into a string for -output. You can ignore the input parameters for serialization purposes, although -calling :meth:`Field._get_val_from_obj(obj) -<django.db.models.Field._get_val_from_obj>` is the best way to get the value to -serialize. - -For example, since our ``HandField`` uses strings for its data storage anyway, -we can reuse some existing conversion code:: +output. Calling :meth:``Field._get_val_from_obj(obj)`` is the best way to get the +value to serialize. For example, since our ``HandField`` uses strings for its +data storage anyway, we can reuse some existing conversion code:: class HandField(models.Field): # ... - def flatten_data(self, follow, obj=None): + def value_to_string(self, obj): value = self._get_val_from_obj(obj) - return {self.attname: self.get_db_prep_value(value)} + return self.get_db_prep_value(value) Some general advice -------------------- |