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This module contains helper functions for expressing things that wouldotherwise be somewhat verbose or cumbersome using peewee’s APIs. There are alsohelpers for serializing models to dictionaries and vice-versa.

• modelto_dict(_model[, recurse=True[, backrefs=False[, only=None[, exclude=None[, extra_attrs=None[, fields_from_query=None[, max_depth=None[, manytomany=False]]]]]]]])

Parameters:

• recurse (bool) – Whether foreign-keys should be recursed.
• backrefs (bool) – Whether lists of related objects should be recursed.
• only – A list (or set) of field instances which should be included in the result dictionary.
• exclude – A list (or set) of field instances which should be excluded from the result dictionary.
• extra_attrs – A list of attribute or method names on the instance which should be included in the dictionary.
• fields_from_query (Select) – The SelectQuery that created this model instance. Only the fields and values explicitly selected by the query will be serialized.
• max_depth (int) – Maximum depth when recursing.
• manytomany (bool) – Process many-to-many fields.

Convert a model instance (and optionally any related instances) toa dictionary.

Examples:

>>> user = User.create(username='charlie')
>>> model_to_dict(user)
{'id': 1, 'username': 'charlie'}
 
>>> model_to_dict(user, backrefs=True)
{'id': 1, 'tweets': [], 'username': 'charlie'}
 
>>> t1 = Tweet.create(user=user, message='tweet-1')
>>> t2 = Tweet.create(user=user, message='tweet-2')
>>> model_to_dict(user, backrefs=True)
{
  'id': 1,
  'tweets': [
    {'id': 1, 'message': 'tweet-1'},
    {'id': 2, 'message': 'tweet-2'},
  ],
  'username': 'charlie'
}
 
>>> model_to_dict(t1)
{
  'id': 1,
  'message': 'tweet-1',
  'user': {
    'id': 1,
    'username': 'charlie'
  }
}
 
>>> model_to_dict(t2, recurse=False)
{'id': 1, 'message': 'tweet-2', 'user': 1}

The implementation of model_to_dict is fairly complex, owing to thevarious usages it attempts to support. If you have a special usage, Istrongly advise that you do not attempt to shoe-horn some crazycombination of parameters into this function. Just write a simple functionthat accomplishes exactly what you’re attempting to do.

• dictto_model(_model_class, data[, ignore_unknown=False])

Parameters:

• model_class (Model) – The model class to construct.
• data (dict) – A dictionary of data. Foreign keys can be included as nested dictionaries, and back-references as lists of dictionaries.
• ignore_unknown (bool) – Whether to allow unrecognized (non-field) attributes.

Convert a dictionary of data to a model instance, creating relatedinstances where appropriate.

Examples:

>>> user_data = {'id': 1, 'username': 'charlie'}
>>> user = dict_to_model(User, user_data)
>>> user
<__main__.User at 0x7fea8fa4d490>
 
>>> user.username
'charlie'
 
>>> note_data = {'id': 2, 'text': 'note text', 'user': user_data}
>>> note = dict_to_model(Note, note_data)
>>> note.text
'note text'
>>> note.user.username
'charlie'
 
>>> user_with_notes = {
...     'id': 1,
...     'username': 'charlie',
...     'notes': [{'id': 1, 'text': 'note-1'}, {'id': 2, 'text': 'note-2'}]}
>>> user = dict_to_model(User, user_with_notes)
>>> user.notes[0].text
'note-1'
>>> user.notes[0].user.username
'charlie'

• updatemodel_from_dict(_instance, data[, ignore_unknown=False])

Parameters:

• instance (Model) – The model instance to update.
• data (dict) – A dictionary of data. Foreign keys can be included as nested dictionaries, and back-references as lists of dictionaries.
• ignore_unknown (bool) – Whether to allow unrecognized (non-field) attributes.

Update a model instance with the given data dictionary.