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Diffstat (limited to 'rest_framework/utils/field_mapping.py')
| -rw-r--r-- | rest_framework/utils/field_mapping.py | 249 |
1 files changed, 249 insertions, 0 deletions
diff --git a/rest_framework/utils/field_mapping.py b/rest_framework/utils/field_mapping.py new file mode 100644 index 00000000..c97ec5d0 --- /dev/null +++ b/rest_framework/utils/field_mapping.py @@ -0,0 +1,249 @@ +""" +Helper functions for mapping model fields to a dictionary of default +keyword arguments that should be used for their equivelent serializer fields. +""" +from django.core import validators +from django.db import models +from django.utils.text import capfirst +from rest_framework.compat import clean_manytomany_helptext +from rest_framework.validators import UniqueValidator +import inspect + + +NUMERIC_FIELD_TYPES = ( + models.IntegerField, models.FloatField, models.DecimalField +) + + +class ClassLookupDict(object): + """ + Takes a dictionary with classes as keys. + Lookups against this object will traverses the object's inheritance + hierarchy in method resolution order, and returns the first matching value + from the dictionary or raises a KeyError if nothing matches. + """ + def __init__(self, mapping): + self.mapping = mapping + + def __getitem__(self, key): + if hasattr(key, '_proxy_class'): + # Deal with proxy classes. Ie. BoundField behaves as if it + # is a Field instance when using ClassLookupDict. + base_class = key._proxy_class + else: + base_class = key.__class__ + + for cls in inspect.getmro(base_class): + if cls in self.mapping: + return self.mapping[cls] + raise KeyError('Class %s not found in lookup.', cls.__name__) + + def __setitem__(self, key, value): + self.mapping[key] = value + + +def needs_label(model_field, field_name): + """ + Returns `True` if the label based on the model's verbose name + is not equal to the default label it would have based on it's field name. + """ + default_label = field_name.replace('_', ' ').capitalize() + return capfirst(model_field.verbose_name) != default_label + + +def get_detail_view_name(model): + """ + Given a model class, return the view name to use for URL relationships + that refer to instances of the model. + """ + return '%(model_name)s-detail' % { + 'app_label': model._meta.app_label, + 'model_name': model._meta.object_name.lower() + } + + +def get_field_kwargs(field_name, model_field): + """ + Creates a default instance of a basic non-relational field. + """ + kwargs = {} + validator_kwarg = list(model_field.validators) + + # The following will only be used by ModelField classes. + # Gets removed for everything else. + kwargs['model_field'] = model_field + + if model_field.verbose_name and needs_label(model_field, field_name): + kwargs['label'] = capfirst(model_field.verbose_name) + + if model_field.help_text: + kwargs['help_text'] = model_field.help_text + + max_digits = getattr(model_field, 'max_digits', None) + if max_digits is not None: + kwargs['max_digits'] = max_digits + + decimal_places = getattr(model_field, 'decimal_places', None) + if decimal_places is not None: + kwargs['decimal_places'] = decimal_places + + if isinstance(model_field, models.TextField): + kwargs['style'] = {'base_template': 'textarea.html'} + + if isinstance(model_field, models.AutoField) or not model_field.editable: + # If this field is read-only, then return early. + # Further keyword arguments are not valid. + kwargs['read_only'] = True + return kwargs + + if model_field.has_default() or model_field.blank or model_field.null: + kwargs['required'] = False + + if model_field.null and not isinstance(model_field, models.NullBooleanField): + kwargs['allow_null'] = True + + if model_field.blank: + kwargs['allow_blank'] = True + + if model_field.flatchoices: + # If this model field contains choices, then return early. + # Further keyword arguments are not valid. + kwargs['choices'] = model_field.flatchoices + return kwargs + + # Ensure that max_length is passed explicitly as a keyword arg, + # rather than as a validator. + max_length = getattr(model_field, 'max_length', None) + if max_length is not None and isinstance(model_field, models.CharField): + kwargs['max_length'] = max_length + validator_kwarg = [ + validator for validator in validator_kwarg + if not isinstance(validator, validators.MaxLengthValidator) + ] + + # Ensure that min_length is passed explicitly as a keyword arg, + # rather than as a validator. + min_length = next(( + validator.limit_value for validator in validator_kwarg + if isinstance(validator, validators.MinLengthValidator) + ), None) + if min_length is not None and isinstance(model_field, models.CharField): + kwargs['min_length'] = min_length + validator_kwarg = [ + validator for validator in validator_kwarg + if not isinstance(validator, validators.MinLengthValidator) + ] + + # Ensure that max_value is passed explicitly as a keyword arg, + # rather than as a validator. + max_value = next(( + validator.limit_value for validator in validator_kwarg + if isinstance(validator, validators.MaxValueValidator) + ), None) + if max_value is not None and isinstance(model_field, NUMERIC_FIELD_TYPES): + kwargs['max_value'] = max_value + validator_kwarg = [ + validator for validator in validator_kwarg + if not isinstance(validator, validators.MaxValueValidator) + ] + + # Ensure that max_value is passed explicitly as a keyword arg, + # rather than as a validator. + min_value = next(( + validator.limit_value for validator in validator_kwarg + if isinstance(validator, validators.MinValueValidator) + ), None) + if min_value is not None and isinstance(model_field, NUMERIC_FIELD_TYPES): + kwargs['min_value'] = min_value + validator_kwarg = [ + validator for validator in validator_kwarg + if not isinstance(validator, validators.MinValueValidator) + ] + + # URLField does not need to include the URLValidator argument, + # as it is explicitly added in. + if isinstance(model_field, models.URLField): + validator_kwarg = [ + validator for validator in validator_kwarg + if not isinstance(validator, validators.URLValidator) + ] + + # EmailField does not need to include the validate_email argument, + # as it is explicitly added in. + if isinstance(model_field, models.EmailField): + validator_kwarg = [ + validator for validator in validator_kwarg + if validator is not validators.validate_email + ] + + # SlugField do not need to include the 'validate_slug' argument, + if isinstance(model_field, models.SlugField): + validator_kwarg = [ + validator for validator in validator_kwarg + if validator is not validators.validate_slug + ] + + if getattr(model_field, 'unique', False): + validator = UniqueValidator(queryset=model_field.model._default_manager) + validator_kwarg.append(validator) + + if validator_kwarg: + kwargs['validators'] = validator_kwarg + + return kwargs + + +def get_relation_kwargs(field_name, relation_info): + """ + Creates a default instance of a flat relational field. + """ + model_field, related_model, to_many, has_through_model = relation_info + kwargs = { + 'queryset': related_model._default_manager, + 'view_name': get_detail_view_name(related_model) + } + + if to_many: + kwargs['many'] = True + + if has_through_model: + kwargs['read_only'] = True + kwargs.pop('queryset', None) + + if model_field: + if model_field.verbose_name and needs_label(model_field, field_name): + kwargs['label'] = capfirst(model_field.verbose_name) + help_text = clean_manytomany_helptext(model_field.help_text) + if help_text: + kwargs['help_text'] = help_text + if not model_field.editable: + kwargs['read_only'] = True + kwargs.pop('queryset', None) + if kwargs.get('read_only', False): + # If this field is read-only, then return early. + # No further keyword arguments are valid. + return kwargs + if model_field.has_default() or model_field.null: + kwargs['required'] = False + if model_field.null: + kwargs['allow_null'] = True + if model_field.validators: + kwargs['validators'] = model_field.validators + if getattr(model_field, 'unique', False): + validator = UniqueValidator(queryset=model_field.model._default_manager) + kwargs['validators'] = kwargs.get('validators', []) + [validator] + + return kwargs + + +def get_nested_relation_kwargs(relation_info): + kwargs = {'read_only': True} + if relation_info.to_many: + kwargs['many'] = True + return kwargs + + +def get_url_kwargs(model_field): + return { + 'view_name': get_detail_view_name(model_field) + } |