1 files changed, 215 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..be72e444
--- /dev/null
+++ b/rest_framework/utils/field_mapping.py
@@ -0,0 +1,215 @@
+"""
+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
+import inspect
+
+
+def lookup_class(mapping, instance):
+    """
+    Takes a dictionary with classes as keys, and an object.
+    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.
+    """
+    for cls in inspect.getmro(instance.__class__):
+        if cls in mapping:
+            return mapping[cls]
+    raise KeyError('Class %s not found in lookup.', cls.__name__)
+
+
+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 = model_field.validators
+
+    if model_field.null or model_field.blank:
+        kwargs['required'] = False
+
+    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
+
+    if isinstance(model_field, models.AutoField) or not model_field.editable:
+        kwargs['read_only'] = True
+        # Read only implies that the field is not required.
+        # We have a cleaner repr on the instance if we don't set it.
+        kwargs.pop('required', None)
+
+    if model_field.has_default():
+        kwargs['default'] = model_field.get_default()
+        # Having a default implies that the field is not required.
+        # We have a cleaner repr on the instance if we don't set it.
+        kwargs.pop('required', None)
+
+    if model_field.flatchoices:
+        # If this model field contains choices, then return now,
+        # any 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:
+        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 = getattr(model_field, 'min_length', None)
+    if min_length is not None:
+        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:
+        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:
+        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
+        ]
+
+    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.BooleanField):
+        # models.BooleanField has `blank=True`, but *is* actually
+        # required *unless* a default is provided.
+        # Also note that Django<1.6 uses `default=False` for
+        # models.BooleanField, but Django>=1.6 uses `default=None`.
+        kwargs.pop('required', None)
+
+    if validator_kwarg:
+        kwargs['validators'] = validator_kwarg
+
+    # The following will only be used by ModelField classes.
+    # Gets removed for everything else.
+    kwargs['model_field'] = model_field
+
+    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.null or model_field.blank:
+            kwargs['required'] = False
+        if model_field.verbose_name and needs_label(model_field, field_name):
+            kwargs['label'] = capfirst(model_field.verbose_name)
+        if not model_field.editable:
+            kwargs['read_only'] = True
+            kwargs.pop('queryset', None)
+        help_text = clean_manytomany_helptext(model_field.help_text)
+        if help_text:
+            kwargs['help_text'] = help_text
+
+    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)
+    }