Merge pull request #33 from alexei/feature/fields

Implement various fields

Author: alexei

adapter/__init__.py

@@ -0,0 +1,6 @@
+# -*- coding: utf-8 -*-
+
+from __future__ import absolute_import
+
+from .adapters import *  # noqa
+from .fields import *  # noqa

adapter/adapter.py

@@ -0,0 +1,57 @@
+# -*- coding: utf-8 -*-
+
+from __future__ import unicode_literals
+from __future__ import absolute_import
+
+import collections
+import copy
+import six
+
+from .base import BaseField
+from .meta import AdapterMetaClass
+from .utils import BindingDict
+from .utils import undefined
+
+
+__all__ = ['Adapter']
+
+
+@six.add_metaclass(AdapterMetaClass)
+class Adapter(BaseField):
+    def __init__(self, data=None, instance=None, *args, **kwargs):
+        self.data = data
+        self.instance = instance
+
+        super(Adapter, self).__init__(*args, **kwargs)
+
+    @property
+    def fields(self):
+        if not hasattr(self, '_fields'):
+            self._fields = BindingDict(self)
+            for key, value in self.get_fields().iteritems():
+                self._fields[key] = value
+        return self._fields
+
+    def get_fields(self):
+        return copy.deepcopy(self.declared_fields)
+
+    def adapt(self, data=None):
+        instance = self.get_instance()
+        for field_name, field in self.fields.iteritems():
+            value = field.get_attribute(data or self.data)
+            if value is undefined:
+                continue
+            adapted_value = field.adapt(value)
+            if isinstance(instance, collections.Mapping):
+                instance[field_name] = adapted_value
+            else:
+                setattr(instance, field_name, adapted_value)
+        return instance
+
+    def get_instance(self):
+        if self.instance:
+            return self.instance
+        else:
+            meta = getattr(self, 'Meta', None)
+            model_cls = getattr(meta, 'model', dict)
+            return model_cls()

adapters/__init__.py

@@ -0,0 +1,57 @@
+# -*- coding: utf-8 -*-
+
+from __future__ import unicode_literals
+from __future__ import absolute_import
+
+from .helpers import get_attribute
+from .utils import undefined
+
+
+class BaseField(object):
+    def __init__(self, source=None, default=undefined, required=True):
+        self.source = source
+        self.default = default
+        self.required = required
+
+    def bind(self, field_name, adapter):
+        if field_name == self.source:
+            raise ValueError((
+                "The `source='{field_name}'` kwarg is redundant on "
+                "field `{adapter_name}.{field_name}`. "
+                "Remove the `source` kwarg."
+            ).format(
+                field_name=field_name,
+                adapter_name=adapter.__class__.__name__,
+            ))
+
+        self.field_name = field_name
+        self.adapter = adapter
+
+        if self.source is None:
+            self.source = self.field_name
+
+        if self.source == '*':
+            self.lookup_attrs = []
+        else:
+            self.lookup_attrs = self.source.split('.')
+
+    def get_attribute(self, obj):
+        value = get_attribute(obj, self.lookup_attrs)
+        if value is undefined:
+            if self.default is not undefined:
+                return self.default
+            elif self.required:
+                raise ValueError((
+                    "Required value not found for field "
+                    "`{adapter_name}.{field_name}`. Provide a default value."
+                ).format(
+                    adapter_name=self.adapter.__class__.__name__,
+                    field_name=self.field_name,
+                ))
+            else:
+                return undefined
+        else:
+            return value
+
+    def adapt(self, data):
+        return data

adapters/adapters.py

@@ -0,0 +1,53 @@
+# -*- coding: utf-8 -*-
+
+from __future__ import unicode_literals
+
+import datetime
+import dateutil.parser
+from decimal import Decimal
+
+from .base import BaseField
+
+
+__all__ = [
+    'BooleanField', 'CharField', 'DecimalField', 'Field', 'FloatField',
+    'IntField', 'TimeField']
+
+
+class BooleanField(BaseField):
+    def adapt(self, data):
+        return bool(data)
+
+
+class CharField(BaseField):
+    def adapt(self, data):
+        return unicode(data)
+
+
+class DecimalField(BaseField):
+    def adapt(self, data):
+        return Decimal(data)
+
+
+class Field(BaseField):
+    pass
+
+
+class FloatField(BaseField):
+    def adapt(self, data):
+        return float(data)
+
+
+class IntField(BaseField):
+    def adapt(self, data):
+        return int(data)
+
+
+class TimeField(BaseField):
+    def adapt(self, data):
+        if isinstance(data, datetime.time):
+            return data
+        elif isinstance(data, (str, unicode)):
+            return dateutil.parser.parse(data).timetz()
+        else:
+            raise ValueError("Invalid time argument")

adapters/base.py

@@ -0,0 +1,32 @@
+# -*- coding: utf-8 -*-
+
+from __future__ import unicode_literals
+from __future__ import absolute_import
+
+import collections
+
+from .utils import undefined
+
+
+__all__ = ['get_attribute']
+
+
+def get_attribute(obj, attrs):
+    for attr in attrs:
+        if obj is None:
+            return undefined
+
+        try:
+            if isinstance(obj, collections.Mapping):
+                obj = obj[attr]
+            elif isinstance(obj, collections.Iterable):
+                obj = obj[int(attr)]
+            else:
+                obj = getattr(obj, attr)
+        except Exception:
+            return undefined
+
+        if callable(obj):
+            obj = obj()
+
+    return obj