Add SchemaField serialization and deserialization. (#3786)

bigquery/google/cloud/bigquery/schema.py

@@ -43,6 +43,25 @@ def __init__(self, name, field_type, mode='NULLABLE',
  self._description = description
  self._fields = tuple(fields)
 
+ @classmethod
+ def from_api_repr(cls, api_repr):
+ """Return a ``SchemaField`` object deserialized from a dictionary.
+
+ Args:
+ api_repr (Mapping[str, str]): The serialized representation
+ of the SchemaField, such as what is output by
+ :meth:`to_api_repr`.
+
+ Returns:
+ SchemaField: The ``SchemaField`` object.
+ """
+ return cls(
+ field_type=api_repr['type'].upper(),
+ fields=[cls.from_api_repr(f) for f in api_repr.get('fields', ())],
+ mode=api_repr['mode'].upper(),
+ name=api_repr['name'],
+ )
+
  @property
  def name(self):
  """str: The name of the field."""
@@ -84,6 +103,28 @@ def fields(self):
  """
  return self._fields
 
+ def to_api_repr(self):
+ """Return a dictionary representing this schema field.
+
+ Returns:
+ dict: A dictionary representing the SchemaField in a serialized
+ form.
+ """
+ # Put together the basic representation. See http://bit.ly/2hOAT5u.
+ answer = {
+ 'mode': self.mode.lower(),
+ 'name': self.name,
+ 'type': self.field_type.lower(),
+ }
+
+ # If this is a RECORD type, then sub-fields are also included,
+ # add this to the serialized representation.
+ if self.field_type.upper() == 'RECORD':
+ answer['fields'] = [f.to_api_repr() for f in self.fields]
+
+ # Done; return the serialized dictionary.
+ return answer
+
  def _key(self):
  """A tuple key that unique-ly describes this field.
 

bigquery/tests/unit/test_schema.py

@@ -61,6 +61,47 @@ def test_constructor_subfields(self):
  self.assertIs(field._fields[0], sub_field1)
  self.assertIs(field._fields[1], sub_field2)
 
+ def test_to_api_repr(self):
+ field = self._make_one('foo', 'INTEGER', 'NULLABLE')
+ self.assertEqual(field.to_api_repr(), {
+ 'mode': 'nullable',
+ 'name': 'foo',
+ 'type': 'integer',
+ })
+
+ def test_to_api_repr_with_subfield(self):
+ subfield = self._make_one('bar', 'INTEGER', 'NULLABLE')
+ field = self._make_one('foo', 'RECORD', 'REQUIRED', fields=(subfield,))
+ self.assertEqual(field.to_api_repr(), {
+ 'fields': [{
+ 'mode': 'nullable',
+ 'name': 'bar',
+ 'type': 'integer',
+ }],
+ 'mode': 'required',
+ 'name': 'foo',
+ 'type': 'record',
+ })
+
+ def test_from_api_repr(self):
+ field = self._get_target_class().from_api_repr({
+ 'fields': [{
+ 'mode': 'nullable',
+ 'name': 'bar',
+ 'type': 'integer',
+ }],
+ 'mode': 'required',
+ 'name': 'foo',
+ 'type': 'record',
+ })
+ self.assertEqual(field.name, 'foo')
+ self.assertEqual(field.field_type, 'RECORD')
+ self.assertEqual(field.mode, 'REQUIRED')
+ self.assertEqual(len(field.fields), 1)
+ self.assertEqual(field.fields[0].name, 'bar')
+ self.assertEqual(field.fields[0].field_type, 'INTEGER')
+ self.assertEqual(field.fields[0].mode, 'NULLABLE')
+
  def test_name_property(self):
  name = 'lemon-ness'
  schema_field = self._make_one(name, 'INTEGER')