feat: Add Field class

sdk/python/feast/field.py

@@ -0,0 +1,84 @@
+# Copyright 2022 The Feast Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from feast.feature import Feature
+from feast.protos.feast.core.Feature_pb2 import FeatureSpecV2 as FieldProto
+from feast.types import FeastType, from_value_type
+
+
+class Field:
+    """
+    A Field represents a set of values with the same structure.
+
+    Attributes:
+        name: The name of the field.
+        dtype: The type of the field, such as string or float.
+    """
+
+    name: str
+    dtype: FeastType
+
+    def __init__(
+        self, *, name: str, dtype: FeastType,
+    ):
+        """
+        Creates a Field object.
+
+        Args:
+            name: The name of the field.
+            dtype: The type of the field, such as string or float.
+        """
+        self.name = name
+        self.dtype = dtype
+
+    def __eq__(self, other):
+        if self.name != other.name or self.dtype != other.dtype:
+            return False
+        return True
+
+    def __hash__(self):
+        return hash((self.name, hash(self.dtype)))
+
+    def __lt__(self, other):
+        return self.name < other.name
+
+    def __repr__(self):
+        return f"{self.name}-{self.dtype}"
+
+    def __str__(self):
+        return f"Field(name={self.name}, dtype={self.dtype})"
+
+    def to_proto(self) -> FieldProto:
+        """Converts a Field object to its protobuf representation."""
+        return FieldProto(name=self.name, value_type=self.dtype.to_value_type())
+
+    @classmethod
+    def from_proto(cls, field_proto: FieldProto):
+        """
+        Creates a Field object from a protobuf representation.
+
+        Args:
+            field_proto: FieldProto protobuf object
+        """
+        return cls(name=field_proto.name, dtype=from_value_type(field_proto.value_type))
+
+    @classmethod
+    def from_feature(cls, feature: Feature):
+        """
+        Creates a Field object from a Feature object.
+
+        Args:
+            feature: Feature object to convert.
+        """
+        return cls(name=feature.name, dtype=from_value_type(feature.dtype.value))

sdk/python/feast/types.py

@@ -46,6 +46,9 @@ def to_value_type(self) -> ValueTypeProto.Enum:
         """
         raise NotImplementedError
 
+    def __hash__(self):
+        return hash(self.to_value_type())
+
     def __eq__(self, other):
         return self.to_value_type() == other.to_value_type()
 
@@ -75,6 +78,9 @@ def to_value_type(self) -> ValueTypeProto.Enum:
         value_type_name = PRIMITIVE_FEAST_TYPES_TO_VALUE_TYPES[self.name]
         return ValueTypeProto.Enum.Value(value_type_name)
 
+    def __str__(self):
+        return PRIMITIVE_FEAST_TYPES_TO_STRING[self.name]
+
 
 Invalid = PrimitiveFeastType.INVALID
 Bytes = PrimitiveFeastType.BYTES
@@ -99,6 +105,18 @@ def to_value_type(self) -> ValueTypeProto.Enum:
     UnixTimestamp,
 ]
 
+PRIMITIVE_FEAST_TYPES_TO_STRING = {
+    "INVALID": "Invalid",
+    "STRING": "String",
+    "BYTES": "Bytes",
+    "BOOL": "Bool",
+    "INT32": "Int32",
+    "INT64": "Int64",
+    "FLOAT32": "Float32",
+    "FLOAT64": "Float64",
+    "UNIX_TIMESTAMP": "UnixTimestamp",
+}
+
 
 class Array(ComplexFeastType):
     """
@@ -124,10 +142,14 @@ def to_value_type(self) -> int:
         value_type_list_name = value_type_name + "_LIST"
         return ValueTypeProto.Enum.Value(value_type_list_name)
 
+    def __str__(self):
+        return f"Array({self.base_type})"
+
+
+FeastType = Union[ComplexFeastType, PrimitiveFeastType]
+
 
-VALUE_TYPES_TO_FEAST_TYPES: Dict[
-    "ValueTypeProto.Enum", Union[ComplexFeastType, PrimitiveFeastType]
-] = {
+VALUE_TYPES_TO_FEAST_TYPES: Dict["ValueTypeProto.Enum", FeastType] = {
     ValueTypeProto.Enum.INVALID: Invalid,
     ValueTypeProto.Enum.BYTES: Bytes,
     ValueTypeProto.Enum.STRING: String,
@@ -148,9 +170,7 @@ def to_value_type(self) -> int:
 }
 
 
-def from_value_type(
-    value_type: ValueTypeProto.Enum,
-) -> Union[ComplexFeastType, PrimitiveFeastType]:
+def from_value_type(value_type: ValueTypeProto.Enum,) -> FeastType:
     """
     Converts a ValueTypeProto.Enum to a Feast type.