1 files changed, 61 insertions, 0 deletions
diff --git a/python-packages/order_utils/src/zero_ex/json_schemas/__init__.py b/python-packages/order_utils/src/zero_ex/json_schemas/__init__.py
new file mode 100644
index 000000000..2a1728b8a
--- /dev/null
+++ b/python-packages/order_utils/src/zero_ex/json_schemas/__init__.py
@@ -0,0 +1,61 @@
+"""JSON schemas and associated utilities."""
+
+from os import path
+import json
+from typing import Mapping
+
+from pkg_resources import resource_string
+import jsonschema
+
+
+def assert_valid(data: Mapping, schema_id: str) -> None:
+    """Validate the given `data` against the specified `schema`.
+
+    :param data: Python dictionary to be validated as a JSON object.
+    :param schema_id: id property of the JSON schema to validate against.  Must
+        be one of those listed in `the 0x JSON schema files
+        <https://github.com/0xProject/0x-monorepo/tree/development/packages/json-schemas/schemas>`_.
+
+    Raises an exception if validation fails.
+
+    >>> assert_valid(
+    ...     {'v': 27, 'r': '0x'+'f'*64, 's': '0x'+'f'*64},
+    ...     '/ECSignature',
+    ... )
+    """
+    # noqa
+    class LocalRefResolver(jsonschema.RefResolver):
+        """Resolve package-local JSON schema id's."""
+
+        def __init__(self):
+            self.ref_to_file = {
+                "/addressSchema": "address_schema.json",
+                "/hexSchema": "hex_schema.json",
+                "/orderSchema": "order_schema.json",
+                "/wholeNumberSchema": "whole_number_schema.json",
+                "/ECSignature": "ec_signature_schema.json",
+                "/ecSignatureParameterSchema": (
+                    "ec_signature_parameter_schema.json" + ""
+                ),
+            }
+            jsonschema.RefResolver.__init__(self, "", "")
+
+        def resolve_from_url(self, url):
+            """Resolve the given URL."""
+            ref = url.replace("file://", "")
+            if ref in self.ref_to_file:
+                return json.loads(
+                    resource_string(
+                        "zero_ex.json_schemas",
+                        f"schemas/{self.ref_to_file[ref]}",
+                    )
+                )
+            raise jsonschema.ValidationError(
+                f"Unknown ref '{ref}'. "
+                + f"Known refs: {list(self.ref_to_file.keys())}."
+            )
+
+    resolver = LocalRefResolver()
+    jsonschema.validate(
+        data, resolver.resolve_from_url(schema_id), resolver=resolver
+    )