1 files changed, 125 insertions, 0 deletions
diff --git a/libs/flask_restx/schemas/__init__.py b/libs/flask_restx/schemas/__init__.py
new file mode 100644
index 000000000..d6dc2ac0f
--- /dev/null
+++ b/libs/flask_restx/schemas/__init__.py
@@ -0,0 +1,125 @@
+# -*- coding: utf-8 -*-
+"""
+This module give access to OpenAPI specifications schemas
+and allows to validate specs against them.
+
+.. versionadded:: 0.12.1
+"""
+from __future__ import unicode_literals
+
+import io
+import json
+import pkg_resources
+
+try:
+    from collections.abc import Mapping
+except ImportError:
+    # TODO Remove this to drop Python2 support
+    from collections import Mapping
+from jsonschema import Draft4Validator
+
+from flask_restx import errors
+
+
+class SchemaValidationError(errors.ValidationError):
+    """
+    Raised when specification is not valid
+
+    .. versionadded:: 0.12.1
+    """
+
+    def __init__(self, msg, errors=None):
+        super(SchemaValidationError, self).__init__(msg)
+        self.errors = errors
+
+    def __str__(self):
+        msg = [self.msg]
+        for error in sorted(self.errors, key=lambda e: e.path):
+            path = ".".join(error.path)
+            msg.append("- {}: {}".format(path, error.message))
+            for suberror in sorted(error.context, key=lambda e: e.schema_path):
+                path = ".".join(suberror.schema_path)
+                msg.append("  - {}: {}".format(path, suberror.message))
+        return "\n".join(msg)
+
+    __unicode__ = __str__
+
+
+class LazySchema(Mapping):
+    """
+    A thin wrapper around schema file lazy loading the data on first access
+
+    :param filename str: The package relative json schema filename
+    :param validator: The jsonschema validator class version
+
+    .. versionadded:: 0.12.1
+    """
+
+    def __init__(self, filename, validator=Draft4Validator):
+        super(LazySchema, self).__init__()
+        self.filename = filename
+        self._schema = None
+        self._validator = validator
+
+    def _load(self):
+        if not self._schema:
+            filename = pkg_resources.resource_filename(__name__, self.filename)
+            with io.open(filename) as infile:
+                self._schema = json.load(infile)
+
+    def __getitem__(self, key):
+        self._load()
+        return self._schema.__getitem__(key)
+
+    def __iter__(self):
+        self._load()
+        return self._schema.__iter__()
+
+    def __len__(self):
+        self._load()
+        return self._schema.__len__()
+
+    @property
+    def validator(self):
+        """The jsonschema validator to validate against"""
+        return self._validator(self)
+
+
+#: OpenAPI 2.0 specification schema
+OAS_20 = LazySchema("oas-2.0.json")
+
+#: Map supported OpenAPI versions to their JSON schema
+VERSIONS = {
+    "2.0": OAS_20,
+}
+
+
+def validate(data):
+    """
+    Validate an OpenAPI specification.
+
+    Supported OpenAPI versions: 2.0
+
+    :param data dict: The specification to validate
+    :returns boolean: True if the specification is valid
+    :raises SchemaValidationError: when the specification is invalid
+    :raises flask_restx.errors.SpecsError: when it's not possible to determinate
+                                              the schema to validate against
+
+    .. versionadded:: 0.12.1
+    """
+    if "swagger" not in data:
+        raise errors.SpecsError("Unable to determinate OpenAPI schema version")
+
+    version = data["swagger"]
+    if version not in VERSIONS:
+        raise errors.SpecsError('Unknown OpenAPI schema version "{}"'.format(version))
+
+    validator = VERSIONS[version].validator
+
+    validation_errors = list(validator.iter_errors(data))
+    if validation_errors:
+        raise SchemaValidationError(
+            "OpenAPI {} validation failed".format(version), errors=validation_errors
+        )
+    return True