[enh] #59 use graphql-core library to validate GraphQL queries against server schema

Add graphql-core >= 3 and python >= 3.6 dependencies

examples/request_graphql.py

 import asyncio
+import sys
 
 from duniterpy.api.client import Client
+from graphql import get_introspection_query, build_client_schema, language, validate
+from graphql.error import GraphQLSyntaxError
 
 # CONFIG #######################################
 
 # You can either use a complete defined endpoint : [NAME_OF_THE_API] [DOMAIN] [IPv4] [IPv6] [PORT]
 # or the simple definition : [NAME_OF_THE_API] [DOMAIN] [PORT]
-# Here we use the secure BASIC_MERKLED_API (BMAS)
+# Here we use the secure BASIC_MERKLED_API (BMAS) for standard http over ssl requests
 SWAPI_ENDPOINT = "BMAS swapi.graph.cool 443"
 
 
@@ -16,6 +19,15 @@ SWAPI_ENDPOINT = "BMAS swapi.graph.cool 443"
 async def main():
     client = Client(SWAPI_ENDPOINT)
 
+    # get query to get schema from api
+    query = get_introspection_query(False)
+    # get schema from api
+    response = await client.query(query)
+    print(response)
+    # convert response dict to schema
+    schema = build_client_schema(response["data"])
+
+    # create all films query
     query = """query {
        allFilms {
         title,
@@ -25,7 +37,21 @@ async def main():
       }
      }
     """
+    # check query syntax
+    try:
+        ast_document = language.parse(query)
+    except GraphQLSyntaxError as exception:
+        print("Query syntax error: {0}".format(exception.message))
+        sys.exit(1)
+
+    # validate query against schema
+    errors = validate(schema, ast_document)
+    if errors:
+        print("Schema errors:")
+        print(errors)
+        sys.exit(1)
 
+    # send valid query to api
     response = await client.query(query)
     print(response)
 

requirements.txt

@@ -6,3 +6,4 @@ jsonschema >= 2.6.0
 pypeg2 >=2.15.2
 attr >=0.3.1
 pyaes >=1.6.1
+graphql-core >=3
\ No newline at end of file