add specifiedBy directive (graph-gophers#532)

Author: benzolium

example/social/introspect.json

@@ -70,6 +70,29 @@
           "INLINE_FRAGMENT"
         ],
         "name": "skip"
+      },
+      {
+        "args": [
+          {
+            "defaultValue": null,
+            "description": "The URL should point to a human-readable specification of the data format, serialization, and coercion rules.",
+            "name": "url",
+            "type": {
+              "kind": "NON_NULL",
+              "name": null,
+              "ofType": {
+                "kind": "SCALAR",
+                "name": "String",
+                "ofType": null
+              }
+            }
+          }
+        ],
+        "description": "Provides a scalar specification URL for specifying the behavior of custom scalar types.",
+        "locations": [
+          "SCALAR"
+        ],
+        "name": "specifiedBy"
       }
     ],
     "mutationType": null,
@@ -1339,6 +1362,18 @@
               "name": "__Type",
               "ofType": null
             }
+          },
+          {
+            "args": [],
+            "deprecationReason": null,
+            "description": null,
+            "isDeprecated": false,
+            "name": "specifiedByURL",
+            "type": {
+              "kind": "SCALAR",
+              "name": "String",
+              "ofType": null
+            }
           }
         ],
         "inputFields": null,
@@ -1408,4 +1443,4 @@
       }
     ]
   }
-}
+}

example/starwars/introspect.json

@@ -70,6 +70,29 @@
           "INLINE_FRAGMENT"
         ],
         "name": "skip"
+      },
+      {
+        "args": [
+          {
+            "defaultValue": null,
+            "description": "The URL should point to a human-readable specification of the data format, serialization, and coercion rules.",
+            "name": "url",
+            "type": {
+              "kind": "NON_NULL",
+              "name": null,
+              "ofType": {
+                "kind": "SCALAR",
+                "name": "String",
+                "ofType": null
+              }
+            }
+          }
+        ],
+        "description": "Provides a scalar specification URL for specifying the behavior of custom scalar types.",
+        "locations": [
+          "SCALAR"
+        ],
+        "name": "specifiedBy"
       }
     ],
     "mutationType": {
@@ -1981,6 +2004,18 @@
               "name": "__Type",
               "ofType": null
             }
+          },
+          {
+            "args": [],
+            "deprecationReason": null,
+            "description": null,
+            "isDeprecated": false,
+            "name": "specifiedByURL",
+            "type": {
+              "kind": "SCALAR",
+              "name": "String",
+              "ofType": null
+            }
           }
         ],
         "inputFields": null,
@@ -2050,4 +2085,4 @@
       }
     ]
   }
-}
+}

graphql_test.go

@@ -626,7 +626,7 @@ func TestEmbeddedStruct(t *testing.T) {
 				type Query {
 					course: Course!
 				}
-				
+
 				type Course {
 					name: String!
 					createdAt: String!
@@ -1494,6 +1494,40 @@ func TestDeprecatedDirective(t *testing.T) {
 	})
 }
 
+func TestSpecifiedByDirective(t *testing.T) {
+	gqltesting.RunTests(t, []*gqltesting.Test{
+		{
+			Schema: graphql.MustParseSchema(`
+			schema {
+				query: Query
+			}
+			type Query {
+			}
+			scalar UUID @specifiedBy(
+				url: "https://tools.ietf.org/html/rfc4122"
+			)
+			`, &struct{}{}),
+			Query: `
+				query {
+					__type(name: "UUID") {
+						name
+						specifiedByURL
+					}
+				}
+			`,
+			Variables: map[string]interface{}{},
+			ExpectedResult: `
+				{
+					"__type": {
+						"name": "UUID",
+						"specifiedByURL": "https://tools.ietf.org/html/rfc4122"
+					}
+				}
+			`,
+		},
+	})
+}
+
 type testBadEnumResolver struct{}
 
 func (r *testBadEnumResolver) Hero() *testBadEnumCharacterResolver {
@@ -1854,11 +1888,11 @@ func TestTypeName(t *testing.T) {
 						}
 					}
 				}
-				
+
 				fragment Droid on Droid {
 					name
 					__typename
-				}			  
+				}
 			`,
 			RawResponse:    true,
 			ExpectedResult: `{"hero":{"__typename":"Droid","name":"R2-D2"}}`,
@@ -2478,6 +2512,26 @@ func TestIntrospection(t *testing.T) {
 											}
 										}
 									]
+								},
+								{
+									"name": "specifiedBy",
+									"description": "Provides a scalar specification URL for specifying the behavior of custom scalar types.",
+									"locations": [
+										"SCALAR"
+									],
+									"args": [
+										{
+											"name": "url",
+											"description": "The URL should point to a human-readable specification of the data format, serialization, and coercion rules.",
+											"type": {
+												"kind": "NON_NULL",
+												"ofType": {
+													"kind": "SCALAR",
+													"name": "String"
+												}
+											}
+										}
+									]
 								}
 							]
 						}
@@ -3800,7 +3854,7 @@ func TestPanicAmbiguity(t *testing.T) {
 			name: String!
 			university: University!
 		}
-		
+
 		type University {
 			name: String!
 		}
@@ -4300,11 +4354,11 @@ func TestQueryVariablesValidation(t *testing.T) {
 			  	required: String!
 			  	optional: String
 			}
-			
+
 			type SearchResults {
 				match: String
 			}
-			
+
 			type Query {
 				search(filter: SearchFilter!): [SearchResults!]!
 			}`, &queryVarResolver{}, graphql.UseFieldResolvers()),
@@ -4325,11 +4379,11 @@ func TestQueryVariablesValidation(t *testing.T) {
 				required: String!
 				optional: String
 			}
-			
+
 			type SearchResults {
 				match: String
 			}
-			
+
 			type Query {
 				search(filter: SearchFilter!): [SearchResults!]!
 			}`, &queryVarResolver{}, graphql.UseFieldResolvers()),

internal/schema/meta.go

@@ -59,6 +59,12 @@ var metaSrc = `
 		reason: String = "No longer supported"
 	) on FIELD_DEFINITION | ENUM_VALUE
 
+	# Provides a scalar specification URL for specifying the behavior of custom scalar types.
+	directive @specifiedBy(
+		# The URL should point to a human-readable specification of the data format, serialization, and coercion rules.
+		url: String!
+	) on SCALAR
+
 	# A Directive provides a way to describe alternate runtime execution and type validation behavior in a GraphQL document.
 	#
 	# In some cases, you need to provide options to alter GraphQL's execution behavior
@@ -179,6 +185,7 @@ var metaSrc = `
 		enumValues(includeDeprecated: Boolean = false): [__EnumValue!]
 		inputFields: [__InputValue!]
 		ofType: __Type
+		specifiedByURL: String
 	}
 
 	# An enum describing what kind of type a given ` + "`" + `__Type` + "`" + ` is.

introspection/introspection.go

@@ -189,6 +189,20 @@ func (r *Type) OfType() *Type {
 	}
 }
 
+func (r *Type) SpecifiedByURL() *string {
+	switch t := r.typ.(type) {
+	case *types.ScalarTypeDefinition:
+		if d := t.Directives.Get("specifiedBy"); d != nil {
+			arg := d.Arguments.MustGet("url")
+			url := arg.Deserialize(nil).(string)
+			return &url
+		}
+	default:
+		return nil
+	}
+	return nil
+}
+
 type Field struct {
 	field *types.FieldDefinition
 }