Add support for custom enum resolvers and scalar types

CHANGELOG.md

@@ -18,7 +18,7 @@
 - `apollo-env`
   - <First `apollo-env` related entry goes here>
 - `apollo-graphql`
-  - <First `apollo-graphql` related entry goes here>
+  - buildSchemaFromSDL - Add support for merging Scalar and Enum resolvers to schema [#1345](https://github.com/apollographql/apollo-tooling/pull/1345)
 - `apollo-language-server`
   - <First `apollo-language-server` related entry goes here>
 - `apollo-tools`

packages/apollo-graphql/src/schema/__tests__/buildSchemaFromSDL.test.ts

@@ -5,7 +5,13 @@ import {
   GraphQLDirective,
   DirectiveLocation,
   GraphQLObjectType,
-  GraphQLAbstractType
+  GraphQLAbstractType,
+  GraphQLScalarType,
+  GraphQLScalarTypeConfig,
+  GraphQLEnumType,
+  Kind,
+  execute,
+  ExecutionResult
 } from "graphql";
 
 import astSerializer from "./snapshotSerializers/astSerializer";
@@ -422,5 +428,80 @@ type MutationRoot {
       expect(animalUnion.resolveType).toBe(resolveTypeUnion);
       expect(creatureInterface.resolveType).toBe(resolveTypeInterface);
     });
+
+    it(`should add resolvers for scalar types`, () => {
+      const typeDefs = gql`
+        scalar Custom
+      `;
+
+      const customTypeConfig: GraphQLScalarTypeConfig<string, string> = {
+        name: "Custom",
+        serialize: value => value,
+        parseValue: value => value,
+        parseLiteral: input => {
+          if (input.kind !== Kind.STRING) {
+            throw new Error("Expected value to be string");
+          }
+          return input.value;
+        }
+      };
+
+      const CustomType = new GraphQLScalarType(customTypeConfig);
+
+      const resolvers = { Custom: CustomType };
+
+      const schema = buildSchemaFromSDL([{ typeDefs, resolvers }]);
+      const custom = schema.getType("Custom") as GraphQLScalarType;
+
+      expect(custom.parseLiteral).toBe(CustomType.parseLiteral);
+      expect(custom.parseValue).toBe(CustomType.parseValue);
+      expect(custom.serialize).toBe(CustomType.serialize);
+    });
+
+    it(`should add resolvers to enum types`, () => {
+      const typeDefs = gql`
+        enum AllowedColor {
+          RED
+          GREEN
+          BLUE
+        }
+
+        type Query {
+          favoriteColor: AllowedColor
+          avatar(borderColor: AllowedColor): String
+        }
+      `;
+
+      const mockResolver = jest.fn();
+
+      const resolvers = {
+        AllowedColor: {
+          RED: "#f00",
+          GREEN: "#0f0",
+          BLUE: "#00f"
+        },
+        Query: {
+          favoriteColor: () => "#f00",
+          avatar: (_: any, params: any) => mockResolver(_, params)
+        }
+      };
+
+      const schema = buildSchemaFromSDL([{ typeDefs, resolvers }]);
+      const colorEnum = schema.getType("AllowedColor") as GraphQLEnumType;
+
+      let result = execute(
+        schema,
+        gql`
+          query {
+            favoriteColor
+            avatar(borderColor: RED)
+          }
+        `
+      );
+
+      expect((result as ExecutionResult).data!.favoriteColor).toBe("RED");
+      expect(colorEnum.getValue("RED")!.value).toBe("#f00");
+      expect(mockResolver).toBeCalledWith(undefined, { borderColor: "#f00" });
+    });
   });
 });

packages/apollo-graphql/src/schema/buildSchemaFromSDL.ts

@@ -14,7 +14,11 @@ import {
   SchemaExtensionNode,
   OperationTypeNode,
   GraphQLObjectType,
-  isAbstractType
+  GraphQLEnumType,
+  isAbstractType,
+  isScalarType,
+  isEnumType,
+  GraphQLEnumValue
 } from "graphql";
 import { validateSDL } from "graphql/validation/validate";
 import { isDocumentNode, isNode } from "../utilities/graphql";
@@ -216,6 +220,39 @@ export function addResolversToSchema(
       }
     }
 
+    if (isScalarType(type)) {
+      for (const fn in fieldConfigs) {
+        (type as any)[fn] = (fieldConfigs as any)[fn];
+      }
+    }
+
+    if (isEnumType(type)) {
+      const values = type.getValues();
+      const newValues: { [key: string]: GraphQLEnumValue } = {};
+      values.forEach(value => {
+        const newValue = (fieldConfigs as any)[value.name] || value.name;
+        newValues[value.name] = {
+          value: newValue,
+          deprecationReason: value.deprecationReason,
+          description: value.description,
+          astNode: value.astNode,
+          name: value.name
+        };
+      });
+
+      // In place updating hack to get around pulling in the full
+      // schema walking and immutable updating machinery from graphql-tools
+      Object.assign(
+        type,
+        new GraphQLEnumType({
+          name: type.name,
+          description: type.description,
+          astNode: type.astNode,
+          values: newValues
+        })
+      );
+    }
+
     if (!isObjectType(type)) continue;
 
     const fieldMap = type.getFields();

packages/apollo-graphql/src/schema/resolverMap.ts

@@ -1,12 +1,17 @@
-import { GraphQLFieldResolver } from "graphql";
+import { GraphQLFieldResolver, GraphQLScalarType } from "graphql";
 
 export interface GraphQLResolverMap<TContext = {}> {
-  [typeName: string]: {
-    [fieldName: string]:
-      | GraphQLFieldResolver<any, TContext>
-      | {
-          requires?: string;
-          resolve: GraphQLFieldResolver<any, TContext>;
-        };
-  };
+  [typeName: string]:
+    | {
+        [fieldName: string]:
+          | GraphQLFieldResolver<any, TContext>
+          | {
+              requires?: string;
+              resolve: GraphQLFieldResolver<any, TContext>;
+            };
+      }
+    | GraphQLScalarType
+    | {
+        [enumValue: string]: string | number;
+      };
 }