Fix type definition of t to infer resolver shape correctly

.vscode/settings.json

@@ -1,14 +1,9 @@
 {
   "typescript.tsdk": "node_modules/typescript/lib",
-  "typescript.format.enable": false,
-  "[typescript]": {
-    "editor.defaultFormatter": "esbenp.prettier-vscode"
-  },
-  "editor.formatOnSave": true,
   "importSorter.generalConfiguration.sortOnBeforeSave": true,
   "importSorter.importStringConfiguration.hasSemicolon": false,
   "importSorter.importStringConfiguration.maximumNumberOfImportExpressionsPerLine.type": "newLineEachExpressionAfterCountLimitExceptIfOnlyOne",
   "importSorter.importStringConfiguration.maximumNumberOfImportExpressionsPerLine.count": 80,
   "importSorter.importStringConfiguration.tabSize": 2,
   "importSorter.importStringConfiguration.quoteMark": "single"
-}
+}

package.json

@@ -30,6 +30,7 @@
   "dependencies": {
     "dataloader": "^2.0.0",
     "graphql": "^14.5.8",
+    "graphql-middleware": "^4.0.2",
     "memcached": "^2.2.2"
   },
   "devDependencies": {
@@ -39,10 +40,8 @@
     "@nexus/schema": "^0.13.1",
     "@types/memcached": "^2.2.6",
     "apollo-server": "^2.13.1",
-    "graphql-middleware": "^4.0.2",
     "graphql-tools": "^5.0.0",
     "link-module-alias": "^1.2.0",
-    "prettier": "^2.0.5",
     "rimraf": "^3.0.2",
     "tsc-watch": "^4.2.5",
     "typescript": "^3.9.2"

src/examples/with-graphql-tools/index.ts

@@ -1,6 +1,6 @@
 import { ApolloServer } from 'apollo-server'
 import fs from 'fs'
-import { cached } from 'graphql-cached'
+import { cached } from '../../index'
 import { applyMiddleware } from 'graphql-middleware'
 import { makeExecutableSchema } from 'graphql-tools'
 import Memcached from 'memcached'
@@ -34,7 +34,7 @@ const cachedSchema = applyMiddleware(
       Query: {
         user: {
           lifetime: 10,
-          key(_parent: any, args: any) {
+          key(parent, args) {
             return JSON.stringify(args)
           },
         },

src/examples/with-nexus/index.ts

@@ -1,5 +1,5 @@
 import { ApolloServer } from 'apollo-server'
-import { cached } from 'graphql-cached'
+import { cached } from '../../index'
 import { applyMiddleware } from 'graphql-middleware'
 import Memcached from 'memcached'
 import path from 'path'
@@ -46,16 +46,20 @@ const cachedSchema = applyMiddleware(
   cached<Context, ResolversFromNexusGenFieldTypes<NexusGenFieldTypes>>(
     {
       Query: {
+        // @ts-ignore
         user: {
           lifetime: 10,
-          key(_parent: any, args: any) {
+          // @ts-ignore
+          key(_parent, args) {
             return JSON.stringify(args)
           },
         },
       },
       User: {
+        // @ts-ignore
         image: {
           lifetime: 1,
+          // @ts-ignore
           key(parent) {
             return parent.imageId
           },

src/index.ts

@@ -2,16 +2,15 @@ import DataLoader from 'dataloader'
 import { GraphQLResolveInfo } from 'graphql'
 import { promisify } from 'util'
 
-import { CacheField, Config, ResolversBase, T } from './types'
+import type { Config, T, ResolverLike, CacheField } from './types'
+import type { IMiddlewareTypeMap } from 'graphql-middleware'
 
 const DEFAULT_LIFETIME = 10
 
-export function cached<Context, Resolvers = ResolversBase>(
-  t: T<Required<Resolvers>>,
+export function cached<Context, Resolvers>(
+  t: T<Resolvers>,
   config: Config<Context>
-) {
-  const _t: any = t
-
+): IMiddlewareTypeMap<any, Context> {
   /**
    * Initialize cache getter(loader), setter
    */
@@ -28,17 +27,19 @@ export function cached<Context, Resolvers = ResolversBase>(
     }
   )
 
-  const resolveWithCache = async (
-    resolve: any,
-    parent: any,
-    args: any,
+  const resolveWithCache = async<Type, Parent, Arg>(
+    resolve: ResolverLike<Type, Parent, Arg, Context>,
+    parent: Parent,
+    args: Arg,
     context: Context,
     info: GraphQLResolveInfo
-  ) => {
-    const _typeName = info.parentType.toString()
-    const _fieldName = info.fieldName
+  ): Promise<Type> => {
+    const _typeName = info.parentType.toString() as keyof typeof t;
+    const _type = t[_typeName];
+
+    const _fieldName = info.fieldName as keyof typeof _type;
+    const _field = _type[_fieldName] as CacheField<Type, Parent, Arg, Context>;
 
-    const _field: CacheField<any, any, any> = _t[_typeName][_fieldName]
     const _fieldKey = 'key' in _field ? _field.key : _field
     const _fieldSerializer = 'serializer' in _field ? _field.serializer : null
     const _fieldLifetime = 'lifetime' in _field ? _field.lifetime : null
@@ -64,7 +65,7 @@ export function cached<Context, Resolvers = ResolversBase>(
      * Get cache from cache storage
      */
     config.beforeGet?.(key, null)
-    const cachedItem = (await cacheLoader.load(key)) || null
+    const cachedItem = (await cacheLoader.load(key) as unknown as Type) || null
     config.afterGet?.(key, cachedItem)
 
     if (cachedItem) {
@@ -104,12 +105,16 @@ export function cached<Context, Resolvers = ResolversBase>(
     }
   }
 
-  const resolvers: any = {}
+  const resolvers: any = {};
 
-  for (const typeName of Object.keys(_t)) {
-    resolvers[typeName] = {}
+  for (const typeName of Object.keys(t)) {
+    resolvers[typeName] = {};
 
-    for (const fieldName of Object.keys(_t[typeName])) {
+    const _type = t[typeName as keyof typeof t];
+    if (!_type) {
+      continue;
+    }
+    for (const fieldName of Object.keys(_type as NonNullable<typeof _type>)) {
       resolvers[typeName][fieldName] = resolveWithCache
     }
   }

src/types/resolvers.ts

@@ -1,9 +1,8 @@
-export interface ResolversBase {
-  [typeName: string]:
-    | {
-        [fieldName: string]:
-          | ((parent: any, args: any, context: any, info: any) => any)
-          | undefined
-      }
-    | undefined
-}
+import type { GraphQLResolveInfo } from "graphql";
+
+export type ResolverLike<Type, Parent, Arg, Context = any> = (
+  root: Parent,
+  args: Arg,
+  context: Context,
+  info: GraphQLResolveInfo
+) => Type | Promise<Type>;

src/types/t.ts

@@ -1,57 +1,50 @@
-import { GraphQLResolveInfo } from 'graphql'
+import type { ResolverLike } from "./resolvers";
 
-export type T<RequiredResolvers> = {
-  [TypeName in keyof RequiredResolvers]?: {
-    [FieldName in keyof RequiredResolvers[TypeName]]?: CacheField<
-      Parameters<RequiredResolvers[TypeName][FieldName]>[0],
-      Parameters<RequiredResolvers[TypeName][FieldName]>[1],
-      Parameters<RequiredResolvers[TypeName][FieldName]>[2]
-    >
-  }
-}
+export type T<Resolvers> = (
+  Resolvers extends { [key: string]: infer _ }
+  ? { [P in keyof Resolvers]?: T<Resolvers[P]> }
+  : Resolvers extends ResolverLike<infer Type, infer Parent, infer Arg, infer Context>
+  ? CacheField<Type, Parent, Arg, Context>
+  : never
+);
 
-export type CacheField<Parent, Arg, Context> =
+export type CacheField<Type, Parent, Arg, Context> = (
   | CacheFieldKey<Parent, Arg, Context>
   | {
-      /**
+    /**
        * Create a cache key by combining parent, args, context and info.
        * @param {Object} parent
        * @param {Object} args
        * @param {Object} context
        * @param {Object} info
        */
-      key: CacheFieldKey<Parent, Arg, Context>
+    key: CacheFieldKey<Parent, Arg, Context>;
 
-      /**
+    /**
        * How much time to keep the cache (seconds)
        */
-      lifetime?: number
+    lifetime?: number;
 
-      /**
+    /**
        * Preprocess item before storing in cache and after fetching from cache
        */
-      serializer?: CacheFieldSerializer
-    }
-
-export type CacheFieldKey<Parent, Arg, Context> = (
-  parent: Parent,
-  args: Arg,
-  context: Context,
-  info: GraphQLResolveInfo
-) => string
+    serializer?: CacheFieldSerializer<Type>;
+  }
+);
 
-export type CacheFieldSerializer = {
+export type CacheFieldKey<Parent, Arg, Context> = ResolverLike<string, Parent, Arg, Context>;
+export type CacheFieldSerializer<Type> = {
   /**
    * Preprocess item before storing it in the cache
    * @param {Object} item
    * @returns {Object} Serialized item
    */
-  serialize(item: any): any
+  serialize(item: Type): any;
 
   /**
    * Preprocess item after fetching from cache
    * @param {Object} Serialized item
    * @returns {Object} Item
    */
-  deserialize(serializedItem: any): any
-}
+  deserialize(serializedItem: any): Type;
+};

yarn.lock

@@ -3959,11 +3959,6 @@ posix-character-classes@^0.1.0:
   resolved "https://registry.yarnpkg.com/posix-character-classes/-/posix-character-classes-0.1.1.tgz#01eac0fe3b5af71a2a6c02feabb8c1fef7e00eab"
   integrity sha1-AerA/jta9xoqbAL+q7jB/vfgDqs=
 
-prettier@^2.0.5:
-  version "2.0.5"
-  resolved "https://registry.yarnpkg.com/prettier/-/prettier-2.0.5.tgz#d6d56282455243f2f92cc1716692c08aa31522d4"
-  integrity sha512-7PtVymN48hGcO4fGjybyBSIWDsLU4H4XlvOHfq91pz9kkGlonzwTfYkaIEwiRg/dAJF9YlbsduBAgtYLi+8cFg==
-
 prisma-json-schema@0.1.3:
   version "0.1.3"
   resolved "https://registry.yarnpkg.com/prisma-json-schema/-/prisma-json-schema-0.1.3.tgz#6c302db8f464f8b92e8694d3f7dd3f41ac9afcbe"