feat: initial commit

Signed-off-by: Chris Lahaye <mail@chrislahaye.com>

.eslintrc

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+{
+  "root": true,
+  "parser": "@typescript-eslint/parser",
+  "plugins": [
+    "@typescript-eslint"
+  ],
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/eslint-recommended",
+    "plugin:@typescript-eslint/recommended"
+  ],
+  "rules": {
+    "@typescript-eslint/no-explicit-any": [0],
+    "no-prototype-builtins": [0]
+  }
+}

.gitignore

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+lib/**/*.d.ts
+lib/**/*.js
+node_modules

README.md

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+# type-graphql-utils
+[![npm version](https://img.shields.io/npm/v/type-graphql-utils)](https://www.npmjs.com/package/type-graphql-utils)
+[![npm downloads](https://img.shields.io/npm/dm/type-graphql-utils.svg)](https://www.npmjs.com/package/type-graphql-utils)
+[![Known Vulnerabilities](https://snyk.io/test/github/chrislahaye/type-graphql-utils/badge.svg)](https://snyk.io/test/github/chrislahaye/type-graphql-utils)
+
+This module provides utilities to transform [type-graphql](https://www.npmjs.com/package/type-graphql) types.
+
+## Install
+
+```shell
+yarn install type-graphql-utils
+```
+
+## Usage
+
+```ts
+import { Field, InputType, ObjectType } from 'type-graphql';
+import { Pick, Partial } from 'type-graphql-utils';
+
+@ObjectType()
+class User {
+  @Field()
+  id!: number;
+
+  @Field()
+  name!: string;
+
+  @Field()
+  email!: string;
+}
+```
+
+```
+type User {
+  id: String!
+  name: String!
+  email: String!
+}
+```
+
+```ts
+@InputType()
+class UserInput1 extends Partial(User) {
+  // extra fields
+}
+```
+
+```
+input UserInput1 {
+  id: String
+  name: String
+  email: String
+}
+```
+
+```ts
+@InputType()
+class UserInput2 extends Pick(User, { name: 1 }) { }
+```
+
+```
+input UserInput2 {
+  name: String!
+}
+```
+
+```ts
+@InputType()
+class UserInput3 extends Required(Partial(User), { id: 1 }) {}
+```
+
+```
+input UserInput3 {
+  id: String!
+  name: String
+  email: String
+}
+```
+
+## API
+
+**`BaseClass`**: The type to transform. A class decorated with `@InputType()` or `@ObjectType()`.
+
+**`names`**: The fields to transform. A potentially optional object containing the names of the fields as key, e.g. `{ id: 1, name: 1 }`. The TypeScript type enforces all values to be *1*, but the value isn't actually used. We just need the names as object to determine if a name is included in constant time.
+
+### `Pick(BaseClass, names)`
+
+Constructs a type by picking the keys of `names` from `BaseClass`.
+
+### `Omit(BaseClass, names)`
+
+Constructs a type by picking all fields from `BaseClass` and then removing the keys of `names`.
+
+### `Partial(BaseClass, [names])`
+
+Constructs a type by picking all fields from `BaseClass` and then setting the keys of `names` to optional. The opposite of Required. By default, `names` contains all names.
+
+### `Required(BaseClass, [names])`
+
+Constructs a type by picking all fields from `BaseClass` and then setting the keys of `names` to required. The opposite of Partial. By default, `names` contains all names.

lib/index.ts

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+import { ClassType, getMetadataStorage, InputType, registerEnumType, ObjectType } from 'type-graphql';
+import type { FieldMetadata } from 'type-graphql/dist/metadata/definitions';
+
+type PartialBy<T, K extends keyof T> = Omit<T, K> & Partial<Pick<T, K>>;
+type RequiredBy<T, K extends keyof T> = Omit<T, K> & Required<Pick<T, K>>;
+
+const metadata = getMetadataStorage();
+
+export function buildEnum<T extends ClassType>(
+  Class: T,
+  name: string,
+): Record<keyof InstanceType<T>, keyof InstanceType<T>> {
+  const enumObj = {} as Record<keyof InstanceType<T>, keyof InstanceType<T>>;
+
+  metadata.fields.forEach((f) => {
+    if (f.target !== Class && !f.target.isPrototypeOf(Class)) return;
+
+    enumObj[f.name as keyof InstanceType<T>] = f.name;
+  });
+
+  registerEnumType(enumObj, { name });
+
+  return enumObj;
+}
+
+export function buildType(
+  BaseClass: ClassType,
+  buildFn: (f: FieldMetadata) => FieldMetadata | FieldMetadata[] | undefined,
+): any {
+  @InputType({ isAbstract: true })
+  @ObjectType({ isAbstract: true })
+  class ChildClass { }
+
+  metadata.fields.forEach((f) => {
+    if (f.target !== BaseClass && !f.target.isPrototypeOf(BaseClass)) return;
+
+    const field = buildFn(f);
+
+    if (field instanceof Array) {
+      field.forEach((field) =>
+        metadata.fields.push({ ...field, target: ChildClass })
+      );
+    } else if (field) {
+      metadata.fields.push({ ...field, target: ChildClass })
+    }
+  });
+
+  return ChildClass;
+}
+
+export function Pick<T extends ClassType, K extends keyof InstanceType<T>>(BaseClass: T, names: Record<K, 1>): ClassType<Pick<InstanceType<T>, K>> {
+  return buildType(BaseClass, (f) => f.name in names ? f : undefined);
+}
+
+export function Omit<T extends ClassType, K extends keyof InstanceType<T>>(BaseClass: T, names: Record<K, 1>): ClassType<Omit<InstanceType<T>, K>> {
+  return buildType(BaseClass, (f) => f.name in names ? undefined : f);
+}
+
+export function Partial<T extends ClassType, K extends keyof InstanceType<T> = keyof InstanceType<T>>(BaseClass: T, names?: Record<K, 1>): ClassType<PartialBy<InstanceType<T>, K>> {
+  return buildType(BaseClass, (f) => !names || f.name in names ? { ...f, typeOptions: { ...f.typeOptions, nullable: true } } : f);
+}
+
+export function Required<T extends ClassType, K extends keyof InstanceType<T> = keyof InstanceType<T>>(BaseClass: T, names?: Record<K, 1>): ClassType<RequiredBy<InstanceType<T>, K>> {
+  return buildType(BaseClass, (f) => !names || f.name in names ? { ...f, typeOptions: { ...f.typeOptions, nullable: false } } : f);
+}

package.json

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+{
+  "name": "type-graphql-utils",
+  "version": "1.0.0",
+  "description": "utilities to transform type-graphql types",
+  "main": "lib/index.js",
+  "types": "lib/index.d.ts",
+  "files": [
+    "lib/**/*"
+  ],
+  "scripts": {
+    "prepare": "install-peers && tsc",
+    "build": "tsc",
+    "watch": "tsc -w"
+  },
+  "repository": {
+    "type": "git",
+    "url": "github:ChrisLahaye/type-graphql-utils"
+  },
+  "keywords": [
+    "type-graphql"
+  ],
+  "author": "Chris Lahaye <mail@chrislahaye.com>",
+  "license": "MIT",
+  "bugs": {
+    "url": "https://github.com/ChrisLahaye/type-graphql-utils/issues"
+  },
+  "devDependencies": {
+    "@typescript-eslint/eslint-plugin": "^5.32.0",
+    "@typescript-eslint/parser": "^5.32.0",
+    "eslint": "^8.21.0",
+    "install-peers-cli": "^2.2.0",
+    "typescript": "^4.7.4"
+  },
+  "peerDependencies": {
+    "graphql": "^15",
+    "type-graphql": "^1"
+  }
+}

tsconfig.json

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+{
+  "compilerOptions": {
+    "declaration": true,
+    "lib": ["ES2020"],
+    "module": "commonjs",
+    "target": "ES2020",
+    "skipLibCheck": true,
+    "strict": true,
+    "experimentalDecorators": true
+  }
+}