Add createFilterProps

packages/common/src/filterProps.test.ts

@@ -0,0 +1,35 @@
+import {createFilterProps} from './filterProps'
+
+interface IEntity {
+  readonly id: number
+}
+
+interface IPerson {
+  readonly firstName: string
+  readonly lastName: string
+}
+
+interface IPersonEntity extends IEntity, IPerson {}
+
+describe('filterProps', () => {
+
+  const p: IPersonEntity = {
+    id: 1,
+    firstName: 'John',
+    lastName: 'Smith',
+  }
+
+  const filterProps = createFilterProps<IPerson>({
+    firstName: true,
+    lastName: true,
+  })
+
+  it('picks only relevant props', () => {
+    const person = filterProps(p)
+    expect(person).toEqual({
+      firstName: 'John',
+      lastName: 'Smith',
+    })
+  })
+
+})

packages/common/src/filterProps.ts

@@ -0,0 +1,8 @@
+export function createFilterProps<T>(schema: Record<keyof T & string, true>) {
+  return function filterProps<U extends T>(item: U): T {
+    return Object.keys(schema).reduce((obj: T, key) => {
+      obj[key as keyof T] = item[key as keyof T]
+      return obj
+    }, {} as T)
+  }
+}

packages/common/src/index.ts

@@ -10,6 +10,7 @@ export * from './IUser'
 export * from './IUserInTeam'
 export * from './IUserTeam'
 export * from './URLFormatter'
+export * from './filterProps'
 export * from './indexBy'
 export * from './types'
 export * from './without'