Merge pull request #64 from shiftcode/#62-add-object-utilities

#62 add object utilities

Author: mumenthalers

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "@shiftcode/logger",
-  "version": "3.0.1",
+  "version": "3.0.2-pr62.0",
   "description": "logger for local and aws lambda execution",
   "repository": "https://github.com/shiftcode/sc-commons-public",
   "license": "UNLICENSED",
@@ -37,7 +37,7 @@
     "test:watch": "npm run test -- --watch"
   },
   "devDependencies": {
-    "@shiftcode/utilities": "^4.1.0"
+    "@shiftcode/utilities": "^4.2.0-pr62.0"
   },
   "peerDependencies": {
     "@shiftcode/utilities": "^4.0.0 || ^4.0.0-pr53"

packages/logger/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@shiftcode/utilities",
-  "version": "4.1.0",
+  "version": "4.2.0-pr62.0",
   "description": "Contains some utilities",
   "repository": "https://github.com/shiftcode/sc-commons-public",
   "license": "MIT",

packages/utilities/package.json

@@ -7,8 +7,10 @@ export * from './lib/group-by/group-by.js'
 export * from './lib/http/http-constants.js'
 export * from './lib/json-stringify-replacer/json-stringify-replacer.function.js'
 export * from './lib/map-values-deep/map-values-deep.js'
+export * from './lib/object/get-value-assert-defined.function.js'
 export * from './lib/object/omit-props.function.js'
 export * from './lib/object/pick-props.function.js'
+export * from './lib/object/pick-props-assert-defined.function.js'
 export * from './lib/promise/make-deferred.function.js'
 export * from './lib/math/clamp.function.js'
 export * from './lib/math/random-int.js'

packages/utilities/src/index.ts

@@ -0,0 +1,50 @@
+import { getValueAssertDefined } from './get-value-assert-defined.function.js'
+
+describe('getValueAssertDefined', () => {
+  interface Test {
+    x: string | null
+    y?: boolean
+    z: number | undefined
+  }
+
+  describe('throws when not defined', () => {
+    const empty: Test = { x: null, z: undefined }
+
+    test('when null', () => {
+      expect(() => getValueAssertDefined(empty, 'x')).toThrow()
+    })
+
+    test('when undefined', () => {
+      expect(() => getValueAssertDefined(empty, 'z')).toThrow()
+    })
+
+    test('when optional', () => {
+      expect(() => getValueAssertDefined(empty, 'y')).toThrow()
+    })
+  })
+
+  describe('returns value when defined', () => {
+    const obj: Test = {
+      x: '',
+      y: false,
+      z: 0,
+    }
+
+    test('when empty string', () => {
+      expect(getValueAssertDefined(obj, 'x')).toEqual('')
+    })
+    test('when false', () => {
+      expect(getValueAssertDefined(obj, 'y')).toEqual(false)
+    })
+    test('when zero', () => {
+      expect(getValueAssertDefined(obj, 'z')).toEqual(0)
+    })
+
+    test('makes it type safe', () => {
+      const tDefined: { num: number | null } = { num: 42 }
+      // assign to variable to ensure type safety
+      const res: number = getValueAssertDefined(tDefined, 'num')
+      expect(res).toEqual(42)
+    })
+  })
+})

packages/utilities/src/lib/object/get-value-assert-defined.function.spec.ts

@@ -0,0 +1,14 @@
+import { isDefined } from '../ts-guards/is-defined.js'
+
+/**
+ * returns the value of the provided key on given object. throws if the value is null or undefined
+ */
+export function getValueAssertDefined<T, K extends keyof T>(obj: T, key: K): NonNullable<T[K]> {
+  type X = NonNullable<T[K]>
+  const value: X | null | undefined = <any>obj[key]
+
+  if (!isDefined(value)) {
+    throw new Error(`Expected property "${String(key)}" to be defined. Was "${value}" instead`)
+  }
+  return value
+}

packages/utilities/src/lib/object/get-value-assert-defined.function.ts

@@ -0,0 +1,12 @@
+import { pickPropsAssertDefined } from './pick-props-assert-defined.function.js'
+
+describe('pickPropsAssertDefined', () => {
+  test('returns object with picked props', () => {
+    const obj = { a: true, b: 'foo', c: 42 }
+    expect(pickPropsAssertDefined(obj, ['a', 'c'])).toEqual({ a: true, c: 42 })
+  })
+  test('throws when picked prop values are null or undefined', () => {
+    const obj = { a: 'ok', b: null }
+    expect(() => pickPropsAssertDefined(obj, ['a', 'b'])).toThrow(Error)
+  })
+})

packages/utilities/src/lib/object/pick-props-assert-defined.function.spec.ts

@@ -0,0 +1,21 @@
+import { isDefined } from '../ts-guards/is-defined.js'
+
+export type PickedPropsDefined<T, K extends keyof T> = {
+  [key in K]-?: NonNullable<T[key]>
+}
+
+/**
+ * returns an object containing the provided props with their respective value. throws if their value is null or undefined
+ */
+export function pickPropsAssertDefined<T, TProp extends keyof T>(
+  obj: T,
+  props: readonly TProp[],
+): PickedPropsDefined<T, TProp> {
+  const entries = props.map((p) => {
+    if (!isDefined(obj[p])) {
+      throw new Error(`Expected property "${String(p)}" to be defined. Was "${String(obj[p])}" instead`)
+    }
+    return [p, obj[p]]
+  })
+  return Object.fromEntries(entries)
+}