template_0205

RN_TEMPLATE/app/utils/storage/index.ts

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+import { MMKV } from "react-native-mmkv"
+
+export const storage = new MMKV()
+
+/**
+ * Loads a string from storage.
+ *
+ * @param key The key to fetch.
+ */
+export function loadString(key: string): string | null {
+  try {
+    return storage.getString(key) ?? null
+  } catch {
+    // not sure why this would fail... even reading the RN docs I'm unclear
+    return null
+  }
+}
+
+/**
+ * Saves a string to storage.
+ *
+ * @param key The key to fetch.
+ * @param value The value to store.
+ */
+export function saveString(key: string, value: string): boolean {
+  try {
+    storage.set(key, value)
+    return true
+  } catch {
+    return false
+  }
+}
+
+/**
+ * Loads something from storage and runs it thru JSON.parse.
+ *
+ * @param key The key to fetch.
+ */
+export function load<T>(key: string): T | null {
+  let almostThere: string | null = null
+  try {
+    almostThere = loadString(key)
+    return JSON.parse(almostThere ?? "") as T
+  } catch {
+    return (almostThere as T) ?? null
+  }
+}
+
+/**
+ * Saves an object to storage.
+ *
+ * @param key The key to fetch.
+ * @param value The value to store.
+ */
+export function save(key: string, value: unknown): boolean {
+  try {
+    saveString(key, JSON.stringify(value))
+    return true
+  } catch {
+    return false
+  }
+}
+
+/**
+ * Removes something from storage.
+ *
+ * @param key The key to kill.
+ */
+export function remove(key: string): void {
+  try {
+    storage.delete(key)
+  } catch {}
+}
+
+/**
+ * Burn it all to the ground.
+ */
+export function clear(): void {
+  try {
+    storage.clearAll()
+  } catch {}
+}

RN_TEMPLATE/app/utils/storage/storage.test.ts

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+import { load, loadString, save, saveString, clear, remove, storage } from "."
+
+const VALUE_OBJECT = { x: 1 }
+const VALUE_STRING = JSON.stringify(VALUE_OBJECT)
+
+describe("MMKV Storage", () => {
+  beforeEach(() => {
+    storage.clearAll()
+    storage.set("string", "string")
+    storage.set("object", JSON.stringify(VALUE_OBJECT))
+  })
+
+  it("should be defined", () => {
+    expect(storage).toBeDefined()
+  })
+
+  it("should have default keys", () => {
+    expect(storage.getAllKeys()).toEqual(["string", "object"])
+  })
+
+  it("should load data", () => {
+    expect(load<object>("object")).toEqual(VALUE_OBJECT)
+    expect(loadString("object")).toEqual(VALUE_STRING)
+
+    expect(load<string>("string")).toEqual("string")
+    expect(loadString("string")).toEqual("string")
+  })
+
+  it("should save strings", () => {
+    saveString("string", "new string")
+    expect(loadString("string")).toEqual("new string")
+  })
+
+  it("should save objects", () => {
+    save("object", { y: 2 })
+    expect(load<object>("object")).toEqual({ y: 2 })
+    save("object", { z: 3, also: true })
+    expect(load<object>("object")).toEqual({ z: 3, also: true })
+  })
+
+  it("should save strings and objects", () => {
+    saveString("object", "new string")
+    expect(loadString("object")).toEqual("new string")
+  })
+
+  it("should remove data", () => {
+    remove("object")
+    expect(load<object>("object")).toBeNull()
+    expect(storage.getAllKeys()).toEqual(["string"])
+
+    remove("string")
+    expect(load<string>("string")).toBeNull()
+    expect(storage.getAllKeys()).toEqual([])
+  })
+
+  it("should clear all data", () => {
+    expect(storage.getAllKeys()).toEqual(["string", "object"])
+    clear()
+    expect(storage.getAllKeys()).toEqual([])
+  })
+})