Validate Map object in v6

[thegeett]

Not sure how to validate new Map() object, in your Validation Guide you have demonstrate boolean, string, number, array but not map.
If I have

let map = new Map();
map.set('abc', someArrayObject);
map.set('def', someArrayObject);

this.localStorage.setItem('test', map).subscribe(() => {
console.log('Done MAP');
}, () => {
console.log('Error MAP');
});

SO how could I create schema to validate map object while getItem()?

[cyrilletuzi]

Thanks for your interest for this lib.

The JSON schema standard can only describe JSON, ie. literal objects. So for instances of specific classes, like Map, you'll need to do your own validation, for example:

this.localStorage.getItem(key).subscribe((result) => {
  if (result instanceof Map) {}
});

Beware that in some special cases (private mode for example), the lib will fallback to localStorage, where data will be serialized. But a JavaScript Map is not serializable to JSON. To be exact, seriazalization works (JSON.stringify()), but when unserializing (JSON.parse()), you won't get a real Map.

For now, a safer way to store a Map would be this:

const index = 'map';
const someMap = new Map<string, number>([['test1', 1], ['test2', 2]]);

/* Writing */
this.localStorage.setItem(index, Array.from(someMap)).subscribe();

/* Reading */
this.localStorage.getItem(index).pipe(
  map((data) => new Map(data)),
).subscribe((data) => {
  data.get('test1');
});

Then, you could use a JSON Schema to validate:

const schema: JSONSchema = {
  type: 'array',
  items: {
    type: 'array',
    items: [
      { type: 'string' },
      { type: 'number' },
    ],
  },
};

this.localStorage.getItem<[string, number][]>(index, { schema }).pipe(
  map((data) => new Map(data)),
).subscribe((data) => {
  data.get('test1');
});

I'll add this in v8 documentation, and think if the lib can do something about these cases. Thanks for pointing this out.

[cyrilletuzi]

Edited my answer as it was inexact.

[thegeett]

Thanks it worked!