CODEWITHSUNDEEP
typescript
Richardson
Richardson

Reputation: 2285

filter an array of two different types without the use of casting?

How to filter an array of tow different types and get the targeted type, I used casing but I caused issues further in the code and I cannot use function predicated since I haven't isolated the value yet any idea how to this ?

the error I am getting on el.user is

Property 'user' does not exist on type 'UserType' | 'AdminType'

export type UserType = { user: string; data: string}
export type AdminType = { admin: string; data: string }


const usersAndAdminsArr =[{ admin: '2312'; data: 'blabla' }, { admin: '33123'; data: 'blabla' }, { user: '111'; data: '' }] 
// get the array of filter users only (exclude admins)

const userType = usersAndAdminsArr.filter((el) => el.user === selected.user);

 const isUser = (item: any): item is UserType => {
      return item.user !== undefined;
  };

Upvotes: 0

Views: 97

Answers (1)

ddejohn
ddejohn

Reputation: 8962

You're not actually applying your type guard. You need to first filter out non UserType objects, and then filter the users.

usersAndAdminsArr.filter(isUser).filter((userObj) => userObj.user === selected.user)

See playground and make sure you also take a look at Array.prototype.find()

Upvotes: 1

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