Issue
good day! I don't understand where my problem. Code in Angular 13 On Form have a Button with submit() procedure
export class RegisterComponent implements OnInit {
users: User[] = []
constructor(
public auth: AuthService
) { }
submit() {
this.auth.getByNickName(this.form.value.nickname.trim()).subscribe(
res => {
this.users = res
}
)
}
}
in AuthService
getByNickName(nickname: string): Observable<User[]> {
return this.http.get<User[]>(`${environment.fbDbUrl}/users.json`).pipe(
map((users:User[]) => users.filter((user: User) => user.nickname === nickname))
)
}
Result in console: 6402 ERROR TypeError: users.filter is not a function Why? :-(
Solution
The error that you are mentioning 6402 ERROR TypeError: users.filter is not a function
tells you that users
does not have a method called filter() attached to it.
This is probably because the result of your http.get
method is not an array. For example, it might be an object
, a null
or undefined
value.
As you are fetching a .json
, is suspect it is an object, not an array (It would have been helpful to have a snippet of that file)
To avoid this error you could either:
- use the optional chaining operator (?.) that will prevent calling the filter method on
null
orundefined
values:
map((users:User[]) => users?.filter((user: User) => user.nickname === nickname))
- check if your value is an array with the Array.isArray() method.
To solve your issue, as i don't know how what users.json
file looks like it is hard to help but assuming it is like:
{
"users": [
{
"id": 1,
"name": "User1"
},
{
"id": 2,
"name": "User2"
}
]
}
You would have to modify your map
method to reach the users
property like this :
map((response: { users: User[] }) => response.users.filter((user: User) => user.nickname === nickname))
Answered By - J. Bosi
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