Added Filter by Role to user search

[SebiWrn]

Motivation and Context

You can now filter users by their role, improves administration and overview over admins.

Steps for Testing

Prerequisites:

• 1 Admin

1. Log in
2. Navigate to User management page
3. View the new Dropdown

Screenshots

[github-actions]

Your Testserver will be ready at https://1278.test.live.mm.rbg.tum.de in a few minutes.

Logins

Kurs1	Kurs2	Kurs3	Kurs4
public	public	loggedin	enrolled
prof1	prof1	prof2	prof1 prof2
student1 student2 student3	student1 student2	student2 student3	student1 student2

[YiranDuan721]

There's a small problem: after filtering, the user's email doesn't seem to be displayed

[karjo24]

Filtering locally results in no show of potential results. Simplest case of this is filtering for students without query string. Change the API instead.

[karjo24]

There's a small problem: after filtering, the user's email doesn't seem to be displayed

I cannot reproduce this problem in Mozilla Firefox for Ubuntu 132.0.2 (64-Bit) or Google Chrome Version 130.0.6723.58 (Official Build) (64-bit).

[joschahenningsen]

Looks great, just added two remarks

[kordianbruck]

all of these variable names are hard to understand without context. Also why are we only enforcing the regex on one of the two paramters? Does rQ not need to be checked for validity?

[kordianbruck]

Edited the PR, PTAL if you think thats better (otherwise revert my commit please).

[karjo24]

Also why are we only enforcing the regex on one of the two paramters? Does rQ not need to be checked for validity?

Probably hard to immediately understand and therefore bad code, but it's checked before it's used:

gocast/api/users.go

Lines 143 to 144 in 6d0c3cc

	role, err := strconv.ParseUint(roleQuery, 10, 64)
	if err != nil {

outdated.