C#•9mo ago

Help making login function c#

Im currently trying to code a login function I have the registration my user is getting saved in the db! So now i want to check the user(I am using Asp.Net Web Api for it) my api is connected to my frontend and like i said the user is being saved in the db. i wrote that method for the login in my api(see picture) and idk how i could bind that in my frontend...

41 Replies

Angius•9mo ago

Well, your method doesn't check anything useful right now So there's that For a "binding"... what do you mean? You call this API endpoint with fetch or axios or whatever And do whatever with the data you get back

kurumi•9mo ago

use ur DbContext or whatever to match user data via DI

IbraDev💻OP•9mo ago

Basically i mean i can post my user and he's getting saved but i can tget it how i could check that he existing i tried severall methods(Pictures of the frontend code)

kurumi•9mo ago

also why are your users provide password hash insted of simply pass? It is better to create new DTO model which represents login request with needed data. And then you can map it to next layer of your logic

Angius•9mo ago

You check that a given user exists and has the correct password by... checking that 1. Get the user by username from the database 2. Hash the provided password with the retrieve'd user's salt 3. Compare the hashes

IbraDev💻OP•9mo ago

i did something else before i forgot to change the name 😦 I dont do something now with hash i changed my program i now just want to have a login and sign up

kurumi•9mo ago

Also, you can try something called Identity https://learn.microsoft.com/en-us/aspnet/core/security/authentication/identity?view=aspnetcore-8.0&tabs=visual-studio it does a lot of magic that usually helps with sign in/up

Angius•9mo ago

Do you not hash the passwords? Do you store them in the database as plain text?

IbraDev💻OP•9mo ago

yeah right. I hashed them before but now i changed the whole program because of that i just want to check my user

Angius•9mo ago

Well, then I hope you don't plan to actually let anybody get even close to this project Because hashing passwords is security 101

IbraDev💻OP•9mo ago

here i just trying to send the user(which works) and to check the user (were i have problems)

Angius•9mo ago

IbraDev💻OP•9mo ago

no its just for educational purposes

Angius•9mo ago

Just... check the user exists?

IbraDev💻OP•9mo ago

yes

Angius•9mo ago

var exists = await _context.Users.AnyAsync(u => u.Username = username);

var exists = await _context.Users.AnyAsync(u => u.Username = username);

There That's how you use EF to check if a thing that matches the predicate exists

IbraDev💻OP•9mo ago

and for the password the same i guess thats fot the api right?

Angius•9mo ago

var exists = await _context.Users.AnyAsync(u => u.Username = username && u.Password = password);

var exists = await _context.Users.AnyAsync(u => u.Username = username && u.Password = password);

Just be advised that it's shit code That should never have been created It's for whatever touches the database If it's the API, then yes, it's for the API

IbraDev💻OP•9mo ago

Okay thx i will try it out

Angius•9mo ago

I recommend learning LINQ At least the basics, like... .Any() And .Select(), and .ToList(), etc You won't go far with EF if you don't know LINQ

IbraDev💻OP•9mo ago

Yeah im learning the basics now of linq but i have some errors XD username and password are unknown what should be there ?

Angius•9mo ago

The username And the password Wherever you get them from So assuming this is your code still... User.Username and User.PasswordHash

IbraDev💻OP•9mo ago

yeah know thats work but User.Username = username(<- here is the error in little user name he cant find it)

Angius•9mo ago

Wh what

var exists = await _context.Users.AnyAsync(u => u.Username == User.Username && u.Password == User.PasswordHash);

var exists = await _context.Users.AnyAsync(u => u.Username == User.Username && u.Password == User.PasswordHash);

This is how you do it I guess add anonymous functions/lambdas/closures to your learning list

IbraDev💻OP•9mo ago

IDE is german thats why i cant send you the error

Angius•9mo ago

Fixed a typo Should be == of course Not =

IbraDev💻OP•9mo ago

bruh he stillst gives out a error

Angius•9mo ago

Adjust my code to your code Maybe you don't have a DbSet called Users Maybe the password property on your user model is not named Password Maybe your dbcontext is not in a _context field but in ctx Maybe you haven't injected it Don't take this code literally, it only shows the principle Adjust accordingly

IbraDev💻OP•9mo ago

Angius•9mo ago

Great You know what to adjust

IbraDev💻OP•9mo ago

kurumi•9mo ago

lowercase, should be user - not User

IbraDev💻OP•9mo ago

i just saw it XDD yeah now it works now i need my method CheckUser to return something should i just return Ok(exists)

kurumi•9mo ago

better to do:

return exists ? Ok() : NotFound();

return exists ? Ok() : NotFound();

IbraDev💻OP•9mo ago

Okay thxx

kurumi•9mo ago

May I ask you what does /Login do? It should just check existence or returning some data like a tokens?

IbraDev💻OP•9mo ago

but should i do in my front end yeah its checks the existence i think login is not the right name for it

kurumi•9mo ago

Yeah, you should change You should just call this endpoint and provide User as JSON string in body

IbraDev💻OP•9mo ago

kurumi•9mo ago

also it is better to specify it:

[HttpPost("Existence")]
public async Task<IActionResult> CheckUserExistence([FromBody] User user)

[HttpPost("Existence")]
public async Task<IActionResult> CheckUserExistence([FromBody] User user)

your signature should looks like this if I understood u

kurumi•9mo ago

https://learn.microsoft.com/en-us/dotnet/api/system.net.http.httpclient.postasync?view=net-8.0#system-net-http-httpclient-postasync(system-string-system-net-http-httpcontent)

HttpClient.PostAsync Method (System.Net.Http)

Send a POST request to the specified Uri as an asynchronous operation.

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Help making login function c#