Spring request parameter is missing

I’m trying to register a user by sending the username, password, firstName and lastName from the c# client to the java application using spring. In the java application, it gets the username and password but firstName and lastName get lost.

This is the error I get:

[org.springframework.web.bind.MissingServletRequestParameterException: Required request parameter 'firstName' for method parameter type String is not present]

This is the c# method I’m using to send the parameters to the java application:

public async Task<User> RegisterUserAsync(string username, string password, string firstName, string lastName)
        {
            Console.WriteLine("Registering...");
            HttpResponseMessage responseMessage =
                await Client.GetAsync($"http://localhost:8080/user/register?username={username}&password={password}&firstname={firstName}&lastname={lastName}");
            if (responseMessage.StatusCode == HttpStatusCode.OK)
            {
                string userAsJson = await responseMessage.Content.ReadAsStringAsync();
                User resultUser = JsonSerializer.Deserialize<User>(userAsJson);
                Console.WriteLine("Registered");
                return resultUser; //EXPECTED A USUAL USER TO BE RETURNED 
            }

            throw new Exception("User could not be registered");
        }

When debugging it shows that all parameters have correct values, but java does not receive them

Java application register method:

@GetMapping("/register")
    public ResponseEntity<User> ValidateRegister(@RequestParam String username, @RequestParam String password, @RequestParam String firstName, @RequestParam String lastName)
    {
        try{
            System.out.println(username);
            User user = userService.ValidateRegister(username,password,firstName,lastName);

            if(user == null) {
                return ResponseEntity.notFound().build();
            }
            return ResponseEntity.ok(user);
        }
        catch (Exception e)
        {
            System.out.println(e.getMessage());
            return ResponseEntity.badRequest().build();
        }
    }

If I put firstName and lastName as required = false, then it registers the user only with username and password.

The question is why does the username and password get through but firstName and lastName doesn’t ?

>Solution :

Because you do not explicitly specify the name of the parameter, which makes Spring parse the parameters by the name of the variables. And they are different for you: in С# you pass firstname and lastname, but in java your parameters are called firstName and lastName

Try it in java-code:

@RequestParam(name = "firstname") String firstName, @RequestParam(name = "lastname") String lastName

or (better) fix your C# client:

Client.GetAsync($"http://localhost:8080/user/register?username={username}&password={password}&firstName={firstName}&lastName={lastName}");