How can the For parameter be dynamically declared in MudTextField with FluentValidation?

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To dynamically declare the For parameter in MudTextField with FluentValidation, you can do the following steps:

1. Define your FluentValidation validator for the corresponding model.

public class LoginValidator : AbstractValidator<LoginModel>
{
    public LoginValidator()
    {
        RuleFor(x => x.Email)
            .NotEmpty().WithMessage("Email is required.")
            .EmailAddress().WithMessage("Invalid email address.");

        RuleFor(x => x.Password)
            .NotEmpty().WithMessage("Password is required.")
            .MinimumLength(6).WithMessage("Password must be at least 6 characters long.");
    }
}

1. Create a MudTextField component in your project and set the variable name for it, for example LoginFormEmail.

<MudTextField Variant="Variant.Outlined"
              Label="Email"
              @bind-Value="@LoginFormEmail"
              Required="true"
              Lines="1"
              Error="Validator.Errors[nameof(LoginFormEmail)]?.FirstOrDefault()?.ErrorMessage" />

1. Add the Validator reference to your MudTextField and set its For parameter to the corresponding property of your model.

<MudTextField Variant="Variant.Outlined"
              Label="Email"
              For="@(() => validator.Email)"
              @bind-Value="@LoginFormEmail"
              Required="true"
              Lines="1"
              Error="Validator.Errors[nameof(LoginFormEmail)]?.FirstOrDefault()?.ErrorMessage" />

1. In the code-behind file of the component, define the Validator property and initialize it with the FluentValidation validator for the corresponding model.

private LoginValidator validator;

protected override void OnInitialized()
{
    base.OnInitialized();
    validator = new LoginValidator();
}

Now, the For parameter of the MudTextField is dynamically declared with FluentValidation. When the form is submitted, the validator will validate the entered value of the MudTextField and display the error message if necessary.