Disable/Enable Button in Blazor - Depending on what is in the form

Question

so I am creating this little project in ASP.NET Core, I've got a WEB API, already written but I am struggling with Frontend in Blazor to consume that API. POST, GET HTTP requests work great. I've got this one razor page in which I put some data in (Name, FamilyName etc.) and then I click Send, the data is POSTed to the API.

There is some validation when it comes to that form: Name – at least 5 Characters FamilyName – at least 5 Characters Adress – at least 10 Characters EmailAdress – must be an valid email Age – must be between 20 and 60

and that is all done here with DataAnnotations:

using System.ComponentModel.DataAnnotations;

namespace Blazor.Data
{
    public class Applicant
    {
        public int Id { get; set; }

        [MinLength(5, ErrorMessage ="Name must contain atleast 5 characters.")]
        public string Name { get; set; }

        [MinLength(5, ErrorMessage ="Family Name must contain atleast 5 characters.")]
        public string FamilyName { get; set; }

        [MinLength(10,ErrorMessage ="Address must contain atleast 10 characters.")]
        public string Address { get; set; }

        public string CountryOfOrigin { get; set; }

        [EmailAddress(ErrorMessage ="E-Mail adress is not valid.")]
        public string EmailAddress { get; set; }

        [Range(20,60,ErrorMessage ="Age must be between 20 and 60.")]
        public int Age { get; set; }

        public bool Hired { get; set; }
    }
}

In the Razor page I've got a form to fill out and then send to the API as follows:

@page "/postapplicant"
@using Blazor.Data
@using System.Web
@inherits ApplicantCreateBase

<h1>Create an Applicant</h1>

<p>This component demonstrates posting a data to a Web API.</p>

<EditForm Model="@Applicant" OnValidSubmit="@SendValid">
    <DataAnnotationsValidator />
    <ValidationSummary />

    <hr />
    <div class="form-group row">
        <label for="Name" class="col-sm-2 col-form-label">
            First Name
        </label>
        <div class="col-sm-10">
            <InputText id="Name" class="form-control" placeholder="First Name"
                       @bind-Value="Applicant.Name" />
            <ValidationMessage For="@(() =>Applicant.Name)" />
        </div>
    </div>
    <div class="form-group row">
        <label for="FamilyName" class="col-sm-2 col-form-label">
            Family Name
        </label>
        <div class="col-sm-10">
            <InputText id="FamilyName" class="form-control" placeholder="Family Name"
                       @bind-Value="Applicant.FamilyName" />
            <ValidationMessage For="@(() =>Applicant.FamilyName)" />
        </div>
    </div>
    <div class="form-group row">
        <label for="Address" class="col-sm-2 col-form-label">
            Address
        </label>
        <div class="col-sm-10">
            <InputText id="Address" class="form-control" placeholder="Address"
                       @bind-Value="Applicant.Address" />
            <ValidationMessage For="@(() =>Applicant.Address)" />
        </div>
    </div>
    <div class="form-group row">
        <label for="CountryOfOrigin" class="col-sm-2 col-form-label">
            Country
        </label>
        <div class="col-sm-10">
            <InputSelect id="CountryOfOrigin" class="form-group" placeholder="Country Of Origin"
                         @bind-Value="Applicant.CountryOfOrigin">
                @foreach (var item in Countries)
                {
                    <option>@item.Title</option>
                }
            </InputSelect>
        </div>
    </div>
    <div class="form-group row">
        <label for="EMailAddress" class="col-sm-2 col-form-label">
            E-Mail Address
        </label>
        <div class="col-sm-10">
            <InputText id="EMailAddress" class="form-control" placeholder="E-Mail Address"
                       @bind-Value="Applicant.EmailAddress" />
            <ValidationMessage For="@(() =>Applicant.EmailAddress)" />
        </div>
    </div>
    <div class="form-group row">
        <label for="Age" class="col-sm-2 col-form-label">
            Age
        </label>
        <div class="col-sm-10">
            <InputNumber id="Age" class="form-control" placeholder="Age"
                         @bind-Value="Applicant.Age" />
            <ValidationMessage For="@(() =>Applicant.Age)" />
        </div>
    </div>
    <div class="form-group row">
        <label for="Hired" class="col-sm-2 col-form-label">
            Hired
        </label>
        <div class="col-md-1">
            <InputCheckbox id="Hired" class="form-control" placeholder="Hired"
                           @bind-Value="Applicant.Hired" />
        </div>
    </div>
    <button class="btn btn-primary"  type="submit">Send</button>
    <button class="btn btn-secondary" type="button" @onclick="Reset_Click">Reset</button>

</EditForm>
<Confirm ConfirmationChanged="ConfirmReset_Click" @ref="ResetConfirmation"></Confirm>

Everything works fine and as intended but I want the send button to be enabled only if the whole form is valid according to the rules I have listed above. I know there is this disabled property you can use within a button but I have no idea how to implement this correctly. It seems like such a mess in C# / .net core. Writing a web api from scratch is easier. Help would be appreciated, thank you!

Answer 1

You can access the EditForm's context:

  <button class="btn btn-primary" type="submit" disabled="@(!context.Validate())">Send</button>

Answer 2

In order to avoid showing validation error message when the form is not yet modified (i.e. initially), you can use:

Disabled="@(!context.IsModified() || !context.Validate())"