使用 Blazor 进行客户端验证

Question

我有一个 EditForm，它将 AnimalList 作为具有动物列表的模型。我在动物对象上使用数据注释。在前端，我能够将动物名称列表显示为下拉 + 文本输入组合并将对象添加到该列表中。 因此，您将选择一个动物名称并为该动物分配一个友好的名称。 即我选择“Giraffe”，然后给它一个友好的长颈鹿名字，比如“Brian”。 然后单击添加更多会将空白默认值添加到列表中并可以继续等。 我试图使用数据注释在每一行的文本输入字段上进行一些客户端验证，因为如果我将友好名称留空，我应该会收到一条消息，指出该字段是必需的。最好在我在文本字段内单击并离开之后（我认为是 onBlur？）。

我觉得这应该是标准的，但我觉得使用列表会使标准验证变得更加困难。

如果我输入一些文本，单击离开，然后删除所述文本并单击离开，我会得到验证，这并不理想。 更重要的是，当我单击提交时，我觉得表单应该验证然后不提交，因为应该有消息，但这也不起作用并且提交得很好。我已经尝试过 context.validate 并且它返回 true？

我应该在这里查看某种自定义验证还是应该这样做？

AddAnimals.Razor 代码：

<Css />

<h3>Add your animals</h3>

<EditForm Class="login-form" Model="@AnimalList" OnValidSubmit="SaveAnimals">
    <DataAnnotationsValidator/>

    @if (!string.IsNullOrEmpty(Error))
    {
        <Notification Type="@NotificationType.Error" Message="@Error" />
    }

    <div class="form-group">
        <div class="form-row">
            <div class="col-6">
                <label for="Select">Select Animal</label>
            </div>
            <div class="col">
                <label>Animal Name</label>
            </div>
        </div>
        <ul>
            @foreach (var animalSelection in AnimalList.SelectedAnimals)
            {
                <li>
                    <div class="form-row">
                        <div class="col-6">
                            <select class="form-control" @bind="animalSelection.AnimalName">
                                <option value="" disabled selected hidden>Select...</option>
                                @foreach (var name in AnimalNames)
                                {
                                    <option value="@name">@name</option>
                                }
                            </select>
                        </div>
                        <div class="col">
                            <InputText  class="form-control" @bind-Value="animalSelection.FriendlyName" />
                            <ValidationMessage For="@(() => animalSelection.FriendlyName)" />
                        </div>
                    </div>
                </li>
            }
        </ul>
    </div>
    <div class="form-group">
        <button type="button" class="btn" @onclick="AddMoreAnimals">+ Add More</button>
    </div>
    <div class="form-group">
        <button type="submit" class="btn btn-primary">Continue</button>
    </div>
</EditForm>

@code {

    [Parameter]
    public AnimalList AnimalList { get; set; } = new AnimalList();

    [Parameter]
    public List<string> AnimalNames { get; set; } = new List<string>();

    public string Error { get; set; }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            AnimalNames = AnimalsService.GetAnimals();
            await GetAnimalList();
            if (AnimalList.SelectedAnimals.Count < 1)
            {
                AddMoreAnimals();
            }
            StateHasChanged();
        }
    }

    private async Task GetAnimalList()
    {
        AnimalList.SelectedAnimals = await AnimalsService.GetAnimals();
    }

    private void AddMoreAnimals()
    {
        AnimalList.AddDefault();
    }

    private async void SaveAnimals(EditContext context)
    {
        AnimalList.TrimList();

        foreach (var animal in AnimalsList.SelectedAnimals)
        {
            var response = await AnimalsService.AddAnimal(animal);
            if (response.IsError)
            {
                Error = response.Error;
                StateHasChanged();
                break;
            }
            else
            {
                Error = string.Empty;
            }
        }
    }
}

动物列表

    public class AnimalList
    {
        public List<Animal> SelectedAnimals { get; set; }

        public AnimalList()
        {
            SelectedAnimals = new List<Animal>();
        }

        public void AddDefault()
        {
            SelectedAnimals.Add(new Animal());
        }

        public void TrimList()
        {
            //Trim away possible unused rows
            SelectedAnimals.RemoveAll(
                item => string.IsNullOrEmpty(item.FriendlyName) && 
                    string.IsNullOrEmpty(item.AnimalName));
        }
    }

动物

    public class Animal
    {
        [Required(ErrorMessage = "Animal selection is required")]
        public string AnimalName { get; set; }
        
        [Required(ErrorMessage = "You must enter a name for your Animal")]
        [DisplayFormat(ConvertEmptyStringToNull = true)]
        public string FriendlyName { get; set; }
    }

Answer 1

按照我的建议，我把它分解成一个表格列表。

注意：我使用了页后代码。

AnimalsPage.razor

@page "/animals"

<h3>Add your animals</h3>
<CascadingValue Value="this">
    @foreach (var animal in this.animals)
    {
        <AnimalEditForm @key="animal" Animal="animal" />
    }
</CascadingValue>
<button class="btn mr-1" @onclick="AddAnimalClicked">Add Animal</button>
@if (lastValidateResult)
{
    <button class="btn btn-success" @onclick="SaveAllClicked">Save All</button>
}
else
{
    <button class="btn btn-primary" @onclick="ContinueClicked">Continue</button>
}

AnimalsPage.razor.cs

public partial class AnimalsPage
{
    private void AddAnimalClicked(MouseEventArgs mouseEventArgs)
    {
        this.animals.Add(new Animal());
        this.lastValidateResult = false;
    }

    private void ContinueClicked(MouseEventArgs mouseEventArgs)
    {
        //Your "Trim" function
        List<Animal> emptyAnimals = this.animals.Where(a => a.AnimalName == default && a.AnimalType == default).ToList();
        emptyAnimals.ForEach(a =>
        {
            this.animals.Remove(a);
            this.animalForms.Remove(a);
            this.animalValidationResults.Remove(a);
        });

        this.animalForms.Values.ToList().ForEach(a => a.ShowValidations(true));
        StateHasChanged();
    }

    private void SaveAllClicked()
    {
        //.....
    }

    internal void ChildChangedState(Animal animal, bool result)
    {
        bool prev;
        if (!this.animalValidationResults.ContainsKey(animal))
        {
            prev = false;
            this.animalValidationResults[animal] = prev;
        }
        else
        {
            prev = this.animalValidationResults[animal];
            if (prev != result)
            {
                this.animalValidationResults[animal] = result;
                this.lastValidateResult = this.animalValidationResults.Values.All(a => a);
                StateHasChanged();
            }
        }
    }
    internal Dictionary<Animal, AnimalEditForm> animalForms = new Dictionary<Animal, AnimalEditForm>();
    private readonly Dictionary<Animal, bool> animalValidationResults = new Dictionary<Animal, bool>();
    private readonly List<Animal> animals = new List<Animal>();
    private bool lastValidateResult = false;
}

AnimalEditForm.razor

<EditForm Model="Animal">
    <DataAnnotationsValidator />
    @{if (validatorVisible) { { Validate(context); } } }
    <div class="form-row mb-1">
        <div class="col">
            <InputSelect  class="form-control" @bind-Value="Animal.AnimalType">
                <option value="" selected>Select...</option>
                @foreach (var animalType in animalTypes)
                {
                    <option value=@animalType>@animalType</option>
                }
            </InputSelect>
            <ValidationMessage For="@(() => Animal.AnimalType)" />
        </div>
        <div class="col">
            <InputText class="form-control" @bind-Value="Animal.AnimalName" />
            <ValidationMessage For="@(() => Animal.AnimalName)" />
        </div>
    </div>
</EditForm>

AnimalEditForm.razor.cs

public partial class AnimalEditForm
{
    [Parameter]
    public Animal Animal { get; set; }

    [CascadingParameter]
    public AnimalsPage AnimalsPage { get; set; }

    protected override void OnAfterRender(bool firstRender)
    {
        if (firstRender)
        {
            AnimalsPage.animalForms[Animal] = this;
        }

        base.OnAfterRender(firstRender);
    }
    private IReadOnlyList<string> animalTypes => new[]
    {
        "Eagle",
        "Elephant",
        "Giraffe",
        "Hippopotamus",
        "Horse",
        "Koala",
        "Zebra"
    };

    public bool LastValidateResult { get; private set; }

    private bool validatorVisible = false;

    public void ShowValidations(bool show) => this.validatorVisible = show;

    public void Validate(EditContext editContext)
    {
        LastValidateResult = editContext.Validate();
        AnimalsPage.ChildChangedState(Animal, LastValidateResult);
    }

}

Answer 2

不使用OnValidSubmit 也不使用OnInvalidSubmit，只使用OnSubmit

<EditForm Class="login-form" Model="@AnimalList" OnSubmit="SaveAnimals">

在 SaveAnimal 中，检查列表

private async void SaveAnimals(EditContext context)
{
    bool valid = context.Validate();
    AnimalList.SelectedAnimals.ForEach(x =>
    {
        var field=FieldIdentifier.Create((() => x.FriendlyName));
        context.NotifyFieldChanged(field);
        if (valid)
            valid = context.GetValidationMessages(field)
                       .FirstOrDefault(x => !String.IsNullOrEmpty(x)) == null;

    });
    if (valid)
        Console.WriteLine("Save Animals");
}