在 ASP.NET Core MVC 中一次验证两个属性

Question

我有以下 ViewModel；

public class MyViewModel {
    [Required(ErrorMessage = "Location is required")]
    [Range(SOME_RANDOM_COORDINATE, SOME_RANDOM_COORDINATE, ErrorMessage = "Keep location within map bounds")]
    public double? Latitude { get; set; }

    [Required(ErrorMessage = "Location is required")]
    [Range(SOME_RANDOM_COORDINATE, SOME_RANDOM_COORDINATE, ErrorMessage = "Keep location within map bounds")]
    public double? Longitude { get; set; }
}

我使用 OpenStreetMap 作为这些纬度和经度值的输入，并且我想使用 ViewModel 中的属性添加客户端和服务器端验证。我正在创建两个 html 输入字段（均隐藏）。提交表单（而不是设置位置）时，我自然会得到两次“需要位置”。如何将这两个属性组合在一起进行验证？

查看；

<form asp-area="" asp-controller="Report" asp-action="Create" method="post" enctype="multipart/form-data">
    <h4>@ViewData["Title"]</h4>
    <hr />
    <div class="form-group">
        <input id="latitude" type="hidden" asp-for="@Model.Latitude" class="form-control" />
        <span asp-validation-for="@Model.Latitude" class="text-danger"></span>
    </div>
    <div class="form-group">
        <input id="longitude" type="hidden" asp-for="@Model.Longitude" class="form-control" />
        <span asp-validation-for="@Model.Longitude" class="text-danger"></span>
    </div>
</form>

Answer 1

您可以尝试使用自定义属性来验证坐标对。

在您的模型中，我将删除 [Required] 属性并将其替换为自定义验证属性。这些值可以在模型中设置为默认值，以便初始视图最初不会引发错误。然后，您的控制器可以在呈现视图后将坐标覆盖为您想要的任何内容。

public class MyCoordinateModel {    
    [Range(SOME_RANDOM_COORDINATE, SOME_RANDOM_COORDINATE, ErrorMessage = "Keep location within map bounds")]
    [CustomCoordinate("Longitude", ErrorMessage = "{0} field has not been set.")]
    public double? Latitude { get; set; }

    [Range(SOME_RANDOM_COORDINATE, SOME_RANDOM_COORDINATE, ErrorMessage = "Keep location within map bounds")]
    [CustomCoordinate("Latitude", ErrorMessage = "{0} field has not been set.")]
    public double? Longitude { get; set; }

    MyCoordinateModel()
    {
        Longitude = 0;
        Latitude = 0;
    }
}

自定义属性将是这样的，错误消息有条件地显示为无效的属性：

[AttributeUsage(AttributeTargets.Property | 
  AttributeTargets.Field, AllowMultiple = false)]
public class CustomCoordinateAttribute : ValidationAttribute
{
    private readonly string _requiredProperty;

    public CustomCoordinateAttribute(public double? requiredValue)
    {
         _requiredProperty = requiredValue;
    }

    protected override ValidationResult IsValid(object value, 
       ValidationContext validationContext)
    {
        var currentValue = (double)value;

        var property = 
            validationContext.ObjectType.GetProperty(_requiredProperty);

        if (property == null)
            throw new ArgumentException("Specified property name not found");

        var otherValue = 
            (DateTime)property.GetValue(validationContext.ObjectInstance);

        if ((currentValue == null) || (otherValue == null))
        {
            return new ValidationResult("None of the coordinates are defined");
        }

        if ((currentValue == null) && (otherValue != null))
        {
            return new ValidationResult(String.Format(
                ErrorMessageString, currentValue));
        }

        if ((currentValue != null) && (otherValue == null))
        {
            return new ValidationResult(String.Format(
                ErrorMessageString, otherValue);
        }

        if ((currentValue < 0) || (otherValue < 0))
        {
            return new ValidationResult("Coordinates cannot be negative");
        }

        return ValidationResult.Success;
    }
}

Answer 2

你可以在表单提交之前使用ajax进行验证，这里有一个demo：

行动：

public IActionResult Verify(double? Latitude,double? Longitude)
        {
            if (Latitude==null||Longitude==null)
            {
                return Json("Location is required");
            }

            return Json(true);
        }

MyViewModel：

public class MyViewModel {
    [Range(SOME_RANDOM_COORDINATE, SOME_RANDOM_COORDINATE, ErrorMessage = "Keep location within map bounds")]
    public double? Latitude { get; set; }

    [Range(SOME_RANDOM_COORDINATE, SOME_RANDOM_COORDINATE, ErrorMessage = "Keep location within map bounds")]
    public double? Longitude { get; set; }
}

查看：

  <form asp-area="" asp-controller="Report" asp-action="Create" method="post" enctype="multipart/form-data">
    <h4>@ViewData["Title"]</h4>
    <hr />
    <div class="form-group">
        <input id="latitude" hidden asp-for="Latitude" class="form-control" value="1"/>
        <span asp-validation-for="Latitude" class="text-danger"></span>
    </div>
    <div class="form-group">
        <input id="longitude" hidden asp-for="Longitude" class="form-control"/>
        <span asp-validation-for="Longitude" class="text-danger"></span>
    </div>
    <div>
        <span class="text-danger field-validation-error" id="error"></span>
    </div>
    <button>submit</button>
</form>
@section Scripts {
    @{ await Html.RenderPartialAsync("_ValidationScriptsPartial"); }
<script>
    
    $("form").submit(function (e) {
        $.ajax({
            type: "GET",
            url: 'Verify?Latitude=' + $("#latitude").val() + '&Longitude=' + $("#longitude").val(),
            success: function (data) {
                if (data != "valid") {
                    $("#error").html(data);
                } else {
                    $('form').unbind().submit();
                }
            }

        })
        return false;
        
        
    })
   
</script>
}

结果：