asp.net 验证viewmodel的核心方法

Question

I have a save method which will be called via AJAX post and it passes a object instead of the view model. I parse the object and build the view model. Is there way I can validate that view model object against the data annotation defined on the view model.

In the below example I tried to check the model state but it always is true and is not validating. Is there a way I can run validate against ViewModel?

 public class InvoiceViewModel
    {
    
        public long InvoiceId { get; set;
    
          [Display(Name = "Invoice Number"),Required]
        public string InvoiceNumber { get; set;}
    
        [Display(Name = "Type"),Required]
        public  string InvoiceType { get; set; }
       
        [Display(Name = "Amount"),Required]
        public decimal InvoiceAmount { get; set; }
    }

   
    // controller method
    public JsonResult SaveInvoice([FromBody] object invoice)
    {
         // parse through the invoice object
         var invoiceVM = GetInvoiceViewModel(invoice)
         // I tried the ModelState.IsValid - it did nto work
         // how can I validate invoiceVM against the data annotation defined
    }

     
    public InvoiceViewModel GetInvoiceViewModel(object invoice)
    {
    }

Answer 1

As Camilo Terevinto said,you need to fix how to pass the model to action by ajax.

Before you did the work,you need to know that if the model data you passed contains wrong format,the backend would recieve null model.For example,InvoiceAmount is a decimal type property,if you do set a string like "aaa" or an empty string " " ,it would be null.

And something special about model binding you need to know,the long and decimal type property have default value 0 although you do not pass the property.The Reuiqred attribute does not work for this.

For example,you could see the following gif,I not only do not pass the value but also do not pass the InvoiceAmount property(for how to do not pass the property you could check the following code).But in the backend you could see InvoiceAmount have default value 0:

var data = {
            InvoiceId: $("#InvoiceId").val(),
            InvoiceNumber: $("#InvoiceNumber").val(),
            InvoiceType: $("#InvoiceType").val(),
            //InvoiceAmount: $("#InvoiceAmount").val()  //remove this... 
        }

As a conclusion ,that is to say,for the long and decimal type property,you could not pass wrong format data to them,but you could send model without using these types' properties.

Here is a whole working demo:

View:

@model InvoiceViewModel
<form>
    <div>
        <label asp-for="InvoiceId"></label>
        <input asp-for="InvoiceId" class="form-control" />
    </div>
    <div>
        <label asp-for="InvoiceNumber"></label>
        <input asp-for="InvoiceNumber" class="form-control" />
    </div>
    <div>
        <label asp-for="InvoiceType"></label>
        <input asp-for="InvoiceType" class="form-control" />
    </div>
    <div>
        <label asp-for="InvoiceAmount"></label>
        <input asp-for="InvoiceAmount" class="form-control" />
    </div>
    <div>
        <input type="button" value="post" onclick="PostData()" />
    </div>
</form>
@section Scripts
{
<script>
    function PostData() {
        var data = {
            InvoiceId: $("#InvoiceId").val(),
            InvoiceNumber: $("#InvoiceNumber").val(),
            InvoiceType: $("#InvoiceType").val(),
            InvoiceAmount: $("#InvoiceAmount").val()
        }
        console.log(data);
        console.log(JSON.stringify(data));
        $.ajax({
            url: "/Home/SaveInvoice",
            type: "POST",
            contentType: "application/json; charset=utf-8",  //be sure add this...
            data: JSON.stringify(data),
            success: function (res) {
                alert(res.message);
            }
        })
    }
</script>
}

Controller:

public JsonResult SaveInvoice([FromBody]InvoiceViewModel invoice)
{
    if (ModelState.IsValid)
    {
        return Json(new { message = "Success" });
    }
    return Json(new { message = "Error" });
        
}

Result: