ASP.NET自定义模型绑定:DateTime [英] ASP.NET Custom Model Binding: DateTime

问题描述

问题

The problem

这时我遇到一个问题，我的Get操作试图读取发送的不同格式的DateTime参数.

At this point I have a problem where my Get action is trying to read a DateTime parameter in a diferent format that is sent.

虽然发送的DateTime具有以下格式:0:dd/MM/yyyy Get Actions预期:0:MM/dd/yyyy

While the DateTime sent has this format: 0:dd/MM/yyyy The Get Actions expects: 0:MM/dd/yyyy

解决方案(也许)

The solution (maybe)

为了更改获取"操作的期望，我使用的是自定义模型绑定".

In order to change what the Get action is expecting I'm using a Custom Model Binding.

GET操作

    public async Task<IActionResult> Details(int? id, [ModelBinder(typeof(PModelBinder))]DateTime date)

ModelBinder类

现在这里缺少一些东西，我不知道如何正确完成它:

Now here are a few things that are missing and I don't know how to complete it properly:

public class PModelBinder : IModelBinder
{
    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        string theDate = bindingContext.HttpContext.Request.QueryString["date"]; 
        //What should I write inside the []? 
        //I've tried QueryString["date"] which is the name of the parameter but it says is wrong
        DateTime dt = new DateTime();
        bool success = DateTime.TryParse(date); //Should I apply ParseExact? How should I do it?
        if (success)
        {
            return new //what should I be returning here? dt?
        }

    }
}

由于我刚刚开始了解自定义模型绑定，因此我在上面的代码中将几个问题标记为注释.希望任何人都能给我一些建议.

I've several questions marked as comments in the code above since I'm just starting to understand Custom Model Binding. Hope anyone can give me some advice.

我正在关注这篇文章:

https://weblogs.asp.net/melvynharbour/mvc-modelbinder和本地化

但这是从 2008 !!! 开始的，尽管它似乎是有效的，因为这正是我的GET Action(不同的日期格式)所遇到的问题

But it's from 2008!!!, Although it seems valid since it's exactly the problem I'm having with my GET Action (diferent date formats)

更新:附加信息

Update: aditional information

参数日期定义为:

    [DisplayFormat(DataFormatString = "{0:dd/MM/yyyy}", ApplyFormatInEditMode = true)]
    public DateTime FechaLInicioLiq { get; set; }

以及调用该GET Action的URL构建具有针对date参数的以下结构:

and the URL build when calling that GET Action has this structure for the date parameter:

date=10%2F11%2F2017%200%3A00%3A00

推荐答案

您的模型绑定程序实现存在几个问题:

You have several issues with your model binder implementation:

1. 请勿对参数名称(date)进行硬编码.请使用bindingContext.ModelName.
2. 如果没有实际提供价值，您应该处理情况.您可以通过比较IValueProvider.GetValue()和ValueProviderResult.None的结果来检查它.

1. Do not hardcode parameter name (date). Use bindingContext.ModelName instead.
2. You should handle situation if value was not actually provided. You could check it by comparing result of IValueProvider.GetValue() with ValueProviderResult.None.

以下是示例DateTime模型绑定程序，可以完成您需要的操作:

Here is sample DateTime model binder that accomplish what you need:

public class DateTimeModelBinder : IModelBinder
{
    private readonly IModelBinder baseBinder = new SimpleTypeModelBinder(typeof(DateTime));

    public Task BindModelAsync(ModelBindingContext bindingContext)
    {
        var valueProviderResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
        if (valueProviderResult != ValueProviderResult.None)
        {
            bindingContext.ModelState.SetModelValue(bindingContext.ModelName, valueProviderResult);

            var valueAsString = valueProviderResult.FirstValue;

            //  valueAsString will have a string value of your date, e.g. '31/12/2017'
            var dateTime = DateTime.ParseExact(valueAsString, "dd/MM/yyyy", CultureInfo.InvariantCulture);
            bindingContext.Result = ModelBindingResult.Success(dateTime);

            return Task.CompletedTask;
        }

        return baseBinder.BindModelAsync(bindingContext);
    }
}

这篇关于ASP.NET自定义模型绑定:DateTime的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！