C# 在 MVC5 中使用 Html.DisplayFor() 的日期格式
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/19920603/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Date Format using Html.DisplayFor() in MVC5
提问by Greg Hayden
Referencing the answer in this postI added /Views/Shared/DisplayTemplates and added a partial view called ShortDateTime.cshtml as shown below:
参考这篇文章中的答案，我添加了 /Views/Shared/DisplayTemplates 并添加了一个名为 ShortDateTime.cshtml 的部分视图，如下所示：
@model System.DateTime
@Model.ToShortDateString()
When the model contains a value this works and the formatted date is displayed correctly:
当模型包含一个值时，这有效并且格式化的日期显示正确：
@Html.DisplayFor(modelItem => item.BirthDate, "ShortDateTime")
However, if a null value is returned a 'System.InvalidOperationException' is thrown. Indicating:
但是，如果返回空值，则会抛出“System.InvalidOperationException”。表示：
{"The model item passed into the dictionary is null, but this dictionary requires a non-null model item of type 'System.DateTime'."}
{"传入字典的模型项为空，但该字典需要一个非空的'System.DateTime'类型的模型项。"}
My first inclination was to use an if statement inside the partial view but it didn't seem to matter. Without referencing the template null values are handled as in:
我的第一个倾向是在局部视图中使用 if 语句，但这似乎无关紧要。不引用模板空值的处理方式如下：
@Html.DisplayFor(modelItem => item.BirthDate)
but the original issue of formatting remains. When I try to put conditional formatting in the View as follows, it doesn't work but I hoping it's just a syntax thing.
但最初的格式化问题仍然存在。当我尝试按如下方式在视图中放置条件格式时，它不起作用，但我希望它只是一个语法问题。
@Html.DisplayFor(modelItem => item.BirthDate == null) ? string.Empty : (modelItem => item.BirthDate, "ShortDateTime"))
The above results in a different 'System.InvalidOperationException':
以上导致不同的“System.InvalidOperationException”：
{"Templates can be used only with field access, property access, single-dimension array index, or single-parameter custom indexer expressions."}
{"模板只能用于字段访问、属性访问、单维数组索引或单参数自定义索引器表达式。"}
So, is there a way to do conditional formatting in the View to generate just the date from a DateTime value?
那么，有没有办法在视图中进行条件格式设置以仅从 DateTime 值生成日期？
回答by wdosanjos
Have you tried this?
你试过这个吗？
@if (modelItem.BirthDate != null) { Html.DisplayFor(modelItem => item.BirthDate, "ShortDateTime") }
回答by abc123
I guess you should declare the BirthDate property as nullable in model class
我想您应该在模型类中将 BirthDate 属性声明为可为空
public DateTime? BirthDate{ get; set; }
and you must have declared as
你必须声明为
public DateTime BirthDate{ get; set; }
this will expect a value every time.
这每次都会期望一个值。
if you set as nullable it will not expect a value.
如果您设置为可空，则不会期望值。
回答by Vinney Kelly
The problem you're experiencing is that you are passing a nullvalue into a non-nullable model. Change the partial view's model to DateTime?. For example:
您遇到的问题是您将null值传递到不可为空的模型中。将局部视图的模型更改为DateTime?. 例如：
@model DateTime?
@if (!Model.HasValue)
{
<text></text>
}
else
{
@Model.Value.ToShortDateString()
}
Hope this helps.
希望这可以帮助。
回答by Greg Hayden
By applying the conditional statement ahead of the Html helper, only non null values get passed.
通过在 Html 帮助器之前应用条件语句，只会传递非空值。
@if (item.BirthDate != null) { @Html.DisplayFor(modelItem => item.BirthDate , "ShortDateTime")}
