NerdDinner 的 AddModelErrors 如何工作？

发布于 2024-07-25 23:04:04 字数 931 浏览 4 评论 0原文

我正在学习 NerDinner 免费教程 http://nerddinnerbook.s3.amazonaws.com/Intro.htm

我必须在第 5 步中的某处，它说为了使代码更简洁，我们可以创建一个扩展方法。我查看了完整的代码，它具有使用扩展方法的功能：

catch
{
    ModelState.AddModelErrors(dinner.GetRuleViolations());
    return View(new DinnerFormViewModel(dinner));
}

然后将其作为扩展方法的定义。

namespace NerdDinner.Helpers {

    public static class ModelStateHelpers {

        public static void AddModelErrors(this ModelStateDictionary modelState, IEnumerable<RuleViolation> errors) {

            foreach (RuleViolation issue in errors) {
                modelState.AddModelError(issue.PropertyName, issue.ErrorMessage);
            }
        }
    }
}

我尝试遵循教程中的内容并结合代码包含的内容，但收到了预期的错误，即不存在仅接受 1 个参数的 AddModelErrors 方法。

我显然在这里遗漏了一些非常重要的东西。它是什么？

原文

I'm going through the NerDinner free tutorial
http://nerddinnerbook.s3.amazonaws.com/Intro.htm

I got to somewhere in Step 5 where it says to make the code cleaner we can create an extension method. I look at the completed code and it has this to use the extension method:

catch
{
    ModelState.AddModelErrors(dinner.GetRuleViolations());
    return View(new DinnerFormViewModel(dinner));
}

And then this as the extension method's definition.

namespace NerdDinner.Helpers {

    public static class ModelStateHelpers {

        public static void AddModelErrors(this ModelStateDictionary modelState, IEnumerable<RuleViolation> errors) {

            foreach (RuleViolation issue in errors) {
                modelState.AddModelError(issue.PropertyName, issue.ErrorMessage);
            }
        }
    }
}

I try to follow what the tutorial says combined with what the code contains but receive the expected error that there is no AddModelErrors method that accepts only 1 argument.

I'm obviously missing something very important here. What is it?

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烏雲後面有陽光 2024-08-01 23:04:04

您需要包含助手参考；

using NerdDinner.Helpers;

然后

using NerdDinner.Models;

检查是否有效并添加错误；

if (!dinner.IsValid)
{
    ModelState.AddModelErrors(dinner.GetRuleViolations());
    return View(dinner);
}

您的晚餐还必须有部分课程；

public partial class Dinner
{
    public bool IsValid
    {
        get { return (GetRuleViolations().Count() == 0); }
    }

    public IEnumerable<RuleViolation> GetRuleViolations()
    {
        if (String.IsNullOrEmpty( SomeField ))
            yield return new RuleViolation("Field value text is required", "SomeField");
    }

    partial void OnValidate(ChangeAction action)
    {
        if (!IsValid)
            throw new ApplicationException("Rule violations prevent saving");
    }
}

不要忘记 RuleViolation 类；

public class RuleViolation
{
    public string ErrorMessage { get; private set; }
    public string PropertyName { get; private set; }

    public RuleViolation(string errorMessage)
    {
        ErrorMessage = errorMessage;
    }

    public RuleViolation(string errorMessage, string propertyName)
    {
        ErrorMessage = errorMessage;
        PropertyName = propertyName;
    }
}

You need to include the helpers reference;

using NerdDinner.Helpers;

and

using NerdDinner.Models;

Then check for valid and add the errors;

if (!dinner.IsValid)
{
    ModelState.AddModelErrors(dinner.GetRuleViolations());
    return View(dinner);
}

You must also have a partial class for your dinner;

public partial class Dinner
{
    public bool IsValid
    {
        get { return (GetRuleViolations().Count() == 0); }
    }

    public IEnumerable<RuleViolation> GetRuleViolations()
    {
        if (String.IsNullOrEmpty( SomeField ))
            yield return new RuleViolation("Field value text is required", "SomeField");
    }

    partial void OnValidate(ChangeAction action)
    {
        if (!IsValid)
            throw new ApplicationException("Rule violations prevent saving");
    }
}

Don't forget the RuleViolation class;

public class RuleViolation
{
    public string ErrorMessage { get; private set; }
    public string PropertyName { get; private set; }

    public RuleViolation(string errorMessage)
    {
        ErrorMessage = errorMessage;
    }

    public RuleViolation(string errorMessage, string propertyName)
    {
        ErrorMessage = errorMessage;
        PropertyName = propertyName;
    }
}

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凉城凉梦凉人心 2024-08-01 23:04:04

如果您收到与此海报相同的错误消息：

“‘System.Web.Mvc.ModelStateDictionary’不包含‘AddModelErrors’的定义，并且没有扩展方法‘AddModelErrors’接受类型为‘System.Web.Mvc’的第一个参数可以找到 .ModelStateDictionary'（您是否缺少 using 指令或程序集引用？）”

您可能遇到此问题：

http://p2p .wrox.com/book-professional-asp-net-mvc-1-0-isbn-978-0-470-38461-9/74321-addmodalerrors-allcountries-page-87-view-data-dictionary.html#post248356

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