如何使用ViewModel数据库优先方法在数据库中保存表？ [英] How do I save a table in a database using a ViewModel database-first approach?

问题描述

我有一个MVC应用程序来更新数据库中的表，但现在我需要添加一个ViewModel，以便我可以在视图页面上显示多个表。但现在的问题是它现在不会保存到数据库中。我正在使用数据库第一种方法（不是代码优先）。



这是我到目前为止：



在我的ViewModel中：

I had an MVC application to update a table in a database, but now I needed to add a ViewModel so that I could have the multiple tables displaying on a view page. But the problem now is that it will not save into the database now. I am using database first approach (not code-first).

Here is what I have so far:

In my ViewModel:

Public Class ClientUserProjectIssue
    Public Property uTable As UserTable
    Public Property issueType As IssueTypeTable
    Public Property IssueTable As IssueTable
End Class

在视图中：

In the view:

@ModelType IssueTracker.ClientUserProjectIssue

@Html.EditorFor(Function(model) model.IssueTable.IssueSummary)
@Html.EditorFor(Function(model) model.IssueTable.IssueDescription)

在我的控制器中：

In my controller:

Public Function UpdateIssue(issue As IssueTracker.ClientUserProjectIssue, objModelMail As IssueTable, command As String) As ActionResult

dbServer.Entry(issue).State = EntityState.Modified
dbServer.SaveChanges()

我现在将得到一个空值，因为我使用的是ViewModel而不是单表。

我试图实现这样的事情：

I will now get a null value because I am using the ViewModel instead of a single table.
I was trying to implement something like this:

Using context As New DbContext()
    Dim dataModel As DatabaseEntities= context.IssueEntiteis.where(Function(x) x.Id = viewModel.Id).First()
    dataModel.Name = viewModel.Name
    dataModel.Type = viewModel.Type
    context.SaveChanges()
End Using

但我是得到错误所以我很确定我不能这样做，因为我首先使用数据库，我如何实现一个viewModel，以便我可以在数据库中保存表？

But I was getting errors so I am pretty sure I can't do it that way because I am using database first, how can I implement a viewModel so that I can save tables in a database?

推荐答案

之前我遇到过这个问题。我发现我实际上没有对数据进行任何更改。我的解决方案是创建一个临时变量并更新如下：

I've run into this before. I found that I hadn't actually made any changes to the data. My solution was to create a temporary variable and update as follows:

Using context As New DbContext()
    Dim dataModel As DatabaseEntities= context.IssueEntiteis.where(Function(x) x.Id = viewModel.Id).First()
    dataModel.Name = viewModel.Name
    dataModel.Type = viewModel.Type
    context.IssueEntiteis.AddOrUpdate(dataModel)
    context.SaveChanges()
End Using

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