DropDownList.DataTextField不能绑定到数据集？(DropDownList.DataTextField can't be bound to a dataset?)

我正在尝试将dataset绑定到dropdownlist ，该dropdownlist会抛出HttpException

这就是我想要做的

if (dsGroupsNotOnFestival.Tables[0].Rows.Count > 0) { //Bind dataset to new group selection ddlNewGroup.DataSource = dsGroupsNotOnFestival.Tables[0].DefaultView; ddlNewGroup.DataValueField = "band_id"; ddlNewGroup.DataTextField = "band_naam"; ddlNewGroup.DataBind(); } else { ddlNewGroup.Items.Add(new ListItem("No groups to add")); }

异常消息：

DataBinding: 'System.Data.DataRowView' does not contain a property with the name 'band_naam'.

我绝对肯定dataset包含一个标题为band_naam的列。 如您所见，绑定DataTextField时抛出异常，这意味着DataValueField绑定正确，对吧？

编辑：

这是存储过程：

USE [groep2_festivals] GO /****** Object: StoredProcedure [dbo].[GetGroupsOfFestival] Script Date: 14-05-13 12:31:18 PM ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author: Robbie Vercammen -- Create date: 2013-05-09 -- Description: Getting all groups for a defined festival -- ============================================= ALTER PROCEDURE [dbo].[GetGroupsOfFestival] ( @festId nvarchar(4) ) AS BEGIN DECLARE @query varchar(255) SELECT b.*, p.* FROM bands b JOIN bandsperfestival bpf ON b.band_id = bpf.band_id JOIN podia p ON p.pod_id = bpf.pod_id WHERE fest_id LIKE @festId EXEC(@query) END

注意b.*和bands b ？ 现在这个表：

这个存储过程已经多次使用，所以我很确定它能正常工作。 但这里可能是我忘记提及的最重要的代码：

//Filling dataset with groups not on this festival dsGroupsNotOnFestival.Tables.Add(new DataTable()); foreach (DataRow row in dsGroupsAll.Tables[0].Rows) { if (!dsGroupsPerFestival.Tables[0].Rows.Equals(row)) { dsGroupsNotOnFestival.Tables[0].ImportRow(row); } }

再一次， DataSet dsGroupsAll之前已经使用过，所以数据存在:)

@manish mishra dsGroupsAll充满了上面相同的存储过程。 为了证明那里有实际的数据：

对于那些仍然关注的人，我已经确认dsGroupsNotOnFestival有14行。 当我试图以一种简单的方式获取值时，例如：

String strResult = dsGroupsNotOnFestival.Tables[0].Rows[0][0].ToString();

我得到一个例外，说无法找到第0列......为什么会这样？

I'm trying to bind a dataset to a dropdownlist, which throws a HttpException

Here's what I'm trying to do

if (dsGroupsNotOnFestival.Tables[0].Rows.Count > 0) { //Bind dataset to new group selection ddlNewGroup.DataSource = dsGroupsNotOnFestival.Tables[0].DefaultView; ddlNewGroup.DataValueField = "band_id"; ddlNewGroup.DataTextField = "band_naam"; ddlNewGroup.DataBind(); } else { ddlNewGroup.Items.Add(new ListItem("No groups to add")); }

The exception message:

DataBinding: 'System.Data.DataRowView' does not contain a property with the name 'band_naam'.

I'm absolutely positive that the dataset contains a column with the title band_naam. As you can see, the exception is thrown when binding the DataTextField, meaning that the DataValueField is bound correctly, right?

EDIT:

This is the stored procedure:

USE [groep2_festivals] GO /****** Object: StoredProcedure [dbo].[GetGroupsOfFestival] Script Date: 14-05-13 12:31:18 PM ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO -- ============================================= -- Author: Robbie Vercammen -- Create date: 2013-05-09 -- Description: Getting all groups for a defined festival -- ============================================= ALTER PROCEDURE [dbo].[GetGroupsOfFestival] ( @festId nvarchar(4) ) AS BEGIN DECLARE @query varchar(255) SELECT b.*, p.* FROM bands b JOIN bandsperfestival bpf ON b.band_id = bpf.band_id JOIN podia p ON p.pod_id = bpf.pod_id WHERE fest_id LIKE @festId EXEC(@query) END

Notice the b.* and bands b? Now here that table:

This stored procedure has been used on multiple occasions, so I'm pretty sure that it works correctly. But here's perhaps the most important code that I forgot to mention:

//Filling dataset with groups not on this festival dsGroupsNotOnFestival.Tables.Add(new DataTable()); foreach (DataRow row in dsGroupsAll.Tables[0].Rows) { if (!dsGroupsPerFestival.Tables[0].Rows.Equals(row)) { dsGroupsNotOnFestival.Tables[0].ImportRow(row); } }

And once again, the DataSet dsGroupsAll has been used before so the data is present :)

@manish mishra dsGroupsAll is filled with the same stored procedure above. To prove that there is actually data in there:

For those still following, I've confirmed that there are 14 rows in dsGroupsNotOnFestival. When i'm trying to get a value in a simple way, for example:

String strResult = dsGroupsNotOnFestival.Tables[0].Rows[0][0].ToString();

I get an exception saying that column 0 could not be found... why is that?

最满意答案

我绝对肯定数据集包含一个标题为band_naam的列。

我理解你的感受，但我绝对肯定没有一个，因为这个错误是非常明确的：

不包含名为'band_naam'的属性

再看一下填充DataSet的代码。 DefaultView是DataTable的完美图像，当然它是查询的结果集，因此您用来填充此DataTable的查询缺少此字段。

也许它是一个计算字段，你忘了AS关键字给它一个列名。

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编辑

根据您的反馈（即查询和架构的屏幕截图），我会说Habib可能会在评论中直接点击它，更改此行：

ddlNewGroup.DataSource = dsGroupsNotOnFestival.Tables[0].DefaultView;

到这一行：

ddlNewGroup.DataSource = dsGroupsNotOnFestival.Tables[0];

我个人从未遇到过绑定到DefaultView的问题，但我觉得还没有任何其他可能性。

I'm absolutely positive that the dataset contains a column with the title band_naam.

I understand how you feel, but I'm absolutely positive that there isn't one because that error is extremely explicit:

does not contain a property with the name 'band_naam'

Have another look at the code that fills that DataSet. The DefaultView is a perfect image of the DataTable, which of course is the result set of your query, so the query you're using to fill this DataTable is missing this field.

Maybe it's a calculated field and you forgot the AS keyword to give it a column name.

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EDIT

Based on your feedback (i.e. screenshots of the queries and schema), I'm going to say Habib probably hit it right on the head in the comments, change this line:

ddlNewGroup.DataSource = dsGroupsNotOnFestival.Tables[0].DefaultView;

to this line:

ddlNewGroup.DataSource = dsGroupsNotOnFestival.Tables[0];

I personally have never had a problem binding to a DefaultView but I don't feel there are any other possibilities left.