I am trying to set the initial values for a list box using asp.net mvc 3. It does fill in the options, but doesn't select them.
Here is my code. This attempt uses a hardcoded set of values
#Html.ListBoxFor(Function(model) model.PageTags, New MultiSelectList(Model.PageTags, "ID", "TagEn", New Integer(){1,2})
I have also tried an example that I would expect would select all the values.
#Html.ListBoxFor(Function(model) model.PageTags, New MultiSelectList(Model.PageTags, "ID", "TagEn", Model.PageTags)
You have to pass the selected values as an enumerable of "values" (and not an enumerable of the original "items"). In your case this should be a list of IDs. E.g. to select all try to pass the selected values like this: Model.PageTags.Select(i => i.ID)
Related
I have a listbox in VB.NET that allows users to select multiple categories. I need to put these categories into a database and need the index value from the listbox of the categories as the database works off IDs. SelectedItems (with an s) does not work in the net application.
I have tried the following code:
For Each category As ListItem In CategoryListBox.Items
If category.Selected Then
Dim courseCategory As New CourseCategory
courseCategory.CourseID = course.ID
courseCategory.CategoryID = CategoryListBox.SelectedIndex
Using courseCategoryEntities As New Eng_NWDTrainingWebsiteEntities
courseCategoryEntities.CourseCategories.Add(courseCategory)
courseCategoryEntities.SaveChanges()
End Using
End If
Next
When iterating through the loop the code that is:
courseCategory.CategoryID = CategoryListBox.SelectedIndex
works correctly the first time around.
On the second iteration of the loop, it goes to the next selected item however returns the index for the first selected value. How do I return the values of the other indexes selected?
It depends on what ID you need to pass to your database. If it is truly the index of the ListItem in the ListBox, then you would use:
courseCategory.CategoryID = CategoryListBox.Items.IndexOf(category);
That may not be the best approach however. Maybe the order of the ListItems changes, messing up your indexes. You probably want to store the actual CategoryID on each ListItem. The Value property works well for that. You set the column you want as the DataValueField like so:
<asp:ListBox ID="CategoryListBox" runat="server"
DataValueField="CategoryID "></asp:ListBox>
So as you are looping through each ListItem in the ListBox and checking if it is selected, just use it's Value property.
For Each category As ListItem In CategoryListBox.Items
If category.Selected Then
Dim courseCategory As New CourseCategory
courseCategory.CourseID = course.ID
courseCategory.CategoryID = category.Value;
Using courseCategoryEntities As New Eng_NWDTrainingWebsiteEntities
courseCategoryEntities.CourseCategories.Add(courseCategory)
courseCategoryEntities.SaveChanges()
End Using
End If
Next
Fixed the code by deselecting the item in the listbox after it was successfully saved.
End Using
category.Selected = False
End If
This solved my problem.
i am bit confused by the nature and working of query , I tried to access database which contains each name more than once having same EMPid so when i accessed it in my DROP DOWN LIST then same repetition was in there too so i tried to remove repetition by putting DISTINCT in query but that didn't work but later i modified it another way and that worked but WHY THAT WORKED, I DON'T UNDERSTAND ?
QUERY THAT DIDN'T WORK
var names = (from n in DataContext.EmployeeAtds select n).Distinct();
QUERY THAT WORKED of which i don't know how ?
var names = (from n in DataContext.EmployeeAtds select new {n.EmplID, n.EmplName}).Distinct();
why 2nd worked exactly like i wanted (picking each name 1 time)
i'm using mvc 3 and linq to sql and i am newbie.
Both queries are different. I am explaining you both query in SQL that will help you in understanding both queries.
Your first query is:
var names = (from n in DataContext.EmployeeAtds select n).Distinct();
SQL:-
SELECT DISTINCT [t0].[EmplID], [t0].[EmplName], [t0].[Dept]
FROM [EmployeeAtd] AS [t0]
Your second query is:
(from n in EmployeeAtds select new {n.EmplID, n.EmplName}).Distinct()
SQL:-
SELECT DISTINCT [t0].[EmplID], [t0].[EmplName] FROM [EmployeeAtd] AS
[t0]
Now you can see SQL query for both queries. First query is showing that you are implementing Distinct on all columns of table but in second query you are implementing distinct only on required columns so it is giving you desired result.
As per Scott Allen's Explanation
var names = (from n in DataContext.EmployeeAtds select n).Distinct();
The docs for Distinct are clear – the method uses the default equality comparer to test for equality, and the default comparer sees 4 distinct object references. One way to get around this would be to use the overloaded version of Distinct that accepts a custom IEqualityComparer.
var names = (from n in DataContext.EmployeeAtds select new {n.EmplID, n.EmplName}).Distinct();
Turns out the C# compiler overrides Equals and GetHashCode for anonymous types. The implementation of the two overridden methods uses all the public properties on the type to compute an object's hash code and test for equality. If two objects of the same anonymous type have all the same values for their properties – the objects are equal. This is a safe strategy since anonymously typed objects are essentially immutable (all the properties are read-only).
Try this:
var names = DataContext.EmployeeAtds.Select(x => x.EmplName).Distinct().ToList();
Update:
var names = DataContext.EmployeeAtds
.GroupBy(x => x.EmplID)
.Select(g => new { EmplID = g.Key, EmplName = g.FirstOrDefault().EmplName })
.ToList();
I have a SQL Server table tblApplications with some columns... one of the columns is called Content and has XML values like in the following Image:
when i clicked on the value of content in the above image it displays like following in new tab
I want to get the value using id from the xml value of dataitem that is under the datagroupItem of datagroup as selected in following image, using query from the tblApplications
How to get the value from the content using id?? E.g. I want to get the value of id of dataitem = 'ForeNames'
How to get it using query????
You could try this query:
SELECT a.application_id,
x.y.query('.') AS DataItemNode,
x.y.value('(#type)[1]','NVARCHAR(50)') AS TypeAttr,
x.y.value('(#value)[1]','NVARCHAR(50)') AS ValueAttr
FROM dbo.tblApplications a
CROSS APPLY a.Content.nodes('/XmlDataPairDocument/dataitem/datagroup/datagroupitem/dataitem[#id="forenames"]') x(y)
or
DECLARE #id NVARCHAR(50);
SET #id='forenames';
SELECT a.application_id,
x.y.query('.') AS DataItemNode,
x.y.value('(#type)[1]','NVARCHAR(50)') AS TypeAttr,
x.y.value('(#value)[1]','NVARCHAR(50)') AS ValueAttr
FROM dbo.tblApplications a
CROSS APPLY a.Content.nodes('/XmlDataPairDocument/dataitem/datagroup/datagroupitem/dataitem[#id = sql:variable("#id")]') x(y)
Another similar questions-answers: here #1, here #2
I've been looking for a way to control the text that appears in a particular column of a GridView.
For example consider a database with two tables Student and Class.
I want to add a column to the GridView which print out all the students in the Database, the column will show the student's class name, how can do it? (I can normally print the ClassId since its a FK in the student table)
I want to add a column to the GridView which print all the classes, the column will count the number of students in each class, how can I do it?
1- You can do that simply with inner join or a stored procedure to get the class name beside all the data you need in your query.
2- More than one way to do what you want:
For example:
you can add a column to your data table (empty column ), and fill it later through using Sum() aggregate function in a query.
DataTable result_dt = DAL_Helper.Return_DataTable(sqlSelect);//your original query
result_dt.Columns.Add("NumberOfStudent");
result_dt.Columns["NumberOfStudent"].DataType = typeof(string);
result_dt.Columns["NumberOfStudent"].MaxLength = 255;
if (result_dt.Rows.Count > 0)
{
for (int i = 0; i < result_dt.Rows.Count; i++)
{
//Here u can fill your new empty column.
}
}
result_dt.AcceptChanges();
After you return your customized data table(as a data source), you can bind it to the grid view.
Another solution : add an empty column to the grid view and in the RowDataBound event of the grid view you can fill this column through some loop and you can use LINQ to help you in getting the summation.
Its like I have multiselect option in Jqgrid in which i want to pass the selected rows value to the server and based on the value i will delete the rows. I dont want to have the ids to do my work. For the Single row i get the cell value and delete using the same. But for multi select its not the case. In getGridParam('selarrrow'); I use this to fetch the selected rows bu the values are not getting populated. Please help me out in doing the same
When i use the following code as i saw in some sample question i can fetch the value for the single row selection but when i select multiple rows then i pass it says like "FALSE" or "UNDEFINED". What can be the issue. var grid = jQuery('#list'); var sel_id = grid.jqGrid('getGridParam', 'selarrrow'); var myCellData = grid.jqGrid('getCell', sel_id, 'CountryId');
I got this done by using the for loop for getting the selected rows id
i did some thing like this and I am able to fetch the value. Thought this might help others too please check it
var myrow;
var id = jQuery("#List").jqGrid('getGridParam','selarrrow');
if(id.length)
{
for (var i=0;i<id.length;i++) // For Multiple Delete of row
{
myrow = jQuery("#List").jqGrid('getCell',id[i],'ticker');
}
}