When using the asp:boundfield, can I call a C# function that return a string which corresponds to the column name instead of writing the column itself?
<asp:BoundField DataField="Notes" HeaderText="Notes"/>
Instead of having DataField="Notes", I want to have DataField=FUNCTION_NAME.
I tried using the following but it didn't work:
DataField=<% FUNCTION_NAME %>
Try this:
DataField="<%=FUNCTION_NAME %>" (extra equals)
What you had was simply an embedded code block which didn't have an output. However the = produces output to the page (similar to response.write()).
See the difference here
Related
I am trying to limit the characters displayed in ASP.NET Label controls that have their Text values databound to a SQL Database. If the field in the database is not NULL, I do not have any trouble. If they are NULL, I get the exception "Object reference not set to an instance of an object."
My code is as follows:
<asp:Label ID="LabelDescriptionLabel" runat="server" Text='<%# IIf(Not IsDBNull(Item.LabelDescription), IIf(Item.LabelDescription.ToString.Length > 30, Left(Item.LabelDescription, 30) & "...", Item.LabelDescription), Item.LabelDescription)%>' />
I have also tried the following, without any luck:
<asp:Label ID="LabelDescriptionLabel" runat="server" Text='<%# IIf(Not IsNothing(Item.LabelDescription), IIf(Item.LabelDescription.ToString.Length > 30, Left(Item.LabelDescription, 30) & "...", Item.LabelDescription), Item.LabelDescription)%>' />
I am using ASP.NET with VB.NET. I have tried using the CSS "text-overflow: ellipsis" method as well, but I had some table formatting issues that I have not resolved.
Is there a way to handle these NULL values and prevent run-time exceptions?
Thanks!
One problem you are having is that the old IIF is a function which evaluates all the parts before it decides what to return.
IIF(Not IsDBNull(Item.LabelDescription), TruePart, FalsePart)
It does not matter if the expression is true or not, the TruePart and
FalsePart statements will always be executed. Since they include references to something which may be DBNull/Nothing/null, you get an error.
Something else though is that Nothing is not the same as DBNull, and if Item is an Object which can be Nothing/null, then testing the description of Nothing/null will be problematic.
The If Operator has been available since abut 2008. The structure is the same but it only evaluates the test condition and the True or False expression which applies:
If( Condition, TruePart, FalsePart )
The "short circuiting" prevents the expression/Part which does not apply from being evaluated. As long as the rest of the code is valid, you should be able to just clip one of the Is from the IIF functions.
Since you want to the object Nothing I would use the Nothing keyword rather than the VB IsNothing function:
If(Item IsNot Nothing),
If(Item.LabelDescription.ToString.Length > 30, x, y), y)
The If operator is not the same as the If/Then/Else statement block.
I know the error is caused by the <%# Eval("NodeID")%> statement. When I put a literal integer, it works fine. I tried changing the outside double quotes of the WhereCondition to single quotes, and the inside quotes to double quotes, but this throws an exception.
<cms:CMSRepeater ID="subcatPreviewImages" Path= '<%# Eval("NodeAliasPath") + "/%" %>' runat="server" ClassNames="CMS.MenuItem" TransformationName="EcommerceSite.Transformations.EMCategorySmallImagePreview" OrderBy="NodeLevel, NodeOrder, NodeName" MaxRelativeLevel="4" WhereCondition="DocumentMenuItemHideInNavigation='false' AND NodeParentID= <%# Eval("NodeID")%> AND NodeLevel=3" />
You need to build your string inside the databind tag like you did with the NodeAliasPath property:
WhereCondition='<%# "DocumentMenuItemHideInNavigation='false' AND NodeParentID=" + Eval("NodeID") + " AND NodeLevel=3" %>'
If you are having trouble with the mixed ' and " characters, you may want to move the logic that builds the expression into a function in your page:
public string GetWhereCondition(SomeType dataItem) {
return "..." + dataItem.NodeID + "...";
}
And the your tag changes to:
WhereCondition="<%# GetWhereCondition(Container.DataItem) %>"
Disclaimer: function and type names are made up for example only -- please use appropriately named functions and replace my poorly-named ones.
I want to use webdings characters in .net application.
Does anyone know how to do this.
I tried using :
ASPX:
<asp:Label ID="lblSample" runat="server" Font-Names="Webdings" ></asp:Label>
CODE BEHIND:
lblSample.Text = "0x61"
But it doesn't displaying properly.
As can be seen in any ASCII table, character 0x61 is a lower case a.
You are trying to output the string "0x61" instead of a lower case a.
You should be doing this:
lblSample.Text = "a"
I am doing some labeling. I would like to add a resource key (s, sec) to one of my combo boxes with item[3sec, 5sec, 10sec, 30sec ...] and use it like:
Text="3<%$ Resources: myResource, s%>" to get comboBoxItem 3sec,
Text="5<%$ Resources: myResource, s%>" to get comboBoxItem 5sec ...
But I find that the server will treat this as plain text.
Do I need to define each item in a separate resource key pair?
Consider defining your resource file entry value as follows:
{0}sec
And then
String.Format(Resources.myResource.s, "3")
You can try creating your own custom expression builder. They are really powerful if you want to achieve what you have asked in your question.
Or, you can always do it using server-side code.
You could do it like this (with a DataBind() call somewhere):
Text='<%# "3" + Resources.myResource.s %>'
Edit: You can also do this from code behind. Something like this:
int[] times = new int[]{ 3, 5, 10, 30 };
foreach (int time in times)
{
string text = time.ToString() + Resources.myResource.s;
cbo.Items.Add(new ListItem(text, time.ToString()));
}
Edit 2: As per Muhammad's observation the first example doesn't work for this. I've used it for other controls, and I didn't see that for the current case it's not correct. Given this I would fill the control from code behind.
<asp:Repeater ID="rptLessons" runat="server">
<ItemTemplate>
<tr>
<td><%#Eval("fullname")%></td>
<td><%#isCompleted(Eval("totallessons"), Eval("completedlessons"), Eval("totalNumAvail"), Eval("totalNumCorrect"))%></td>
<td><%#FormatPercent(Eval("totalnumcorrect") / Eval("totalNumAvail"))%> <%-- (<%#Eval("totalnumcorrect")%> / <%#Eval("totalNumAvail")%>) --%></td>
<td><%#FormatPercent(Eval("completedlessons") / Eval("totallessons"))%> <%-- (<%#Eval("completedlessons")%> / <%#Eval("totallessons")%>) --%></td>
<td><%#Eval("lastaccessed")%></td>
</tr>
</ItemTemplate>
</asp:Repeater>
I can't figure it out but as soon as it hits some NULL data it refuses to move on to drawing the next elements.
You need to give a stack trace to be sure.
But I can see several issues:
DIV#0 errors inside FormatPercent
NULL errors.
Example Solution
(System.Convert.ToInt32 should convert DBNull/NULL to 0)
Or alter isCompleted to accept Object paramters and do your NULL / DBNull checking inside the function.
On slightly different approach that might be helpful would be to do your computations in your code behind rather than inline in the markup. Just easier to check for nulls etc. I almost always go down this path with anything other than a simple Eval() in my markup.
<td>
<%#GetCorrectPercent()%>
</td>
protected string GetCorrectPercent()
{
if(Eval("totalnumcorrect") == null || Eval("totalNumAvail") == null)
return "n/a";
return ((int)Eval("totalnumcorrect") / (int)Eval("totalNumAvail")).ToString();
}
Not sure all the formatting is correct here but this should get you going in a different direction. Eval() will work within the called methods so long as the caller is current performing a DataBind().
If I had to guess, I would say that your isCompleted function doesn't handle values of Nothing. This is a guess because the function hasn't been listed in your example.
I tend more towards the explicit. Forgive any minor mistakes in the code, I'm not able to test this.
If in your markup you swap out those evals for literals then in the code behind:
If you have a collection of MyClass.
In your page's init event
this.rptLessons.OnItemDataBound += rptLessons_DataBound...
In the load or where ever you choose
this.rptLessons.DataSource = CollectionOfMyClass;
this.rptLessons.DataBind();
Then in that itemDataBoundEvent
MyClass myClass = (MyClass)ri.DataItem;
Literal litFullname = FindControl(ri, "litFullName");
litFullName.Text = myClass.Fullname;
This way you can cater for nulls etc in a more controlled way than using eval.