In
one of my previous articles I explained how to use embedded code in SQL Server Reporting
Services. The possibility to add embedded code to a report, is a very powerfull feature
to add some custom functionality to your report.
But sometimes it might be necessary to add some custom functionality that is too complicated
for embedded code to handle efficiently, or you need to access the same function from
multiple reports, or you would like to write you code in C#...
In one of these cases you should develop a custom assembly to call from your report.
Let’s
start with a simple example and develop a function PercentageToColor() to return a
color based on a numeric value representing a percentage.
namespace MyAssembly
{
public class Colors
{
public string PercentageToColor(double percentage)
{
string returnValue
= string.Empty;
if (percentage
< 20)
{
returnValue
= "red";
}
else if (percentage
< 80)
{
returnValue
= "blue";
}
else
{
returnValue
= "green";
}
return returnValue;
}
}
}
Once
you’ve compiled your class you need to copy the resulting assembly to the directory
in which it is accessible from within your report:
· To
use it in the report designer, you need to copy it to:
C:\Program
Files\Microsoft Visual Studio 8\Common7\IDE\PrivateAssemblies
· To
make it available for reports that have been deployed to the report server, you need
to copy it to:
C:\Program
Files\Microsoft SQL Server\MSSQL.3\Reporting Services\ReportServer\bin
Before
you can access your custom assembly you have to reference the assembly: Open the report
properties (Menu: Report – Report Properties)
and select the References tab.
Browse
to your assembly and define a Class Name and an Instance Name. (The Class Name and
the Instance Name or only for non-static methods). Make sure to prefix your class
name with the assembly name.
Now
you can call the methods in your assembly from your report, using an expression:
· To
call a static method: =<AssemblyName>.<ClassName>.<StaticMethodName>
· To
call an instance method: =Code.<InstanceName>.<PublicMethodName>
So
in our example this would be: =Code.TestColor.PercentageToColor(Fields!Percentage.Value)
That's it! You've just created and called
a custom assembly from your report...
In one of my future articles I will
explain how to pass parameters to the class constructor and I will also tell something
about SSRS and .Net Permissions...
Davy
Knuysen
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