To add embedded code to a report, use the Code page of the Report Properties dialog box. The code block you create can contain multiple methods. Methods in embedded code must be written in Microsoft Visual Basic and must be instance-based. The report processor automatically adds references for the System.Convert and System.Math namespaces. Use the References page of the Report Properties dialog box to add additional assembly references. For more information, see How to: Add Code to a Report (Reporting Services) and How to: Add an Assembly Reference to a Report (Reporting Services).
Methods in embedded code are available through a globally defined Code member. You access these by referring to the Code member and the method name. The following example calls the method ToUSD, which converts the value in the StandardCost field to a dollar value:
=Code.ToUSD(Fields!StandardCost.Value)
To reference built-in collections in your custom code, include a reference to the built-in Report object:
=Report.Parameters!Param1.Value
The following examples show how to define some custom constants and variables.
Public Const MyNote = "Authored by Bob"
Public Const NCopies As Int32 = 2
Public Dim MyVersion As String = "123.456"
Public Dim MyDoubleVersion As Double = 123.456
Although custom constants do not appear in the Constants category in the Expression dialog box (which only displays built-in constants), you can add references to them from any expression, as shown in the following examples. In an expression, a custom constant is treated as a Variant.
=Code.MyNote
=Code.NCopies
=Code.MyVersion
=Code.MyDoubleVersion
The following example includes both the code reference and the code implementation of the function FixSpelling, which substitutes the text "Bicycle" for all occurrences of the text "Bike" in the SubCategory field.
=Code.FixSpelling(Fields!SubCategory.Value)
The following code, when embedded in a report definition code block, shows an implementation of the FixSpelling method. This example shows you how to use a fully qualified reference to the Microsoft .NET Framework StringBuilder class.
Public Function FixSpelling(ByVal s As String) As String
Dim strBuilder As New System.Text.StringBuilder(s)
If s.Contains("Bike") Then
strBuilder.Replace("Bike", "Bicycle")
Return strBuilder.ToString()
Else : Return s
End If
End Function
For more information about built-in object collections and initialization, see Using Global Collections in Expressions and Initializing Custom Assembly Objects.
Examples of Referencing Parameters from Custom Code
You can reference the global parameters collection via custom code in a Code block of the report definition or in a custom assembly that you provide. The parameters collection is read-only and has no public iterators. You cannot use a Visual Basic For Each construct to step through the collection. You need to know the name of the parameter defined in the report definition before you can reference it in your code. You can, however, iterate through all the values of a multivalue parameter. For more information, see Using Custom Code References in Expressions (Reporting Services).
The following table includes examples of referencing the built-in collection Parameters from custom code:
|
Description
|
Reference in Expression
|
Custom Code definition
|
|---|
|
Passing an entire global parameter collection to custom code.
This function returns the value of a specific report parameter MyParameter.
|
=Code.DisplayAParameterValue(Parameters)
|
Public Function DisplayAParameterValue(
ByVal parameters as Parameters) as Object
Return parameters("MyParameter").Value
End Function
|
|
Passing an individual parameter to custom code.
This example returns the value of the parameter passed in. If the parameter is a multivalue parameter, the return string is a concatenation of all the values.
|
=Code.ShowParametersValues(Parameters!DayOfTheWeek)
|
Public Function ShowParameterValues(ByVal parameter as Parameter)
as String
Dim s as String
If parameter.IsMultiValue then
s = "Multivalue: "
For i as integer = 0 to parameter.Count-1
s = s + CStr(parameter.Value(i)) + " "
Next
Else
s = "Single value: " + CStr(parameter.Value)
End If
Return s
End Function |