ReportItems collection references in a paginated report (Report Builder)
Applies to: 
Microsoft Report Builder (SSRS)
Power BI Report Builder
Report Designer in SQL Server Data Tools
The ReportItems built-in collection is the set of text boxes from report items such as rows of a data region or text boxes on the paginated report design surface. The ReportItems collection includes text boxes that are in the current scope of a page header, page footer, or report body. This collection is determined at run time by the report processor and the report renderer. The current scope changes as the report processor successively combines report data and the report item layout elements as the user views pages of a report. You can use the ReportItems built-in collection to produce dictionary-style page headers that show the first and last items on each page.
Note
You can create and modify paginated report definition (.rdl) files in Microsoft Report Builder, Power BI Report Builder, and in Report Designer in SQL Server Data Tools.
Use the ReportItems Value property
Items within the ReportItems collection have only one property: Value. The value for a ReportItems item can be used to display or calculate data from another field in the report. To access the value of the current text box, you can use the Visual Basic built-in global Me.Value or simply Value. In report functions such as First and aggregate functions, use the fully qualified syntax.
For example:
This expression, placed in a text box, displays the value of a ReportItem text box named
Textbox1:=ReportItems!Textbox1.ValueThis expression, placed in a ReportItem text box Color property, displays the text in black when the value is > 0; otherwise, the value is displayed in red:
=IIF(Me.Value > 0,"Black","Red")This expression, placed in a text box in the page header or page footer, displays the first value per page of the rendered report, for a text box named
LastName:=First(ReportItems("LastName").Value)
Dictionary-style page header expressions
You can create a page header to display the first customer on the page and the last customer on the page. Because a text box in the page header can only refer to the ReportItems built-in collection once in an expression, you need to add two text boxes to the page header: one for the first customer name (=First(ReportItems!textboxLastName.Value) and one for the last customer name (=Last(ReportItems!textboxLastName.Value).
In a page header or page footer section, only text boxes on the current page are available as a member of the ReportItems collection. For example, if ReportItems!textboxLastName.Value refers to a text box that only appears on the first page for a multipage data region, you see a value for the first page, but all other pages display #Error to show the expression couldn't be evaluated as written.
Scope for the ReportItems collection
As the report is processed, each text box in the report body or in a data region is evaluated in the context of its dataset, data region, and group associations. The scope for a reference to the ReportItems collection is the current scope or any point higher than the current scope.
For example, a text box in a row that is in a parent group must not contain an expression that refers to the name of a text box in a child group row. Such an expression doesn't resolve to a value in the report because the child row text box is out of scope. For more information, see Aggregate functions reference (Report Builder).