Multi-Value Report Parameters

轉自：https://docs.devexpress.com/XtraReports/9998/detailed-guide-to-devexpress-reporting/shape-report-data/use-report-parameters/multi-value-report-parameters

This document describes how to create a multi-value parameter and filter report data by the specified parameter values.

 

 

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See Specify Query Parameters for information on how to use multi-value parameters in an SQL query.

#Create a Multi-Value Parameter

Follow these steps to create a multi-value parameter at design time:

1. Create a report parameter and enable the Allow multiple values option (corresponds to the Parameter.MultiValue property).

2. Specify a list of predefined values for the parameter. See the following topics for more information:

   • Report Parameters with Predefined Static Values - to directly specify the list of values.
   • Report Parameters with Predefined Dynamic Values - to specify the storage that contains the list of values.

To create a multi-value report parameter in code, follow the steps below.

1. Create a StaticListLookUpSettings or DynamicListLookUpSettings class instance and configure it with a set of predefined parameter values.
2. Assign the newly created instance to the parameter's ValueSourceSettings property.
3. Enable the parameter's Parameter.MultiValue property. It allows the parameter to have more than one value.

NOTE

A complete sample project is available at https://github.com/DevExpress-Examples/how-to-assign-multiple-values-to-a-report-parameter-from-a-connected-data-source

• Form1.cs
• Form1.vb

using System;
using System.Windows.Forms;
using DevExpress.XtraReports.Parameters;
// ...

// Create a parameter and specify its name.
Parameter parameter1 = new Parameter();
parameter1.Name = "CategoryIDs";

// Specify other parameter properties.
parameter1.Type = typeof(System.Int32);
parameter1.MultiValue = true;
parameter1.Description = "Categories: ";

DynamicListLookUpSettings lookupSettings = new DynamicListLookUpSettings();
lookupSettings.DataSource = report.DataSource;
lookupSettings.DataMember = "Categories";
lookupSettings.DisplayMember = "CategoryName";
lookupSettings.ValueMember = "CategoryId";

parameter1.LookUpSettings = lookupSettings;
parameter1.Visible = true;
parameter1.SelectAllValues = true;

report.FilterString = "CategoryName in (?CategoryIDs)";

#Filter a Report by a Multi-Value Parameter

Use the Is any of operator in the report’s filter string:

 

 

To filter report data in code, specify the report’s FilterString property.

• C#
• VB.NET

using DevExpress.XtraReports.UI;
using DevExpress.XtraReports.Parameters;

// ...
// Create a parameter and specify its name. 
Parameter parameter1 = new Parameter(); 
parameter1.Name = "CategoryIDs"; 
Parameter1.Visible = true; 

//... 
// Filter report data  
report.FilterString = "CategoryName in (?CategoryIDs)";  

The filtered report is displayed after a user specifies parameter values.

#Pre-Select Parameter Values

Use one of the following methods to pre-select multiple parameter values when a report is first rendered.

• Assign an array of values to the Default Value (corresponds to Parameter.Value) property.

• Set the Expression property to an expression that evaluates to an array of values. You can use data source fields and other parameters in expressions.

• Enable the Select all values property to populate the parameter value with all items from its data source (static or dynamic).

   

   

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Disable the report's RequestParameters property to avoid the Waiting for parameter values message in Preview and display the report with pre-selected parameter values.

#Optional Multi-Value Parameter

You can leave the parameter unspecified and display all report data. A user optionally chooses parameter values to filter the report.

Do the following to make a multi-value parameter optional.

Configure the parameter as follows:

 

 

Property	Value
Allow null value	true
Default Value	Not specified
Expression	Not specified
Select all values	false

Disable the report's RequestParameters property.

Use the following report filter string:

?category Is Null or [Category ID] In (?category)

 

 

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You can also use the filter string shown above to filter report data at the data source level. See the Specify Query Parameters topic for more information.