Custom SQL Query Validation (WinForms)

• Aug 18, 2023
• 3 minutes to read

This tutorial describes how to implement validation for custom SQL queries.

Important

Unrestricted execution of custom queries enables your users to voluntarily modify a connected database. Avoid enabling this option unless you are certain about the expected results.

Custom SQL queries are validated before their execution. Although the default validation mechanism only allows custom queries containing SELECT statements (except for SELECT INTO clauses), it cannot be considered safe as it does not prevent the execution of potentially harmful requests. We recommend that you implement your own validation logic that permits only the execution of specific query types.

Do not reduce the default restrictions when implementing query validation.

To enable unrestricted execution of custom queries (for example, those containing DELETE, INSERT, PROCEDURE, and UPDATE statements), set the static SqlDataSource.DisableCustomQueryValidation property to true.

Validate Custom Queries in the Data Source Wizard

To implement custom query validation in the Data Source wizard, do the following:

1. Select the Report Designer’s XRDesignMdiController in the component tray.

   

2. In the Properties window, double-click the XRDesignMdiController.ValidateCustomSql event to handle it.

   

3. An event handler will be automatically added to the code of the Report Designer’s parent form. In the event handler, define your custom query validation logic.

   C#

   using DevExpress.XtraReports.UserDesigner;
   // ...
   private void reportDesigner1_ValidateCustomSql(object sender, ValidateSqlEventArgs e) {
       string sql = e.Sql;
       bool validationResult;
       // Insert your custom validation logic here.
       e.Valid = validationResult;
   }
   

   VB.NET

   Imports DevExpress.XtraReports.UserDesigner
   ' ...
   Private Sub reportDesigner1_ValidateCustomSql(ByVal sender As Object, ByVal e As ValidateSqlEventArgs)
       Dim sql As String = e.Sql
       Dim validationResult As Boolean
       ' Insert your custom validation logic here.
       e.Valid = validationResult
   End Sub
   

Validate Custom Queries in the Report Designer Preview

To validate custom queries in the Report Designer Preview, handle the static SqlDataSource.ValidateCustomSqlQueryGlobal event of the SqlDataSource class. This event occurs for all SQL data sources in the application.

You can validate custom queries in the Report Designer Preview for the specified SQL data source rather than globally. For this, handle the SqlDataSource.ValidateCustomSqlQuery event of the SqlDataSource instance.

C#

using DevExpress.DataAccess;
using DevExpress.DataAccess.Sql;
// ...

SqlDataSource.ValidateCustomSqlQueryGlobal += SqlDataSource_ValidateCustomSqlQueryGlobal;

void SqlDataSource_ValidateCustomSqlQueryGlobal(object sender, ValidateCustomSqlQueryEventArgs e) {
    CustomSqlQuery customQuery = e.CustomSqlQuery;
    bool validationResult;
    // Insert your custom validation logic here.
    e.Valid = validationResult;
}

VB.NET

Imports DevExpress.DataAccess
Imports DevExpress.DataAccess.Sql
' ...

AddHandler SqlDataSource.ValidateCustomSqlQueryGlobal, AddressOf SqlDataSource_ValidateCustomSqlQueryGlobal

Private Sub SqlDataSource_ValidateCustomSqlQueryGlobal(sender As Object, e As ValidateCustomSqlQueryEventArgs)
    Dim customQuery As CustomSqlQuery = e.CustomSqlQuery
    Dim validationResult As Boolean
    ' Insert your custom validation logic here.
    e.Valid = validationResult
End Sub

Note

To prevent end users from running custom queries in a Print Preview, set the SqlDataSource.AllowCustomSqlQueries property to false.