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How to Implement a Custom Report Source Resolver

This article explains how to create a custom report source resolver for the Telerik Reporting REST service. In this example, the resolver purpose will be to return a XmlReportSource with an XML report definition obtained from an SQL Server database.

How to implement a custom report source resolver:

  1. Create a class which implements the IReportSourceResolver interface. Its Resolve method will be called whenever the engine needs to create a ReportSource instance based on the parameter named report. The value of the report parameter will be initialized with the value of the Report property of the report viewer's ReportSource object.

    class CustomReportSourceResolver : IReportSourceResolver
    {
        public Telerik.Reporting.ReportSource Resolve(string reportId, OperationOrigin operationOrigin, IDictionary<string, object> currentParameterValues)
        {
            var cmdText = "SELECT Definition FROM Reports WHERE ID = @ReportId";
    
            var reportXml = string.Empty;
            using (var conn = new System.Data.SqlClient.SqlConnection(@"server=(local)\sqlexpress;database=REPORTS;integrated security=true;"))
            {
                var command = new System.Data.SqlClient.SqlCommand(cmdText, conn);
                command.Parameters.Add("@ReportId", System.Data.SqlDbType.Int);
                command.Parameters["@ReportId"].Value = reportId;
    
                try
                {
                    conn.Open();
                    reportXml = (string)command.ExecuteScalar();
                }
                catch (System.Exception ex)
                {
                    System.Diagnostics.Trace.WriteLine(ex.Message);
                }
            }
    
            if (string.IsNullOrEmpty(reportXml))
            {
                throw new System.Exception("Unable to load a report with the specified ID: " + reportId);
            }
    
            return new Telerik.Reporting.XmlReportSource { Xml = reportXml };
        }
    }
    
    Class CustomReportSourceResolver
        Implements IReportSourceResolver
        Public Function Resolve(reportId As String, operationOrigin As OperationOrigin, currentParameterValues As IDictionary(Of String, Object)) As Telerik.Reporting.ReportSource Implements Telerik.Reporting.Services.IReportSourceResolver.Resolve
            Dim cmdText = "SELECT Definition FROM Reports WHERE ID = @ReportId"
    
            Dim reportXml = ""
            Using conn = New System.Data.SqlClient.SqlConnection("server=(local)\sqlexpress;database=REPORTS;integrated security=true;")
                Dim command = New System.Data.SqlClient.SqlCommand(cmdText, conn)
                command.Parameters.Add("@ReportId", System.Data.SqlDbType.Int)
                command.Parameters("@ReportId").Value = reportId
    
                Try
                    conn.Open()
                    reportXml = DirectCast(command.ExecuteScalar(), String)
                Catch ex As System.Exception
                    System.Diagnostics.Trace.WriteLine(ex.Message)
                End Try
            End Using
    
            If String.IsNullOrEmpty(reportXml) Then
                Throw New System.Exception(Convert.ToString("Unable to load a report with the specified ID: ") & reportId)
            End If
    
            Dim reportSource As New Telerik.Reporting.XmlReportSource()
            reportSource.Xml = reportXml
            Return reportSource
        End Function
    End Class
    
  2. Find the ReportSourceResolver property in the ReportServiceConfiguration settings of the implementation of the ReportsControllerBase class, and set it to an instance of the custom report source resolver or to a chain of resolver instances including the custom one:

    public class CustomResolverReportsController : ReportsControllerBase
    {
        static ReportServiceConfiguration configurationInstance;
    
        static CustomResolverReportsController()
        {
            var resolver = new UriReportSourceResolver(HttpContext.Current.Server.MapPath("~/Reports"))
             .AddFallbackResolver(new TypeReportSourceResolver()
                 .AddFallbackResolver(new CustomReportSourceResolver()));
    
            configurationInstance = new ReportServiceConfiguration
            {
                HostAppId = "Application1",
                ReportSourceResolver = resolver,
                Storage = new Telerik.Reporting.Cache.File.FileStorage(),
            };
        }
    
        public CustomResolverReportsController()
        {
            this.ReportServiceConfiguration = configurationInstance;
        }
    }
    
    Public Class CustomResolverReportsController
        Inherits Telerik.Reporting.Services.WebApi.ReportsControllerBase
    
        Shared configurationInstance As ReportServiceConfiguration
    
        Shared Sub New()
            Dim resolver = New UriReportSourceResolver(HttpContext.Current.Server.MapPath("~/Reports")) _
                        .AddFallbackResolver(New TypeReportSourceResolver() _
                                             .AddFallbackResolver(New CustomReportSourceResolver()))
    
            Dim reportServiceConfiguration As New ReportServiceConfiguration()
            reportServiceConfiguration.HostAppId = "Application1"
            reportServiceConfiguration.ReportSourceResolver = resolver
            reportServiceConfiguration.Storage = New Telerik.Reporting.Cache.File.FileStorage()
            configurationInstance = reportServiceConfiguration
        End Sub
    
        Public Sub New()
            Me.ReportServiceConfiguration = configurationInstance
        End Sub
    End Class
    
  3. Request the report from the HTML5 Report Viewer on the client:

    <script type="text/javascript">
        $(document).ready(function () {
                $("#reportViewer1").telerik_ReportViewer({
                    serviceUrl: "api/reports/",
                    reportSource: { report: 1 }
            });
        });
    </script>
    

    where x.x.x.x is the version of the HTML5 ReportViewer/Telerik Reporting (e.g. 8.1.14.618).

  4. To create the database use the following script:

    USE [master]
    GO
    CREATE DATABASE [Reports]
    CONTAINMENT = NONE
    ON PRIMARY
    (NAME = N'Reports', FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL11.SQLEXPRESS\MSSQL\DATA\Reports.mdf', SIZE = 4096KB, MAXSIZE = UNLIMITED, FILEGROWTH = 1024KB)
    LOG ON
    (NAME = N'Reports_log', FILENAME = N'C:\Program Files\Microsoft SQL Server\MSSQL11.SQLEXPRESS\MSSQL\DATA\Reports_log.ldf', SIZE = 1024KB, MAXSIZE = 2048GB, FILEGROWTH = 10%)
    GO
    USE [Reports]
    GO
    CREATE TABLE [dbo].[Reports](
    [ID] [int] NOT NULL,
    [Definition] [nvarchar](max) NOT NULL
    ) ON [PRIMARY] TEXTIMAGE_ON [PRIMARY]
    GO
    
  5. To enter some data into the database you can manually edit the Reports table. XML report definitions can be obtained from the sample .trdx report files installed together with the product and are located in [Telerik_Reporting_Install_Dir]\Report Designer\Examples. In newer versions, all sample reports of the Standalone Report Designer are in TRDP format. You can use the Standalone Report Designer - File - Save As option to convert them to TRDX files.

How to implement and use custom IReportSourceResolver with fallback mechanism:

  1. Add to your IReportSourceResolver implementation a constructor with parameter IReportSourceResolver parentResolver. Then use the parentResolver if the custom report source resolving mechanism fails.

    class CustomReportSourceResolverWithFallBack : IReportSourceResolver
    {
        readonly IReportSourceResolver parentResolver;
    
        public CustomReportSourceResolverWithFallBack(IReportSourceResolver parentResolver)
        {
            this.parentResolver = parentResolver;
        }
    
        public ReportSource Resolve(string report, OperationOrigin operationOrigin, IDictionary<string, object> currentParameterValues)
        {
            ReportSource reportDocument = null;
            reportDocument = this.ResolveCustomReportSource(report, operationOrigin, currentParameterValues);
    
            if (null == reportDocument && null != this.parentResolver)
            {
                reportDocument = this.parentResolver.Resolve(report, operationOrigin, currentParameterValues);
            }
    
            return reportDocument;
        }
    
        public ReportSource ResolveCustomReportSource(string report, OperationOrigin operationOrigin, IDictionary<string, object> currentParameterValues)
        {
            //TODO implement custom report resolving mechanism
            return null;
        }
    }
    
    Class CustomReportSourceResolverWithFallBack
        Implements IReportSourceResolver
        ReadOnly parentResolver As IReportSourceResolver
    
        Public Sub New(parentResolver As IReportSourceResolver)
            Me.parentResolver = parentResolver
        End Sub
    
        Public Function Resolve(report As String, operationOrigin As OperationOrigin, currentParameterValues As IDictionary(Of String, Object)) As Telerik.Reporting.ReportSource Implements IReportSourceResolver.Resolve
            Dim reportDocument As IReportDocument = Nothing
            reportDocument = Me.ResolveCustomReportSource(report, operationOrigin, currentParameterValues)
    
            If reportDocument Is Nothing AndAlso Me.parentResolver IsNot Nothing Then
                reportDocument = Me.parentResolver.Resolve(report, operationOrigin, currentParameterValues)
            End If
    
            Return reportDocument
        End Function
    
        Public Function ResolveCustomReportSource(report As String, operationOrigin As OperationOrigin, currentParameterValues As IDictionary(Of String, Object)) As ReportSource
            'TODO implement custom report resolving mechanism
            Return Nothing
        End Function
    End Class
    
  2. Add to the ReportServiceConfiguration the IReportSourceResolver implementations in a chain. Thus the custom one will be executed first, if it fails the second one and so on.

    public class CustomResolverWithFallbackReportsController : ReportsControllerBase
    {
        static ReportServiceConfiguration configurationInstance;
    
        static CustomResolverWithFallbackReportsController()
        {
            var resolver = new CustomReportSourceResolverWithFallBack(new TypeReportSourceResolver()
                 .AddFallbackResolver(new UriReportSourceResolver(HttpContext.Current.Server.MapPath("~/Reports"))));
    
            configurationInstance = new ReportServiceConfiguration
            {
                HostAppId = "Application1",
                ReportSourceResolver = resolver,
                Storage = new Telerik.Reporting.Cache.File.FileStorage(),
            };
        }
    
        public CustomResolverWithFallbackReportsController()
        {
            this.ReportServiceConfiguration = configurationInstance;
        }
    }
    
    Public Class CustomResolverWithFallbackReportsController
        Inherits Telerik.Reporting.Services.WebApi.ReportsControllerBase
    
        Shared configurationInstance As ReportServiceConfiguration
    
        Shared Sub New()
            Dim resolver = New CustomReportSourceResolverWithFallBack(New TypeReportSourceResolver() _
                 .AddFallbackResolver(New UriReportSourceResolver(HttpContext.Current.Server.MapPath("~/Reports"))))
    
            Dim reportServiceConfiguration As New ReportServiceConfiguration()
            reportServiceConfiguration.HostAppId = "Application1"
            reportServiceConfiguration.ReportSourceResolver = resolver
            reportServiceConfiguration.Storage = New Telerik.Reporting.Cache.File.FileStorage()
            configurationInstance = reportServiceConfiguration
        End Sub
    
        Public Sub New()
            Me.ReportServiceConfiguration = configurationInstance
        End Sub
    End Class
    

    You can use for fallback the default IReportSourceResolver implementations:

    • TypeReportSourceResolver - Resolves IReportDocument from assembly qualified name

    • UriReportSourceResolver - Resolves IReportDocument from physical path to trdp or trdx file

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