How to assign data in telerik report dynamically from c#?

Question

I have designed the report trdp file using the designer and added web service as data source. My plan is, when the report will be requested, instead of the web source, I want to pull the data using linq and want to inject that data in the report data source and want to pass it through the report processor. What I have done is: ``

        var rng = new Random();
        var datas = Enumerable.Range(1, 100).Select(index => new WeatherForecast
            {
                Category = Summaries[rng.Next(Summaries.Length)],
                Date = DateTime.Now.AddDays(index),
                TemperatureC = 1
            }).ToList();

        DataTable dataTable = Newtonsoft.Json.JsonConvert.DeserializeObject<DataTable>(Newtonsoft.Json.JsonConvert.SerializeObject(datas));
        Telerik.Reporting.Report report = null;
        using (var sourceStream = System.IO.File.OpenRead("Reports\\DemoReport.trdp"))
        {
            var reportPackager = new ReportPackager();
            report = (Report)reportPackager.UnpackageDocument(sourceStream);
            var dtsrc = new ObjectDataSource();
            dtsrc.DataSource = dataTable;
            report.DataSource = dtsrc;
        }
        

        Telerik.Reporting.Processing.ReportProcessor reportProcessor = new Telerik.Reporting.Processing.ReportProcessor();
        System.Collections.Hashtable deviceInfo = new System.Collections.Hashtable();
        Telerik.Reporting.Processing.RenderingResult result = reportProcessor.RenderReport("PDF", report, deviceInfo);

        var fileName = "adreport.pdf";
        using (FileStream fs = new FileStream(fileName, FileMode.Create))
        {
            fs.Write(result.DocumentBytes, 0, result.DocumentBytes.Length);
        }
        return Ok();

``

This generates the report but instead of a few pages, the generated pdf report contains a few hundreds of page with the same data repeatedly which is unusual. Can anyone explain why this is happening.

Answer 1

I am going to answer this question with as details as possible. For telerik reporting with angular and dynamically data assignment from backend code,follow the steps:-

1. Design the report template from Report designer
2. Place the templace in c# folter
3. Include report viewer in angular project
4. When report viewer will request for the report, handle it using the CustomReportResolver Sample code is provided below.

Angular

<tr-viewer #viewer1 
    [containerStyle]="viewerContainerStyle"
    [serviceUrl]="'https://localhost:5001/api/reports/'"
    [reportSource]="{
        report: 'DemoListReport.trdp',
        parameters:
        {

        }
    }"
    [viewMode]="'INTERACTIVE'"
    [scaleMode]="'SPECIFIC'"
    [scale]="1.0"
    [ready]="ready"
    [viewerToolTipOpening]="viewerToolTipOpening"
    [enableAccessibility]="false">
</tr-viewer>
<button (click)="viewer1.refreshReport()">Refresh</button>
<button (click)="viewer1.commands.print.exec()">Print</button>

.NET Core 3.1
Startup.cs

 services.TryAddScoped<IReportSourceResolver, CustomReportResolver>();
            // Configure dependencies for ReportsController.
            services.TryAddSingleton<IReportServiceConfiguration>(sp =>
                new ReportServiceConfiguration
                {
                    // The default ReportingEngineConfiguration will be initialized from appsettings.json or appsettings.{EnvironmentName}.json:
                        ReportingEngineConfiguration = sp.GetService<IConfiguration>(),
                        // In case the ReportingEngineConfiguration needs to be loaded from a specific configuration file, use the approach below:
                        // ReportingEngineConfiguration = ResolveSpecificReportingConfiguration(sp.GetService<IHostingEnvironment>()),
                        HostAppId = "Html5DemoAppCore",
                        Storage = new Telerik.Reporting.Cache.File.FileStorage(),
                        ReportSourceResolver = new CustomReportResolver()
                });

CustomReportResolver.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Telerik.Reporting;
using Telerik.Reporting.Services;
using Telerik.Reporting.Services.Engine;

namespace MyProject.API.Controllers
{
    public class CustomReportResolver: IReportSourceResolver
    {
        private static readonly string[] Summaries = new[]
        {
            "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
        };
        

        public ReportSource Resolve(string report, OperationOrigin operationOrigin, IDictionary<string, object> currentParameterValues)
        {
            //data
            var rng = new Random();
            var datas = Enumerable.Range(1, 500).Select(index => new WeatherForecast
            {
                Category = Summaries[rng.Next(Summaries.Length)],
                Date = DateTime.Now.AddDays(index),
                TemperatureC = 1
            }).ToList();
            
            

            var reportPackager = new ReportPackager();
            Report reportt = null;
            using (var sourceStream = System.IO.File.OpenRead($"Reports\\{report}"))
            {
                reportt = (Report)reportPackager.UnpackageDocument(sourceStream);
            }

            DetailSection detail = (DetailSection)reportt.Items["detailSection1"];
            Table table = (Table)detail.Items["table1"];
            table.DataSource = datas.Take(5);


            Graph graph = (Graph)detail.Items["graph1"];
            graph.DataSource = datas;


            InstanceReportSource instanceReportSource = new InstanceReportSource();
            instanceReportSource.ReportDocument = reportt;

            return instanceReportSource;
        }
    }
}

Here datas will pass your data to the report. Hopefully this will help others later.

Answer 2

Sounds like you are setting your data source incorrectly (more than once, for example firstly programmatically on report level and secondly on data item level somewhere in the report definition (DemoReport.trdp)) and you receive a cartesian product.