Using Reporting Service API with HttpClient

Description

Sometimes it is sufficient to generate and download reports in certain formats without displaying them in a report viewer.

One way to achieve this is by creating a custom class that internally uses the HttpClient to perform the necessary requests to the Telerik Reporting REST Service in order to get the desired reports rendered on the server.

Solutions

.NET Framework

First, we will need to create the models for the response data. We may use Newtonsoft.Json.JsonProperty to annotate the properties:

public class ClientIDModel
{
    [Newtonsoft.Json.JsonProperty("clientId")]
    public string ClientId { get; set; }
}

public class ReportSourceModel
{
    [Newtonsoft.Json.JsonProperty("Report")]
    public string Report { get; set; }
    [Newtonsoft.Json.JsonProperty("ParameterValues")]
    public IDictionary<string, object> ParameterValues { get; set; }
}

public class InstanceIdModel
{
    [Newtonsoft.Json.JsonProperty("instanceId")]
    public string InstanceId { get; set; }
}

public class DocumentIdModel
{
    [Newtonsoft.Json.JsonProperty("documentId")]
    public string DocumentId { get; set; }
}

public class DocumentInfoModel
{
    [Newtonsoft.Json.JsonProperty("documentReady")]
    public bool DocumentReady { get; set; }

    [Newtonsoft.Json.JsonProperty("PageCount")]
    public int PageCount { get; set; }

    [Newtonsoft.Json.JsonProperty("DocumentMapAvailable")]
    public bool DocumentMapAvailable { get; set; }
}

public class ErrorModel
{
    [Newtonsoft.Json.JsonProperty("error")]
    public string Error { get; set; }

    [Newtonsoft.Json.JsonProperty("error_description")]
    public string Description { get; set; }
}

Then, we can create a ReportClient class that internally uses the HttpClient to perform all necessary requests to the server such as registering a new client, creating a new instance, etc.

public class ReportClient : IDisposable
{
    public string BaseAddress { get; set; }
    public HttpClient client;
    public string ClientId;

    public ReportClient(string uri)
    {
        this.client = new HttpClient();
        this.BaseAddress = uri;

        this.client.BaseAddress = new Uri(this.BaseAddress);
    }

    public void Dispose()
    {
        using (this.client) { }
    }

    public void RegisterClient()
    {
        var headers = new List<KeyValuePair<string, string>>();
        var content = new FormUrlEncodedContent(headers);

        var registerClientTask = this.client.PostAsync(this.BaseAddress + "/clients", content);
        var response = registerClientTask.Result;

        if (response.IsSuccessStatusCode)
        {
            var clientIdTask = response.Content.ReadAsAsync<ClientIDModel>();
            var clientId = clientIdTask.Result;
            this.ClientId = clientId.ClientId;
        }
        else
        {
            var error = response.Content.ReadAsAsync<ErrorModel>().Result;
            throw new Exception(error.Description);
        }
    }

    public string CreateInstance(string reportSource)
    {
        HttpContent content = new StringContent(reportSource, Encoding.UTF8, "application/json");

        string route = $"{this.BaseAddress}/clients/{this.ClientId}/instances";
        var instanceTask = this.client.PostAsync(route, content);

        InstanceIdModel instanceId = null;
        var response = instanceTask.Result;
        if (response.IsSuccessStatusCode)
        {
            instanceId = response.Content.ReadAsAsync<InstanceIdModel>().Result;
        }
        else
        {
            var error = response.Content.ReadAsAsync<ErrorModel>().Result;
            throw new Exception(error.Description);
        }

        return instanceId.InstanceId;
    }

    public string CreateDocument(string instanceId, string format, string deviceInfo = null, string useCache = "true")
    {
        string contentBody = $"{{ \"useCache\": {useCache}, \"format\": \"{format}\" }}";
        HttpContent content = new StringContent(contentBody, Encoding.UTF8, "application/json");

        string route = $"{this.BaseAddress}/clients/{this.ClientId}/instances/{instanceId}/documents";
        var documentTask = this.client.PostAsync(route, content);

        DocumentIdModel documentId = null;
        var response = documentTask.Result;
        if (response.IsSuccessStatusCode)
        {
            documentId = response.Content.ReadAsAsync<DocumentIdModel>().Result;
        }
        else
        {
            var error = response.Content.ReadAsAsync<ErrorModel>().Result;
            throw new Exception(error.Description);
        }

        return documentId.DocumentId;
    }

    public bool DocumentIsProcessing(string instanceId, string documentId)
    {
        string route = $"{this.BaseAddress}/clients/{this.ClientId}/instances/{instanceId}/documents/{documentId}/Info";

        var documentInfoTask = this.client.GetAsync(route);

        DocumentInfoModel documentInfo = null;
        var response = documentInfoTask.Result;
        if (response.IsSuccessStatusCode)
        {
            documentInfo = response.Content.ReadAsAsync<DocumentInfoModel>().Result;
        }
        else
        {
            var error = response.Content.ReadAsAsync<ErrorModel>().Result;
            throw new Exception(error.Description);
        }

        return !documentInfo.DocumentReady;
    }

    public byte[] GetDocument(string instanceId, string documentId)
    {
        string route = $"{this.BaseAddress}/clients/{this.ClientId}/instances/{instanceId}/documents/{documentId}";

        var getDocumentTask = this.client.GetAsync(route);

        byte[] documentBytes = null;
        var response = getDocumentTask.Result;
        if (response.IsSuccessStatusCode)
        {
            documentBytes = response.Content.ReadAsByteArrayAsync().Result;
        }
        else
        {
            var error = response.Content.ReadAsAsync<ErrorModel>().Result;
            throw new Exception(error.Description);
        }

        return documentBytes;
    }

    private static void EnsureSuccessStatusCode(HttpResponseMessage response)
    {
        if (!response.IsSuccessStatusCode)
        {
            throw
                new Exception(
                    response.ReasonPhrase +
                    Environment.NewLine +
                    response.RequestMessage.RequestUri);
        }
    }
}

In the end, the ReportClient may be used as follows for rendering the report:

// 1. Register client
ReportClient restServiceClient = InitializeReportClient(restServiceUrl);


// 2. Create Report Instance

ReportSourceModel reportSourceModel = new ReportSourceModel()
{
    Report = "Barcodes Report.trdp"
};

string reportSource = JsonConvert.SerializeObject(reportSourceModel);
string reportInstanceId = CreateReportInstance(restServiceClient, reportSource);


// 3. Create Document
string reportDocumentId = CreateDocument(restServiceClient, reportInstanceId, "PDF");


// 4. Get Document
byte[] result = GetDocument(restServiceClient, reportInstanceId, reportDocumentId);
File.WriteAllBytes("c:\\temp\\Barcodes Report.pdf", result);

.NET Core/ .NET

In .NET Core/.NET the models will be mostly the same expect that we may use the System.Text.Json namespace instead, for example:

public class ClientIDModel
{
    [System.Text.Json.Serialization.JsonPropertyName("clientId")]
    public string ClientId { get; set; }
}

public class ReportSourceModel
{
    [System.Text.Json.Serialization.JsonPropertyName("Report")]
    public string Report { get; set; }
    [System.Text.Json.Serialization.JsonPropertyName("ParameterValues")]
    public IDictionary<string, object> ParameterValues { get; set; }
}

public class InstanceIdModel
{
    [System.Text.Json.Serialization.JsonPropertyName("instanceId")]
    public string InstanceId { get; set; }
}

public class DocumentIdModel
{
    [System.Text.Json.Serialization.JsonPropertyName("documentId")]
    public string DocumentId { get; set; }
}

public class DocumentInfoModel
{
    [System.Text.Json.Serialization.JsonPropertyName("documentReady")]
    public bool DocumentReady { get; set; }

    [System.Text.Json.Serialization.JsonPropertyName("PageCount")]
    public int PageCount { get; set; }

    [System.Text.Json.Serialization.JsonPropertyName("DocumentMapAvailable")]
    public bool DocumentMapAvailable { get; set; }
}

public class ErrorModel
{
    [System.Text.Json.Serialization.JsonPropertyName("error")]
    public string Error { get; set; }

    [System.Text.Json.Serialization.JsonPropertyName("error_description")]
    public string Description { get; set; }
}

The ReadAsAsync method utilized in .NET Framework example above is a .NET Standard extension that is shared between ASP.NET Core and ASP.NET Web Api (via a NuGet library). However, it uses JSON.NET to do the deserialization, and as of .NET Core 3.0, ASP.NET Core now uses System.Text.Json instead. As such, this library (and the extension it contains) is not included in the .NET Core 3.0+ framework because doing so would require including the JSON.NET library in addition to System.Text.Json. Thus, instead of adding the Microsoft.AspNet.WebApi.Client (and Newtonsoft.Json along with it), we can implement the extension method ourselves using:
```
public static class HttpContentExtensions
{
    public static async Task<T> ReadAsAsync<T>(this HttpContent content) =>
        await System.Text.Json.JsonSerializer.DeserializeAsync<T>(await content.ReadAsStreamAsync());
}
```

The ReportClient class will be mostly the same as in the .NET Framework with the addition of the async/await syntax.

public class ReportClient : IDisposable
{
    public string BaseAddress { get; set; }
    public HttpClient client;
    public string ClientId;

    public ReportClient(string uri)
    {
        this.client = HttpClientFactory.Create();
        this.BaseAddress = uri;

        this.client.BaseAddress = new Uri(this.BaseAddress);
    }

    public void Dispose()
    {
        using (this.client) { }
    }

    public async Task RegisterClient()
    {
        var headers = new List<KeyValuePair<string, string>>();
        var content = new FormUrlEncodedContent(headers);

        var response = await this.client.PostAsync(this.BaseAddress + "/clients", content);

        if (response.IsSuccessStatusCode)
        {
            var clientIdTask = await response.Content.ReadAsAsync<ClientIDModel>();
            this.ClientId = clientIdTask.ClientId;
        }
        else
        {
            var error = await response.Content.ReadAsAsync<ErrorModel>();
            throw new Exception(error.Description);
        }
    }

    public async Task<string> CreateInstance(string reportSource)
    {
        HttpContent content = new StringContent(reportSource, Encoding.UTF8, "application/json");

        string route = $"{this.BaseAddress}/clients/{this.ClientId}/instances";
        var response = await this.client.PostAsync(route, content);

        InstanceIdModel instanceId = null;
        if (response.IsSuccessStatusCode)
        {
            instanceId = await response.Content.ReadAsAsync<InstanceIdModel>();
        }
        else
        {
            var error = await response.Content.ReadAsAsync<ErrorModel>();
            throw new Exception(error.Description);
        }

        return instanceId.InstanceId;
    }

    public async Task<string> CreateDocument(string instanceId, string format, string deviceInfo = null, string useCache = "true")
    {
        string contentBody = $"{{ \"useCache\": {useCache}, \"format\": \"{format}\" }}";
        HttpContent content = new StringContent(contentBody, Encoding.UTF8, "application/json");

        string route = $"{this.BaseAddress}/clients/{this.ClientId}/instances/{instanceId}/documents";
        var response = await this.client.PostAsync(route, content);

        DocumentIdModel documentId = null;
        if (response.IsSuccessStatusCode)
        {
            documentId = await response.Content.ReadAsAsync<DocumentIdModel>();
        }
        else
        {
            var error = await response.Content.ReadAsAsync<ErrorModel>();
            throw new Exception(error.Description);
        }

        return documentId.DocumentId;
    }

    public async Task<bool> DocumentIsProcessing(string instanceId, string documentId)
    {
        string route = $"{this.BaseAddress}/clients/{this.ClientId}/instances/{instanceId}/documents/{documentId}/Info";

        var response = await this.client.GetAsync(route);

        DocumentInfoModel documentInfo = null;
        if (response.IsSuccessStatusCode)
        {
            documentInfo = await response.Content.ReadAsAsync<DocumentInfoModel>();
        }
        else
        {
            var error = await response.Content.ReadAsAsync<ErrorModel>();
            throw new Exception(error.Description);
        }

        return !documentInfo.DocumentReady;
    }

    public async Task<byte[]> GetDocument(string instanceId, string documentId)
    {
        string route = $"{this.BaseAddress}/clients/{this.ClientId}/instances/{instanceId}/documents/{documentId}";

        var response = await this.client.GetAsync(route);
        byte[] documentBytes;

        if (response.IsSuccessStatusCode)
        {
            documentBytes = await response.Content.ReadAsByteArrayAsync();
        }
        else
        {
            var error = await response.Content.ReadAsAsync<ErrorModel>();
            throw new Exception(error.Description);
        }

        return documentBytes;
    }

    private static void EnsureSuccessStatusCode(HttpResponseMessage response)
    {
        if (!response.IsSuccessStatusCode)
        {
            throw
                new Exception(
                    response.ReasonPhrase +
                    Environment.NewLine +
                    response.RequestMessage.RequestUri);
        }
    }
}

In the end, executing the code to render the report may look as follows:

static async Task ExportReportFromServiceAsync(string reportName, string format, string baseUrl)
{
    // 1. Register client
    ReportClient reportClient = new ReportClient(baseUrl);
    await reportClient.RegisterClient();


    // 2. Create Report Instance
    ReportSourceModel reportSourceModel = new ReportSourceModel()
    {
        Report = reportName
    };

    string reportSource = System.Text.Json.JsonSerializer.Serialize(reportSourceModel);
    string reportInstanceId = await reportClient.CreateInstance(reportSource);


    // 3. Create Document
    string reportDocumentId = await reportClient.CreateDocument(reportInstanceId, format);

    bool documentProcessing;
    do
    {
        Thread.Sleep(500);// wait before next Info request
        documentProcessing = await reportClient.DocumentIsProcessing(reportInstanceId, reportDocumentId);
    } while (documentProcessing);

    // 4. Get Document
    byte[] result = await reportClient.GetDocument(reportInstanceId, reportDocumentId);
    File.WriteAllBytes($"C:\\temp\\{reportName}.{format.ToLower()}", result);
}

Sample Project

Sample Project

Using Reporting Service API with HttpClient

Environment

Description

Solutions

.NET Framework

.NET Core/ .NET

Sample Project

See Also

Getting Started

Support Resources

Community