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ServiceStack CSV Format

Franck Quintana edited this page · 10 revisions

  1. Getting Started

    1. Creating your first project
      1. Create Service from scratch
    2. Your first webservice explained
    3. ServiceStack's new API Design
    4. Designing a REST-ful service with ServiceStack
    5. Example Projects Overview
    6. Learning Resources
  2. Reference

    1. Order of Operations
    2. The IoC container
    3. Configuration and AppSettings
    4. Metadata page
    5. Rest, SOAP & default endpoints
    6. SOAP support
    7. Routing
    8. Service return types
    9. Customize HTTP Responses
    10. Plugins
    11. Validation
    12. Error Handling
    13. Security
    14. Debugging
    15. JavaScript Client Library (ss-utils.js)
  3. Clients

    1. Overview
    2. C#/.NET client
    3. Add ServiceStack Reference
      1. C# Add Reference
      2. F# Add Reference
      3. VB.NET Add Reference
      4. Swift Add Reference
    4. Silverlight client
    5. JavaScript client
      1. Add TypeScript Reference
    6. Dart Client
    7. MQ Clients
  4. Formats

    1. Overview
    2. JSON/JSV and XML
    3. ServiceStack's new HTML5 Report Format
    4. ServiceStack's new CSV Format
    5. MessagePack Format
    6. ProtoBuf Format
  5. View Engines

    1. Razor & Markdown Razor
    2. Markdown Razor
  6. Hosts

    1. IIS
    2. Self-hosting
    3. Messaging
    4. Mono
  7. Security

    1. Authentication/authorization
    2. Sessions
    3. Restricting Services
  8. Advanced

    1. Configuration options
    2. Access HTTP specific features in services
    3. Logging
    4. Serialization/deserialization
    5. Request/response filters
    6. Filter attributes
    7. Concurrency Model
    8. Built-in caching options
    9. Built-in profiling
    10. Form Hijacking Prevention
    11. Auto-Mapping
    12. HTTP Utils
    13. Virtual File System
    14. Config API
    15. Physical Project Structure
    16. Modularizing Services
    17. ServiceStack Integration
    18. Embedded Native Desktop Apps
    19. Auto Batched Requests
  9. Server Events

    1. Overview
    2. JavaScript Client
    3. C# Server Events Client
    4. Redis Server Events
  10. Plugins

    1. Auto Query
    2. Server Sent Events
    3. Swagger API
    4. Postman
    5. Request logger
    6. Sitemaps
  11. Tests

    1. Testing
    2. HowTo write unit/integration tests
  12. ServiceStackVS

    1. Install ServiceStackVS
    2. Add ServiceStack Reference
    3. AngularJS App Template
    4. ReactJS App Template
  13. Other Languages

    1. FSharp
      1. Add ServiceStack Reference
    2. VB.NET
      1. Add ServiceStack Reference
    3. Swift
      1. Swift Add Reference
  14. Deployment

    1. Deploy Multiple Sites to single AWS Instance
      1. Simple Deployments to AWS with WebDeploy
    2. Advanced Deployments with OctopusDeploy
  15. Install 3rd Party Products

    1. Redis on Windows
    2. RabbitMQ on Windows
  16. Use Cases

    1. Single Page Apps
      1. HTML, CSS and JS Minifiers
    2. Azure
      1. Connecting to Azure Redis via SSL
    3. Logging
    4. Bundling and Minification
    5. NHibernate
  17. Performance

    1. Real world performance
  18. How To

    1. Sending stream to ServiceStack
    2. Setting UserAgent in ServiceStack JsonServiceClient
    3. ServiceStack adding to allowed file extensions
    4. Default web service page how to
  19. Future

    1. Roadmap
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ServiceStack's CSV Format

The CSV format is now a first-class supported format which means all your existing web services can automatically take advantage of the new format without any config or code changes. Just drop the latest ServiceStack.dlls (v1.77+) and you're good to go!

Importance of CSV

CSV is an important format for transferring, migrating and quickly visualizing data as all spreadsheets support viewing and editing CSV files directly whilst its supported by most RDBMS support exporting and importing data. Compared with other serialization formats, it provides a compact and efficient way to transfer large datasets in an easy to read text format.

Speed

The CSV Serializer used was developed using the same tech that makes ServiceStack's JSV and JSON serializers fast (i.e. no run-time reflection, static delegate caching, etc), which should make it the fastest CSV serializer available for .NET.

Downloadable Separately

The CsvSerializer is maintained in the ServiceStack.Text project which can be downloaded from NuGet at:

PM> Install-Package ServiceStack.Text

How to register your own custom format with ServiceStack

What makes the 'CSV' format different is its the first format added using the new extensions API. The complete code to register the CSV format is:

//Register the 'text/csv' content-type and serializers 
//(format is inferred from the last part of the content-type)

this.ContentTypes.Register(ContentType.Csv,
    CsvSerializer.SerializeToStream, CsvSerializer.DeserializeFromStream);

//Add a response filter to add a 'Content-Disposition' header so browsers treat it natively as a .csv file
this.ResponseFilters.Add((req, res, dto) =>
{
    if (req.ResponseContentType == ContentType.Csv)
    {
        res.AddHeader(HttpHeaders.ContentDisposition,
            string.Format("attachment;filename={0}.csv", req.OperationName));
    }
});

Note: ServiceStack already does this for you though it still serves a good example to show how you can plug-in your own custom format. If you wish, you can remove all custom formats with (inside AppHost.Configure()):

this.ContentTypes.ClearCustomFilters();

The ability to automatically to register another format and provide immediate value and added functionality to all your existing web services (without any code-changes or configuration) we believe is a testament to ServiceStack's clean design of using strongly-typed 'message-based' DTOs to let you develop clean, testable and re-usable web services. No code-gen or marshalling is required to bind to an abstract method signature, every request and calling convention maps naturally to your webservices DTOs.

Usage

The CSV format is effectively a first-class supported format so everything should work as expected, including being registered as an available format on ServiceStack's metadata index page:

And being able to preview the output of a service:

By default they are automatically available using ServiceStack's standard calling conventions, e.g:

REST Usage

CSV also works just as you would expect with user-defined REST-ful urls, i.e. you can append ?format=csv to specify the format in the url e.g:

This is how the above web service output looks when opened up in google docs

Alternative in following with the HTTP specification you can also specify content-type "text/csv" in the Accept header of your HttpClient, e.g:

var httpReq = (HttpWebRequest)WebRequest.Create("http://nortwind.servicestack.net/customers");
httpReq.Accept = "text/csv";
var csv = new StreamReader(httpReq.GetResponse().GetResponseStream()).ReadToEnd();

Limitations

As most readers familiar with the CSV format will know there are some inherent limitations with CSV-format namely it is a flat-structured tabular data format that really only supports serialization of a single resultset.

This limitation remains, although if you decorate your Response DTO with a [Csv(CsvBehavior.FirstEnumerable)] or standard .NET [DataContract]/[DataMember] attributes the CSV Serializer will change to use the following conventions:

  • If you only return one result in your DTO it will serialize that.
  • If you return multiple results it will pick the first IEnumerable<> property or if it doesn't exist picks the first property.
  • Non-enumerable results are treated like a single row.

Basically if you only return 1 result it should work as expected otherwise it will chose the best candidate based on the rules above.

The second major limitation is that it doesn't yet include a CSV Deserializer (currently on the TODO list), so while you can view the results in CSV format you can't post data to your web service in CSV and have it automatically deserialize for you. You can however still upload a CSV file and parse it manually yourself.

Features

Unlike most CSV serializers that can only serialize rows of primitive values, the CsvSerializer uses the JSV Format under the hood so even complex types will be serialized in fields in a easy to read format - no matter how deep its hierarchy.

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