Dynamic ASP.NET Web API Controller - Part 1. Dynamic DTO

Introduction

In this article, I'll introduce how to make dynamic DTO.

We don't need to make new DTO every time when you add new stored procedures. I will show how to make DTO dynamically using ExpandoObject class.

Background

Making DTO is somewhat annoying to me. So I utilize ExpandoObject class to make DTO dynamically.

Using the code

GitHub ; https://github.com/thinkit-software/WebProjects/tree/master/src/Common

This is my data access layer. I write this sample with enterprise library 6. After fetching data from databse, we can make DTO like  javascript's object. This means we can add new property to C# class in runtime. That's so amazing!

namespace DavidJLee.DAL
{
    public class QueryExecutor
    {
        private readonly Database _db = default(Database);

        private static readonly Lazy<QueryExecutor> _instance = new Lazy<QueryExecutor>(() =>
        {
            return new QueryExecutor();
        });

        public static QueryExecutor Instance { get { return _instance.Value; } }

        public QueryExecutor()
        {
            DatabaseProviderFactory providerFactory = new DatabaseProviderFactory();
            DatabaseFactory.SetDatabaseProviderFactory(providerFactory, false);
            _db = DatabaseFactory.CreateDatabase();
        }

        public IEnumerable<dynamic> ExecuteStoredProcedure(string procName)
        {
            using (var command = _db.GetStoredProcCommand(procName))
            {
                var dataSet = _db.ExecuteDataSet(command);

                foreach (DataTable table in dataSet.Tables)
                {
                    foreach (DataRow row in table.Rows)
                    {
                        ExpandoObject dynamicDto = new ExpandoObject();

                        foreach (DataColumn column in table.Columns)
                        {
                            //With expandobject class, we can add new property like javascript's way.                           
                            ((IDictionary<String, Object>)dynamicDto).Add(column.ColumnName, row[column.ColumnName]);
                        }

                        yield return dynamicDto;
                    }                   
                }
            }
        }
    }
Colourised in 38ms

I use this method with ASP.NET Web API.

namespace DavidJLee.DynamicWebAPI.Controllers
{   
    public class ValuesController : ApiController
    {
        // GET api/values
        public IHttpActionResult Get()
        {
            return Json<IEnumerable<object>>(QueryExecutor.Instance.ExecuteStoredProcedure("usp_User_GetList"));
        }      
    }
}
Colourised in 7ms

I try to call this web API with fiddler.

Points of Interest

With this way, I developed dynamic Web API middle ware. Whenever I develop select command procedure, I don't need to add new controllers or actions. I just need to configure about new procedure (procedure name, parameter info etc).

History

1. Explanation of basic concept of dynamic web API with dynamic DTO (2014-08-23).