Web API and OData V4 CRUD and Actions Part 3

This article demonstrates how simple CRUD operations can be mapped to an OData service, how to map DateTimeOffset to DateTime types in the entity framework and also how to create OData actions for Entities and Entity Collections. This post is part 3 of the Web API and OData V4 series.

Part 1 Getting started with Web API and OData V4 Part 1.
Part 2 Web API and OData V4 Queries, Functions and Attribute Routing Part 2
Part 3 Web API and OData V4 CRUD and Actions Part 3
Part 4 Web API OData V4 Using enum with Functions and Entities Part 4
Part 5 Web API OData V4 Using Unity IoC, SQLite with EF6 and OData Model Aliasing Part 5
Part 6 Web API OData V4 Using Contained Models Part 6
Part 7 Web API OData V4 Using a Singleton Part 7
Part 8 Web API OData V4 Using an OData T4 generated client Part 8
Part 9 Web API OData V4 Caching Part 9
Part 10 Web API OData V4 Batching Part 10
Part 11 Web API OData V4 Keys, Composite Keys and Functions Part 11

Code: https://github.com/damienbod/WebAPIODataV4

OData CRUD

Before POST or PUT can be executed, the Database mapping needs to be changed. OData V4 only supports DateTimeOffset. The database uses DateTime. This needs a mapping.
In the ContactType entity class, change the DateTime property:

public static class ContactTypeExpressions
{
 public static readonly Expression<Func<ContactType, DateTime>> ModifiedDate = c => c.LastModifiedOnInternal;
}

public DateTimeOffset ModifiedDate
{
 get { return new DateTimeOffset(LastModifiedOnInternal); }
 set { LastModifiedOnInternal = value.DateTime; }
}

private DateTime LastModifiedOnInternal { get; set; }

Now that the Entity maps the DateTime to a DateTimeOffset, this needs to be added in the OnModelCreating method in the DomainModel.

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
  modelBuilder.Entity<ContactType>().Ignore(c => c.ModifiedDate);
  modelBuilder.Entity<ContactType>().Property(WebAppODataV4.Database.ContactType.ContactTypeExpressions.ModifiedDate).HasColumnName("ModifiedDate");
       

Create a HTTP POST method in the OData ContactTypeController

[ODataRoute()]
[HttpPost]
[EnableQuery(AllowedQueryOptions = AllowedQueryOptions.All)]
public IHttpActionResult Post(ContactType contactType)
{
  if (!ModelState.IsValid)
  {
    return BadRequest(ModelState);
  }

  _db.ContactType.AddOrUpdate(contactType);
  _db.SaveChanges();
  return Created(contactType);
}

Now a new ContactType entity can be created with a HTTP post:

This can then be validated in the database:

Now the PUT, PATCH and DELETE methods can be added. No Content is required per default.

HttpPut method or Update:
Note: The request header requires Prefer: return-content, otherwise the default no-content is returned.

[ODataRoute("({key})")]
[HttpPut]
[EnableQuery(AllowedQueryOptions = AllowedQueryOptions.All)]
public IHttpActionResult Put([FromODataUri] int key, ContactType contactType)
{
  if (!ModelState.IsValid)
  {
     return BadRequest(ModelState);
  }

  if (key != contactType.ContactTypeID)
  {
    return BadRequest();
  }

  _db.ContactType.AddOrUpdate(contactType);
  _db.SaveChanges();

  return Updated(contactType);
}

HttpDelete

[ODataRoute()]
[HttpDelete]
[EnableQuery(AllowedQueryOptions = AllowedQueryOptions.All)]
public IHttpActionResult Delete([FromODataUri] int key)
{
  var entityInDb = _db.ContactType.SingleOrDefault(t => t.ContactTypeID == key);
  _db.ContactType.Remove(entityInDb);
  _db.SaveChanges();

   return Content(HttpStatusCode.NoContent, "Deleted");
}

HttpPatch partial update
Note: The request header requires Prefer: return-content, otherwise the default no-content is returned.

[ODataRoute()]
[HttpPatch]
[EnableQuery(AllowedQueryOptions = AllowedQueryOptions.All)]
public IHttpActionResult Patch([FromODataUri] int key, Delta<ContactType> delta)
{
  if (!ModelState.IsValid)
  {
    return BadRequest(ModelState);
  }

  var contactType = _db.ContactType.Single(t => t.ContactTypeID == key);
  delta.Patch(contactType);
  _db.SaveChanges();
  return Updated (contactType);
}

OData Actions

Sometimes it is not so easy to do everything with CRUD operations, sometimes it needs extra logic to save etc. This can be done with OData actions.

In this example, an action is created and configured so that it can be called from the ContactType Entity or the ContactType Entity Collection. This code is added to the OData builder method.

EntitySetConfiguration<ContactType> contactType = builder.EntitySet<ContactType>("ContactType");
var actionY = contactType.EntityType.Action("ChangePersonStatus");
actionY.Parameter<string>("Level");
actionY.Returns<bool>();

var changePersonStatusAction = contactType.EntityType.Collection.Action("ChangePersonStatus");
changePersonStatusAction.Parameter<string>("Level");
changePersonStatusAction.Returns<bool>();

The action requires a level parameter and returns true or false.

This can then be added to the ContactTypeController:

[HttpPost]
[ODataRoute("Default.ChangePersonStatus")]
[EnableQuery(AllowedQueryOptions = AllowedQueryOptions.All)]
public IHttpActionResult ChangePersonStatus(ODataActionParameters parameters)
{
  if (ModelState.IsValid)
  {
   var level = parameters["Level"];
   // SAVE THIS TO THE DATABASE OR WHATEVER....
   }
   return Ok(true);
}

Now the action can be called:
For the Entity:
http://localhost:51902/odata/ContactType(5)/Default.ChangePersonStatus
For the Entity Collection:
http://localhost:51902/odata/ContactType/Default.ChangePersonStatus

This calls the action method with a Http Post. The Model is then validated and the parameters can be read and used.The action returns a bool.

Links:

http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api/odata-actions

http://msdn.microsoft.com/en-us/library/ff478141.aspx

http://www.odata.org/documentation/odata-version-2-0/uri-conventions/

SAMPLES: https://aspnet.codeplex.com/SourceControl/latest#Samples/WebApi/OData/v4/

https://aspnetwebstack.codeplex.com/SourceControl/latest

http://aspnetwebstack.codeplex.com/

http://www.asp.net/web-api/overview/releases/whats-new-in-aspnet-web-api-22

http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api/odata-routing-conventions

http://stackoverflow.com/questions/18233059/apicontroller-vs-odatacontroller-when-exposing-dtos

http://meyerweb.com/eric/tools/dencoder/

http://techbrij.com/jquery-datatables-asp-net-web-api-odata-service

http://www.asp.net/web-api/overview/odata-support-in-aspnet-web-api/supporting-odata-query-options

http://www.dotnetcurry.com/showarticle.aspx?ID=1008

Tags: OData, ODATA V4, TopHeaderMenu