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Introduction

OData is defined as "An open protocol to allow the creation and consumption of queryable and interoperable RESTful APIs in a simple and standard way" (odata.org). You can use OData with ASP.NET Boilerplate. The Abp.AspNetCore.OData NuGet package simplifies its usage.

Setup

Install NuGet Package

We must first install the Abp.AspNetCore.OData NuGet package to our Web.Core project:

Install-Package Abp.AspNetCore.OData

Set Module Dependency

We need to set a dependency on AbpAspNetCoreODataModule for our module. Example:

[DependsOn(typeof(AbpAspNetCoreODataModule))]
public class MyProjectWebCoreModule : AbpModule
{
    ...
}

See the module system to understand module dependencies.

Configure Your Entities

OData requires us to declare entities which can be used as OData resources. We must do this in the Startup class:

For asp net core 2.x

public class Startup
{
    public IServiceProvider ConfigureServices(IServiceCollection services)
    {
        ...

        services.AddOData();

        // Workaround: https://github.com/OData/WebApi/issues/1177
        services.AddMvcCore(options =>
        {
            foreach (var outputFormatter in options.OutputFormatters.OfType<ODataOutputFormatter>().Where(_ => _.SupportedMediaTypes.Count == 0))
            {
                outputFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/prs.odatatestxx-odata"));
            }
            foreach (var inputFormatter in options.InputFormatters.OfType<ODataInputFormatter>().Where(_ => _.SupportedMediaTypes.Count == 0))
            {
                inputFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/prs.odatatestxx-odata"));
            }
        });

        return services.AddAbp<MyProjectWebHostModule>(...);
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        app.UseAbp();

        ...

        app.UseOData(builder =>
        {
            builder.EntitySet<Person>("Persons").EntityType.Expand().Filter().OrderBy().Page();
        });

        // Return IQueryable from controllers
        app.UseUnitOfWork(options =>
        {
            options.Filter = httpContext =>
            {
                return httpContext.Request.Path.Value.StartsWith("/odata");
            };
        });

        app.UseMvc(routes =>
        {
            routes.MapODataServiceRoute(app);

            ...
        });
    }
}

For asp net core 3.x

public class Startup
{
    public IServiceProvider ConfigureServices(IServiceCollection services)
    {
        ...

        services.AddOData();

        // Workaround: https://github.com/OData/WebApi/issues/1177
        services.AddMvcCore(options =>
        {
            foreach (var outputFormatter in options.OutputFormatters.OfType<ODataOutputFormatter>().Where(_ => _.SupportedMediaTypes.Count == 0))
            {
                outputFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/prs.odatatestxx-odata"));
            }
            foreach (var inputFormatter in options.InputFormatters.OfType<ODataInputFormatter>().Where(_ => _.SupportedMediaTypes.Count == 0))
            {
                inputFormatter.SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/prs.odatatestxx-odata"));
            }
        });

        return services.AddAbp<MyProjectWebHostModule>(...);
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        app.UseAbp();
        // Return IQueryable from controllers
        app.UseUnitOfWork(options =>
        {
        	options.Filter = httpContext => httpContext.Request.Path.Value.StartsWith("/odata");
        });
        ...
            
		app.UseODataBatching();
        app.UseEndpoints(endpoints =>
        {
            ...
            var builder = new ODataConventionModelBuilder();
            builder.EntitySet<Person>("Persons").EntityType.Expand().Filter().OrderBy().Page();
            endpoints.MapODataRoute("odataPrefix", "odata",  builder.GetEdmModel());
            ...
        });        
        ...
    }
}

For asp net core 5.x and above

public class Startup
{
    public IServiceProvider ConfigureServices(IServiceCollection services)
    {
        ...
		services.AddMvc(/*...*/)
			.AddOData(opts =>
				{
					var builder = new ODataConventionModelBuilder();
					builder.EntitySet<Person>("Persons").EntityType.Expand().Filter().OrderBy().Page().Select();
					opts.AddRouteComponents("odata", builder.GetEdmModel());
				}
			);

        return services.AddAbp<MyProjectWebHostModule>(...);
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        app.UseAbp();
		
		// Return IQueryable from controllers
		app.UseUnitOfWork(options =>
		{
			options.Filter = httpContext => httpContext.Request.Path.Value.StartsWith("/odata");
		});
        ...
	}
}

Here, we got the ODataModelBuilder reference and set the Person entity. You can use EntitySet to add other entities in a similar way. See the OData documentation for more information on the builder.

Create Controllers

The Abp.AspNetCore.OData NuGet package includes the AbpODataEntityController base class (which extends standard ODataController) to create your controllers easier. An example to create an OData endpoint for the Person entity:

public class PersonsController : AbpODataEntityController<Person>, ITransientDependency 
{
    public PersonsController(IRepository<Person> repository)
        : base(repository)
    {
    }
}

It's that easy! All the methods of AbpODataEntityController are virtual. This means that you can override the Get, Post, Put, Patch, Delete and other actions and add your own logic.

Configuration

Abp.AspNetCore.OData calls the IRouteBuilder.MapODataServiceRoute method with the conventional configuration. If you need to, you can set Configuration.Modules.AbpAspNetCoreOData().MapAction to map OData routes yourself.

Examples

Here are some requests made to the controller defined above. Assume that the application works on http://localhost:21021. We will show some basic examples. Since OData is a standard protocol, you can easily find more advanced examples on the web.

Getting List of Entities

Getting all people.

Request

GET http://localhost:21021/odata/Persons

Response

{
  "@odata.context": "http://localhost:21021/odata/$metadata#Persons",
  "value": [
    {
      "Name": "Douglas Adams",
      "IsDeleted": false,
      "DeleterUserId": null,
      "DeletionTime": null,
      "LastModificationTime": null,
      "LastModifierUserId": null,
      "CreationTime": "2015-11-07T20:12:39.363+03:00",
      "CreatorUserId": null,
      "Id": 1
    },
    {
      "Name": "John Nash",
      "IsDeleted": false,
      "DeleterUserId": null,
      "DeletionTime": null,
      "LastModificationTime": null,
      "LastModifierUserId": null,
      "CreationTime": "2015-11-07T20:12:39.363+03:00",
      "CreatorUserId": null,
      "Id": 2
    }
  ]
}

Getting a Single Entity

Getting the person with Id = 2.

Request

GET http://localhost:21021/odata/Persons(2)

Response

{
  "@odata.context": "http://localhost:21021/odata/$metadata#Persons/$entity",
  "Name": "John Nash",
  "IsDeleted": false,
  "DeleterUserId": null,
  "DeletionTime": null,
  "LastModificationTime": null,
  "LastModifierUserId": null,
  "CreationTime": "2015-11-07T20:12:39.363+03:00",
  "CreatorUserId": null,
  "Id": 2
}

Getting a Single Entity With Navigation Properties

Getting the person with Id = 1 including his/her phone numbers.

Request

GET http://localhost:21021/odata/Persons(1)?$expand=Phones

Response

{
  "@odata.context": "http://localhost:21021/odata/$metadata#Persons/$entity",
  "Name": "Douglas Adams",
  "IsDeleted": false,
  "DeleterUserId": null,
  "DeletionTime": null,
  "LastModificationTime": null,
  "LastModifierUserId": null,
  "CreationTime": "2015-11-07T20:12:39.363+03:00",
  "CreatorUserId": null,
  "Id": 1,
  "Phones": [
    {
      "PersonId": 1,
      "Type": "Mobile",
      "Number": "4242424242",
      "CreationTime": "2015-11-07T20:12:39.363+03:00",
      "CreatorUserId": null,
      "Id": 1
    },
    {
      "PersonId": 1,
      "Type": "Mobile",
      "Number": "2424242424",
      "CreationTime": "2015-11-07T20:12:39.363+03:00",
      "CreatorUserId": null,
      "Id": 2
    }
  ]
}

Querying

Here's a more advanced query that includes filtering, sorting and getting the top 2 results.

Request

GET http://localhost:21021/odata/Persons?$filter=Name eq 'Douglas Adams'&$orderby=CreationTime&$top=2

Response

{
  "@odata.context": "http://localhost:21021/odata/$metadata#Persons",
  "value": [
    {
      "Name": "Douglas Adams",
      "IsDeleted": false,
      "DeleterUserId": null,
      "DeletionTime": null,
      "LastModificationTime": null,
      "LastModifierUserId": null,
      "CreationTime": "2015-11-07T20:12:39.363+03:00",
      "CreatorUserId": null,
      "Id": 1
    }
  ]
}

OData supports paging, sorting, filtering, projections and much more. See its own documentation for more information.

Creating a New Entity

In this example, we're creating a new person.

Request

POST http://localhost:21021/odata/Persons
{
    Name: "Galileo Galilei"
}

Here, the "Content-Type" header is "application/json".

Response

{
  "@odata.context": "http://localhost:21021/odata/$metadata#Persons/$entity",
  "Name": "Galileo Galilei",
  "IsDeleted": false,
  "DeleterUserId": null,
  "DeletionTime": null,
  "LastModificationTime": null,
  "LastModifierUserId": null,
  "CreationTime": "2016-01-12T20:36:04.1628263+02:00",
  "CreatorUserId": null,
  "Id": 4
}

If we get the list again, we can see the new person. We can also update or delete an existing entity since OData supports it.

Getting MetaData

We can get the metadata of entities, as shown in this example.

Request

GET http://localhost:21021/odata/$metadata

Response

<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="4.0" xmlns:edmx="http://docs.oasis-open.org/odata/ns/edmx">
    <edmx:DataServices>
        <Schema Namespace="AbpODataDemo.People" xmlns="http://docs.oasis-open.org/odata/ns/edm">

            <EntityType Name="Person">
                <Key>
                    <PropertyRef Name="Id" />
                </Key>
                <Property Name="Name" Type="Edm.String" Nullable="false" />
                <Property Name="IsDeleted" Type="Edm.Boolean" Nullable="false" />
                <Property Name="DeleterUserId" Type="Edm.Int64" />
                <Property Name="DeletionTime" Type="Edm.DateTimeOffset" />
                <Property Name="LastModificationTime" Type="Edm.DateTimeOffset" />
                <Property Name="LastModifierUserId" Type="Edm.Int64" />
                <Property Name="CreationTime" Type="Edm.DateTimeOffset" Nullable="false" />
                <Property Name="CreatorUserId" Type="Edm.Int64" />
                <Property Name="Id" Type="Edm.Int32" Nullable="false" />
                <NavigationProperty Name="Phones" Type="Collection(AbpODataDemo.People.Phone)" />
            </EntityType>

            <EntityType Name="Phone">
                <Key>
                    <PropertyRef Name="Id" />
                </Key>
                <Property Name="PersonId" Type="Edm.Int32" />
                <Property Name="Type" Type="AbpODataDemo.People.PhoneType" Nullable="false" />
                <Property Name="Number" Type="Edm.String" Nullable="false" />
                <Property Name="CreationTime" Type="Edm.DateTimeOffset" Nullable="false" />
                <Property Name="CreatorUserId" Type="Edm.Int64" />
                <Property Name="Id" Type="Edm.Int32" Nullable="false" />
                <NavigationProperty Name="Person" Type="AbpODataDemo.People.Person">
                    <ReferentialConstraint Property="PersonId" ReferencedProperty="Id" />
                </NavigationProperty>
            </EntityType>

            <EnumType Name="PhoneType">
                <Member Name="Unknown" Value="0" />
                <Member Name="Mobile" Value="1" />
                <Member Name="Home" Value="2" />
                <Member Name="Office" Value="3" />
            </EnumType>

        </Schema>
        <Schema Namespace="Default" xmlns="http://docs.oasis-open.org/odata/ns/edm">

            <EntityContainer Name="Container">
                <EntitySet Name="Persons" EntityType="AbpODataDemo.People.Person" />
            </EntityContainer>

        </Schema>
    </edmx:DataServices>
</edmx:Edmx>

Metadata is used to investigate the service.

Note: If you want to use ODataQueryOptions in the controller methods, you need to ignore validation for ODataQueryOptions and ODataQueryOptions<> as shown below;

Configuration.Validation.IgnoredTypes.AddIfNotContains(typeof(ODataQueryOptions)); 
Configuration.Validation.IgnoredTypes.AddIfNotContains(typeof(ODataQueryOptions<>));

Sample Project

You can get the source code of the sample project here: https://github.com/aspnetboilerplate/sample-odata