OdataToEntity

OData .net core

This library provides a simple approach to creating OData service from ORM data context. This translates the OData query into an expression tree and passes it to the ORM framework. Supported ORM: Entity Framework 6, Entity Framework Core, Linq2Db

Example Asp.Net Core OData service in \sln\OdataToEntityCore.Asp.sln
client Microsoft.OData.Client - test\OdataToEntity.Test.Asp\OdataToEntity.Test.AspClient
server Asp .net core - test\OdataToEntity.Test.Asp\OdataToEntity.Test.AspServer
server Asp mvc .net core - test\OdataToEntity.Test.Asp\OdataToEntity.Test.AspMvcServer

Script create Sql Server database \test\OdataToEntity.Test.EfCore.SqlServer\script.sql
Script create PostgreSql database \test\OdataToEntity.Test.EfCore.PostgreSql\script.sql

public sealed class OrderContext : DbContext
{
    public DbSet<Customer> Customers { get; set; }
    public DbSet<Order> Orders { get; set; }

    public IEnumerable<Order> GetOrders(int? id, String name, OrderStatus? status) => throw new NotImplementedException();
}

Build OData EdmModel

Buid from entity classes marked data annotation attribute, the general case for all providers

//Create adapter data access, where OrderContext your DbContext
var dataAdapter = new OeEfCoreDataAdapter<Model.OrderContext>();
//Build OData Edm Model
EdmModel edmModel = dataAdapter.BuildEdmModel();

Build from the Entity Framework Core where the data context uses the "Fluent API" (without using attributes)

//Create adapter data access, where OrderContext your DbContext
var dataAdapter = new OeEfCoreDataAdapter<Model.OrderContext>();
//Build OData Edm Model
EdmModel edmModel = dataAdapter.BuildEdmModelFromEfCoreModel();

Build from the Entity Framework 6 where the data context uses the "Fluent API" (without using attributes)

//Create adapter data access, where OrderEf6Context your DbContext
var dataAdapter = new OeEf6DataAdapter<OrderEf6Context>();
//Build OData Edm Model
EdmModel edmModel = dataAdapter.BuildEdmModelFromEf6Model();

Sample OData query

For use odata.nextLink, the next link of a collection with partial results set property PageSize class OeParser
For use to-many navigation property odata.nextLink, the next link of a collection with results set property NavigationNextLink class OeParser

//Create adapter data access, where OrderContext your DbContext
var dataAdapter = new OeEfCoreDataAdapter<Model.OrderContext>();
//Create query parser
var parser = new OeParser(new Uri("http://dummy"), dataAdapter, dataAdapter.BuildEdmModel())
{
  NavigationNextLink = true,
  PageSize = 2
};
//Query
var uri = new Uri("http://dummy/Orders?$select=Name");
//The result of the query
var response = new MemoryStream();
//Execute query
await parser.ExecuteGetAsync(uri, OeRequestHeaders.JsonDefault, response, CancellationToken.None);

Sample OData batch request

string batch = @"
--batch_6263d2a1-1ddc-4b02-a1c1-7031cfa93691
Content-Type: multipart/mixed; boundary=changeset_e9a0e344-4133-4677-9be8-1d0006e40bb6

--changeset_e9a0e344-4133-4677-9be8-1d0006e40bb6
Content-Type: application/http
Content-Transfer-Encoding: binary
Content-ID: 1

POST http://dummy/Customers HTTP/1.1
OData-Version: 4.0
OData-MaxVersion: 4.0
Content-Type: application/json;odata.metadata=minimal
Accept: application/json;odata.metadata=minimal
Accept-Charset: UTF-8
User-Agent: Microsoft ADO.NET Data Services

{""@odata.type"":""#OdataToEntity.Test.Model.Customer"",""Address"":""Moscow"",""Id"":1,""Name"":""Ivan"",""[email protected]"":""#OdataToEntity.Test.Model.Sex"",""Sex"":""Male""}

--changeset_e9a0e344-4133-4677-9be8-1d0006e40bb6--
--batch_6263d2a1-1ddc-4b02-a1c1-7031cfa93691--
";

//Create adapter data access, where OrderContext your DbContext
var dataAdapter = new OeEfCoreDataAdapter<Model.OrderContext>();
//Create query parser
var parser = new OeParser(new Uri("http://dummy"), dataAdapter, dataAdapter.BuildEdmModel());
//Serialized entities in JSON UTF8 format
var request = new MemoryStream(System.Text.Encoding.UTF8.GetBytes(batch));
//The result of the query
var response = new MemoryStream();
//Execute query
await parser.ExecuteBatchAsync(request, response, CancellationToken.None);

Sample OData stored procedure

//Create adapter data access, where OrderContext your DbContext
var dataAdapter = new OeEfCoreDataAdapter<Model.OrderContext>();
//Create query parser
var parser = new OeParser(new Uri("http://dummy"), dataAdapter, dataAdapter.BuildEdmModel());
//The result of the stored procedure
var response = new MemoryStream();
//Execute sored procedure
await parser.ExecuteGetAsync(new Uri("http://dummy/GetOrders(name='Order 1',id=1,status=null)"), OeRequestHeaders.JsonDefault, response, CancellationToken.None);

Server-Driven Paging

To use responses that include only a partial set of the items identified by the request indicate maximum page size through the invoke method OeRequestHeaders.SetMaxPageSize(int maxPageSize). The service serializes the returned continuation token into the $skiptoken query option and returns it as part of the next link to the client. If request returns result set sorted by nullable property, should set OeDataAdapter.IsDatabaseNullHighestValue (SQLite, MySql, Sql Server set false, for PostgreSql, Oracle set true).

//Create adapter data access, where OrderContext your DbContext
var dataAdapter = new OeEfCoreDataAdapter<Model.OrderContext>(Model.OrderContext.CreateOptions())
{
  IsDatabaseNullHighestValue = true //PostgreSql
};
//Create query parser
var parser = new OeParser(new Uri("http://dummy"), dataAdapter, dataAdapter.BuildEdmModel());
//Query
var uri = new Uri("http://dummy/Orders?$select=Name&$orderby=Date");
//Set max page size
OeRequestHeaders requestHeaders = OeRequestHeaders.JsonDefault.SetMaxPageSize(10);
//The result of the query
var response = new MemoryStream();
//Execute query
await parser.ExecuteGetAsync(uri, requestHeaders, response, CancellationToken.None);

To use server side paging in expanded to-many navigation properties, should invoke method OeRequestHeaders.SetNavigationNextLink(true)

//Query
var uri = new Uri("http://dummy/Orders?$expand=Items");
//Set max page size,  to-many navigation properties
OeRequestHeaders requestHeaders = OeRequestHeaders.JsonDefault.SetMaxPageSize(10).SetNavigationNextLink(true);
//The result of the query
var response = new MemoryStream();
//Execute query
await parser.ExecuteGetAsync(uri, requestHeaders, response, CancellationToken.None);

Data context pooling

For use pooling (DbContextPool) in Entity Framework Core create instance OeEfCoreDataAdapter use constructor with DbContextOptions parameter.

//Create adapter data access, where OrderContext your DbContext
var dataAdapter = new OeEfCoreDataAdapter<Model.OrderContext>(Model.OrderContext.CreateOptions());