.NET Core开发日志之OData(Open Data Protocol)

2019-05-25 08:04:33丽君

创建Controller

本文实例中不考虑数据库的操作,故而使用hard code方式构建必要的模型对象。

public class BooksController : ODataController
{
  private static IList<Book> Books {get; set;}
  public BooksController()
  {
    Books = new List<Book>
    {
      new Book
      {
        Id = 1,
        ISBN = "111-0-321-56789-1",
        Title = "Calculus",
        Price = 66.6m,
        Address = new Address
        {
          City = "Shanghai",
          Street = "Beijin Xi Road"
        },
        Press = new Press
        {
          Id = 1,
          Name = "Shanghai Tongji",
          Category = Category.Book
        }
      },
      new Book
      {
        Id = 2,
        ISBN = "222-2-654-00000-2",
        Title = "Linear Algebra",
        Price = 53.2m,
        Address = new Address
        {
          City = "Shanghai",
          Street = "Beijin Dong Road"
        },
        Press = new Press
        {
          Id = 2,
          Name = "Shanghai Fudan",
          Category = Category.EBook
        }
      }      
    };  
  }

  [EnableQuery]
  public IActionResult Get()
  {
    return Ok(Books);
  }

  [EnableQuery]
  public IActionResult Get(int key)
  {
    return Ok(Books.FirstOrDefault(b => b.Id == key));
  }
}

EnableQuery特性在需要高级查询的场景时必须添加。

查询

加入Controller之后,访问https://localhost:5001/odata/Books地址,可得到所有Book数据。

{
  "@odata.context": "https://localhost:5001/odata/$metadata#Books",
  "value": [
    {
      "Id": 1,
      "ISBN": "111-0-321-56789-1",
      "Title": "Calculus",
      "Author": null,
      "Price": 66.6,
      "Address": {
        "City": "Shanghai",
        "Street": "Beijin Xi Road"
      }
    },
    {
      "Id": 2,
      "ISBN": "222-2-654-00000-2",
      "Title": "Linear Algebra",
      "Author": null,
      "Price": 53.2,
      "Address": {
        "City": "Shanghai",
        "Street": "Beijin Dong Road"
      }
    }
  ]
}

访问https://localhost:5001/odata/Books(1)地址,可得到key值为1的Book数据。

{
  "@odata.context": "https://localhost:5001/odata/$metadata#Books/$entity",
  "Id": 1,
  "ISBN": "111-0-321-56789-1",
  "Title": "Calculus",
  "Author": null,
  "Price": 66.6,
  "Address": {
    "City": "Shanghai",
    "Street": "Beijin Xi Road"
  }
}

高级查询

如果想要使用OData查询的高级功能,可以在注册终结点时额外加上相应的配置。

app.UseMvc(b =>
{
  b.Select().Expand().Filter().OrderBy().MaxTop(100).Count();
  b.MapODataServiceRoute("odata", "odata", GetEdmModel());
});

访问网址时加上所需的查询内容:
https://localhost:5001/odata/Books?$select=Id,Title

{
  "@odata.context": "https://localhost:5001/odata/$metadata#Books(Id,Title)",
  "value": [
    {
      "Id": 1,
      "Title": "Calculus"
    },
    {
      "Id": 2,
      "Title": "Linear Algebra"
    }
  ]
}