$expand in OData V4

Question

*更新：能够遵循本教程，现在我得到的错误状态为：

"message": "No HTTP resource was found that matches the request URI 'http://localhost:0000/api/v1/Pets('dog')/Color'."
"message": "No routing convention was found to select an action for the OData path with template '~/entityset/key/unresolved'."

有什么想法吗？*

在尝试使用OData V4检索Pet查询中的Color时，我遇到了一个错误。我遇到了很多麻烦，理想情况下我会使用颜色扩展(例如localhost:0000/api/v1/Pets('dog'($expand=颜色(

我需要返回的JSON类似于：

[
{
"_Key": "1",
"animalname": "dog",
"furcolorname": "black,white",
"color": {
"_Key": "1",
"colorname": "black"
},
{
"_Key": "2",
"colorname": "white"
}
}
]

也许我走错了路，不管怎样，任何投入都值得赞赏！

如果我查询localhost:0000/api/v1/Pets('dog'(:

…
"Message": "Invalid column name 'Pet__Key'."     
…

如果我查询localhost:0000/api/v1/Pets('dog'($exand=颜色：

…
"The query specified in the URI is not valid. Could not find a property named 'Colors' on type 'PetShop.Odata.Models.Pet'."    
…

Pet.cs型号：

namespace PetShop.Odata.Models
{
[Table("pet")]
public class Pet
{
[Key]
public string _Key { get; set; }
public string AnimalName { get; set; }
[ForeignKey("Color")]
public string FurColorName { get; set; }
public virtual Color Color { get; set; }
public virtual ICollection<Color> Colors { get; set; }
}
}

Color.cs型号：

namespace PetShop.Odata.Models
{
[Table("color")]
public class Color
{
public Color()
{
new HashSet<Pet>();
}
[Key]
public string _Key { get; set; }
public string ColorName { get; set; }
}
}

宠物控制器.cs:

namespace PetShop.Odata.Controllers
{
[ApiVersion("1.0")]
[ODataRoutePrefix("Pets")]
[ApiControllerMetricReport]
public class PetsController : ODataController
{
private readonly MyContext context = new MyContext ();
[HttpGet]
[ODataRoute]
[EnableQuery]
[ResponseType(typeof(List<Pet>))]
public IHttpActionResult Get()
{
return Ok(context.Pets.AsQueryable());
}
[EnableQuery]
public IQueryable<Color> Get ([FromODataUri] string key)
{
return context.Pets.Where(m => m._Key == key).SelectMany(a => a.Colors);
}
protected override void Dispose(bool disposing)
{
context.Dispose();
base.Dispose(disposing);
}
}
}

ColorsController.cs:

namespace PetShop.Odata.Controllers
{
[ApiVersion("1.0")]
[ODataRoutePrefix("Colors")]
[ApiControllerMetricReport]
public class ColorsController : ODataController
{
private readonly MyContext context = new MyContext ();
[HttpGet]
[ODataRoute]
[EnableQuery]
[ResponseType(typeof(List<Color>))]
public IHttpActionResult Get()
{
return Ok(context.Colors.AsQueryable());
}
protected override void Dispose(bool disposing)
{
context.Dispose();
base.Dispose(disposing);
}
}
}

PetConfig.cs:

namespace PetShop.Odata.Configuration
{   public class PetModelConfiguration : IModelConfiguration
{
public void Apply(ODataModelBuilder builder, ApiVersion apiVersion)
{
builder.EntitySet<Pet>("Pets");
}
}
}

ColorConfig.cs:

namespace PetShop.Odata.Configuration
{   public class ColorModelConfiguration : IModelConfiguration
{
public void Apply(ODataModelBuilder builder, ApiVersion apiVersion)
{
builder.EntitySet<Color>("Colors");
}
}
}

MyContext.cs:

…
public DbSet<Pet> Pets { get; set; }
public DbSet<Color> Colors { get; set; }
…

Setup.cs:

…
public static HttpServer CreateHttpServer()
{
var httpConfig = new HttpConfiguration();
var webApiServer = new HttpServer(httpConfig);
httpConfig.AddApiVersioning(options => options.ReportApiVersions = true);
httpConfig.Formatters.JsonFormatter.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
var modelBuilder = new VersionedODataModelBuilder(httpConfig)
{
ModelBuilderFactory = () => new ODataConventionModelBuilder().EnableLowerCamelCase(),
ModelConfigurations =
{
new PetConfig(),
new ColorConfig()
},
};
var models = modelBuilder.GetEdmModels();
httpConfig.Count().Filter().OrderBy().Expand().Select().MaxTop(null);
…

Answer 1

假设您使用默认路由约定，PetsController.cs中的Get colors方法与预期的OData路由格式不匹配。

代替以下内容：

[EnableQuery]
public IQueryable<Color> Get ([FromODataUri] string key)
{
return context.Pets.Where(m => m._Key == key).SelectMany(a => a.Colors);
}

你应该试试：

[EnableQuery]
public IQueryable<Color> GetColors ([FromODataUri] string key)
{
return context.Pets.Where(m => m._Key == key).SelectMany(a => a.Colors);
}

这个定义将使OData路由：http://localhost:0000/api/v1/Pets('dog')/Colors

有关路由约定的详细信息，请参见https://learn.microsoft.com/en-us/odata/webapi/built-in-routing-conventions.

还有两种替代方法：

1. 为自定义导航属性注册不同的名称
2. 定义自定义OData函数