在 dotnet 核心中创建动态 EDM 模型

Question

我已经在https://github.com/OData/ODataSamples/tree/master/WebApi/v4/DynamicEdmModelCreation看到了动态 Odata 路由和模型生成的示例。

我需要同样的点网核心，但由于 Asp.net 和 Asp.net 核心在类/路由等方面有所不同。我无法将此代码转换为点网核心。

有人可以提供一些指导吗？

我的 Startup.cs 配置方法有这个 -

        IEdmModel model = this.GetEdmModel(app.ApplicationServices);

        IList<IODataRoutingConvention> routingConventions = new List<IODataRoutingConvention>();
        routingConventions.Insert(0, new MatchAllRoutingConvention());
        app.UseMvc(routeBuilder => routeBuilder.MapODataServiceRoute("odata", "odata", model, new CustomPathHandler(), routingConventions));

CustomPathHandler.cs -

public class CustomPathHandler : DefaultODataPathHandler
{
    public override ODataPath Parse(string serviceRoot, string odataPath, IServiceProvider requestContainer)
    {
        var path =  base.Parse(serviceRoot, odataPath, requestContainer);
        return path;
    }

    public override string Link(ODataPath path)
    {
        return base.Link(path);
    }
}

ODataEndpointController.cs -

public class ODataEndpointController : ODataController
{
    [EnableQuery]
    [ODataRoute]
    public EdmEntityObjectCollection Get()
    {
        // Get entity set's EDM type: A collection type.            
        ODataPath path = Request.ODataFeature().Path;
        IEdmCollectionType collectionType = (IEdmCollectionType)path.EdmType;
        IEdmEntityTypeReference entityType = collectionType.ElementType.AsEntity();

        // Create an untyped collection with the EDM collection type.
        EdmEntityObjectCollection collection =
            new EdmEntityObjectCollection(new EdmCollectionTypeReference(collectionType));

        // Add untyped objects to collection.
        DataSourceProvider.Get(entityType, collection);

        return collection;
    }

MatchAllRoutingConvention.cs

public class MatchAllRoutingConvention : IODataRoutingConvention
{
    public IEnumerable<ControllerActionDescriptor> SelectAction(RouteContext routeContext)
    {
        ControllerActionDescriptor test = new ControllerActionDescriptor();
        test.ControllerName = "ODataEndpoint";
        return new List<ControllerActionDescriptor> { test }.AsEnumerable();

    }

}

我在这里做错了什么吗？当我尝试点击http://localhost:port/odata/Products 时，我得到一些source is null错误

编辑（1 月 15 日）：

如下修改 MatchAllRoutingConvention 会根据需要重定向路由，但任何 $metadata 请求（抛出异常）也是如此。并且 $filter 查询也不起作用。因此，任何指示/提示都会有所帮助-

public class MatchAllRoutingConvention : IODataRoutingConvention
{
    public IEnumerable<ControllerActionDescriptor> SelectAction(RouteContext routeContext)
    {
        ControllerActionDescriptor odataControllerDescriptor = new ControllerActionDescriptor
            {
                ControllerName = "ODataEndpoint",
                ActionName = "Get",
                Parameters = new List<ParameterDescriptor>(),
                FilterDescriptors = new List<FilterDescriptor>(),
                BoundProperties = new List<ParameterDescriptor>(),
                MethodInfo = typeof(ODataEndpointController).GetMethod("Get"),
                ControllerTypeInfo = typeof(ODataEndpointController).GetTypeInfo()
            };

            return new List<ControllerActionDescriptor> { odataControllerDescriptor };

    }

}

Answer 1

由于我还没有看到任何回复，因此将其发布为答案，希望这会对某人有所帮助。我修改了 MatchAllRoutingConvention 类如下 -

public class MatchAllRoutingConvention : IODataRoutingConvention
{
    public IEnumerable<ControllerActionDescriptor> SelectAction(RouteContext routeContext)
    {
        if (routeContext.RouteData.Values["odataPath"] == null || 
            routeContext.RouteData.Values["odataPath"].ToString() == "$metadata")
            return new MetadataRoutingConvention().SelectAction(routeContext);

        IActionDescriptorCollectionProvider actionCollectionProvider =
            routeContext.HttpContext.RequestServices.GetRequiredService<IActionDescriptorCollectionProvider>();

        IEnumerable<ControllerActionDescriptor> actionDescriptors = actionCollectionProvider
            .ActionDescriptors.Items.OfType<ControllerActionDescriptor>()
            .Where(c => c.ControllerName == "ODataEndpoint");

        return actionDescriptors;
    }

}

这可以正确服务元数据请求以及简单的实体请求。然而，这不会响应 $filter、$select 等。据我了解，ODataQueryOptions 类用于应用 OData 过滤等，但它们不适用于非 CLR 类。所以不确定这个问题是否有解决方案。

[编辑] 所以我设法解决了这个过滤问题。有一个库LinqToQueryString可以应用于 IQueryable，显然不是 EdmEntityObjectCollection（这并不容易）。

我首先将数据加载到字典中，他们的网站上有一个示例可以做到这一点。首先在该字典上应用 OData 查询选项字符串，然后将筛选结果加载到我的实体中，然后加载到 EdmEntityObjectCollection 中

    var list = new List<IEdmEntityObject>();
    var dataList = new List<Dictionary<string, object>>();

    // Load data in Dictionary
    foreach (var item in data)
    {
         var dataItem = new Dictionary<string, object>();

         // Load data

         dataList.Add(dataItem);
    }

    var filteredDataList = dataList.AsQueryable().LinqToQuerystring(oDataQuery);

    // Now add filtered/sorted etc data in EdmEntityObject
    foreach (var item in filteredDataList)
    {
         var entity = new EdmEntityObject(entityType);
         foreach (var key in item.Keys)
            entity.TrySetPropertyValue(key, item[key].ToString());
         list.Add(entity);
    }