问题描述:

I'm Hosting an OData Service which exposes certain tables and properties from my DB.

I can Request the Metadata for the DB using the [hosturl]?$metadata property.

which return the table names and columns in XML format.

I was wondering if there is a built in OData class to parse this, so that I can grab out the Tables, and Columns or do I have to do It manually?

网友答案:

You can use ODataLib to parse the metadata model as described here:

http://odata.jenspinney.com/2013/02/creating-an-iedmmodel-from-a-metadata-document/

网友答案:

So I figured out a way to do it, you will also need the class from @Vagif's post which you can find here:

http://odata.jenspinney.com/2013/02/creating-an-iedmmodel-from-a-metadata-document/

This is a simple funciton to grab out the properties, It could be optimized to cache the tables names etc but this is more for testing purposes.

    private static IEdmModel GetODataEdmModel()
    {
        IEdmModel edmModel = null;
        string FullUrl = "http://localhost:4684/BDBWcfService.svc/$metadata/";


        var request = WebRequest.CreateHttp(FullUrl);
        var metadataMessage =
            new ClientHttpResponseMessage((HttpWebResponse)request.GetResponse());
        using (var messageReader = new ODataMessageReader(metadataMessage))
        {
            edmModel = messageReader.ReadMetadataDocument();
        }
        return edmModel;
    }

    public ActionResult ODataGetProperties(string TableName)
    {
        DataModel = (DataModel == null) ? GetODataEdmModel() : DataModel;

        //gets a mapping of the tables names
        var TableNames = DataModel.SchemaElements.OfType<IEdmEntityContainer>().Single().Elements.OfType<IEdmEntitySet>().ToDictionary(k => k.Name, v => v.ElementType.Name);

        string TypeName = string.Empty;
        if (TableNames.TryGetValue(TableName, out TypeName))
        {
            //uses the type name to look up the properties
            var data = DataModel.SchemaElements.OfType<IEdmEntityType>().Where(k => k.Name == TypeName).Select(v => new
            {
                NavigationProperties = v.NavigationProperties().Select(p => p.Name).ToList(),
                Properties = v.Properties().Select(p => p.Name).ToList(),
            }).FirstOrDefault();

            var JSSerializer = new JavaScriptSerializer();
            var json = JSSerializer.Serialize(data);
            return Json(data, JsonRequestBehavior.AllowGet);

        }
        return new HttpStatusCodeResult(HttpStatusCode.NotFound, "The Requested Table was not found please refine your query");
    }
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