为XDocument指定默认名称空间会给出空值(Specifiying a default namespace for XDocument gives empty value)

 我认为你在正确的轨道上。 这是我过去所做的： 
 
public class CassandraDAO
{
    private Cluster cluster;
    private Session session;
    private String NODE = ABCServiceTester.Properties.Settings.Default.CASSANDRA_NODE;
    private String USER = ABCServiceTester.Properties.Settings.Default.USERNAME;
    private String PASS = ABCServiceTester.Properties.Settings.Default.PASSWORD;

    public CassandraDAO()
    {
        connect();
    }

    private void connect()
    {
        cluster = Cluster.Builder().WithCredentials(USER, PASS)
            .AddContactPoint(NODE).Build();
        session = cluster.Connect();
    }

    protected Session getSession()
    {
        if (session == null)
        {
            connect();
        }

        return session;
    }
}
 
 通过将我的连接细节隔离在我的CassandraDAO类中，然后为每个键空间或功能区域编写单独的DAO。 这些DAO继承了CassandraDAO类。 
 
public class ProductsDAO : CassandraDAO
{
    public List<Product> getProducts(string _itemID)
    {
        string strCQL = "SELECT priceAvail, productGroup, productSpec, sizeProfile "
            + "FROM products.itemsmaster "
            + "WHERE itemID=?";
        Session localSession = getSession();
        PreparedStatement statement = localSession.Prepare(strCQL);
        BoundStatement boundStatement = new BoundStatement(statement);
        boundStatement.Bind(_itemID);

        //get result set from Cassandra
        RowSet results = localSession.Execute(boundStatement);

        List<Product> returnVal = new List<Product>();

        foreach (Row row in results.GetRows())
        {
            Product tempProd = new Product();
            tempProd.itemID= _itemID;
            tempProd.priceAvail = row.GetValue<int>("priceavail");
            tempProd.productGroup = row.GetValue<string>("productgroup");
            tempProd.productSpec = row.GetValue<string>("productspec");
            tempProd.sizeProfile = row.GetValue<string>("sizeprofile");

            returnVal.Add(tempProd);
        }

        return returnVal;
    }
 
 C＃中没有很多官方的DataStax代码。 我根据我在DataStax Academy上学习Cassandra Java Development类所学到的内容进行了调整。 显然，在这个例子中我没有做MVC，但我希望它有帮助。 

I think you're on the right track. Here is what I've done in the past:
 
public class CassandraDAO
{
    private Cluster cluster;
    private Session session;
    private String NODE = ABCServiceTester.Properties.Settings.Default.CASSANDRA_NODE;
    private String USER = ABCServiceTester.Properties.Settings.Default.USERNAME;
    private String PASS = ABCServiceTester.Properties.Settings.Default.PASSWORD;

    public CassandraDAO()
    {
        connect();
    }

    private void connect()
    {
        cluster = Cluster.Builder().WithCredentials(USER, PASS)
            .AddContactPoint(NODE).Build();
        session = cluster.Connect();
    }

    protected Session getSession()
    {
        if (session == null)
        {
            connect();
        }

        return session;
    }
}
 
With my connection details isolated in my CassandraDAO class, I then write individual DAOs for each keyspace or area of functionality. These DAOs then inherit the CassandraDAO class.
 
public class ProductsDAO : CassandraDAO
{
    public List<Product> getProducts(string _itemID)
    {
        string strCQL = "SELECT priceAvail, productGroup, productSpec, sizeProfile "
            + "FROM products.itemsmaster "
            + "WHERE itemID=?";
        Session localSession = getSession();
        PreparedStatement statement = localSession.Prepare(strCQL);
        BoundStatement boundStatement = new BoundStatement(statement);
        boundStatement.Bind(_itemID);

        //get result set from Cassandra
        RowSet results = localSession.Execute(boundStatement);

        List<Product> returnVal = new List<Product>();

        foreach (Row row in results.GetRows())
        {
            Product tempProd = new Product();
            tempProd.itemID= _itemID;
            tempProd.priceAvail = row.GetValue<int>("priceavail");
            tempProd.productGroup = row.GetValue<string>("productgroup");
            tempProd.productSpec = row.GetValue<string>("productspec");
            tempProd.sizeProfile = row.GetValue<string>("sizeprofile");

            returnVal.Add(tempProd);
        }

        return returnVal;
    }
 
There isn't a whole lot of official DataStax code out there for C#. I adapted this from what I learned by taking the Cassandra Java Development class on DataStax Academy. Obviously, I wasn't doing MVC in this example, but I hope it helps.