如何从WCF服务将表数据发送到客户端

Question

public DataTable Get_table_data()
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("Id");
        dt.Columns.Add("user_name");
        dt.Columns.Add("user_email");
        dt.Columns.Add("status");
        dt.Columns.Add("Role");
        DataRow data_table_new_row = null;
        var rows = (from s in db.logins
                  where s.status == 1
                  select s);

        foreach (var r in rows)
        {
            data_table_new_row= dt.NewRow();
            dt.Rows.Add(r.Id,r.user_name,r.user_email,r.status,r.Role);
        }
        int c = dt.Rows.Count;
        return dt;
    }

i trying to make WCF application. i want to get all table data from table and return data to client application.i have converted linq data to tabledata. but it gives me error that wcf does not support for this type of return type.

Answer 1

You can return a DataSet to your client, in which case you will just need to update your method return type, add the DataTable to the DataSet, and return it to the client.

However, DataSets are not the best option for data transfer in WCF. Instead, try creating your own custom data transfer objects (DTO), hydrate them from your LINQ query, and return the DTOs to your caller.

You can find out more about WCF DataContracts here:

http://msdn.microsoft.com/en-us/library/ms733127%28v=vs.110%29.aspx

Here is a hypothetical User DTO:

[DataContract]
public class User
{
   [DataMember]
   public int Id {get;set;}
   [DataMember]
   public string UserName {get;set;}
   [DataMember]
   public string Password {get;set;}
}

I also suggest using the Request/Response pattern with WCF, in which case you will also need a Response DTO with a list of your User DTOs:

[DataContract]
public class Response
{
   [DataMember]
   public bool Success {get;set;}
   [DataMember]   
   public string Message {get;set;}
   [DataMember]
   public List<User> Users {get;set;}
}

Answer 2

It is generally not recommended to return a DataTable in WCF. It is very large and bulky to send over the wire. It is not the best design either.

Instead create your own class and send a List of those objects to the client.

Define your class using DataContractAttribute and DataMemberAttribute :

[DataContract]
public class User
{
    [DataMember]
    public int Id { get; set; }
    [DataMember]
    public string UserName { get; set; }
    [DataMember]
    public string UserEmail { get; set; }
    [DataMember]
    public int Status { get; set; }
    [DataMember]
    public string Role { get; set; }
}

Then in your foreach loop just populate the List<User> collection and return that instead.

var listOfUser = new List<User>();
foreach (var r in rows)
{
    var user = new User();
    user.Id = r.Id;
    user.UserName = r.user_name;
    user.UserEmail = r.user_email;
    user.Status = r.status; 
    user.Role = r.Role;
    listOfUser.Add(user);
}
return listOfUser;