Adding Functionality to the Web Service

This article has been excerpted from book "A Programmer's Guide to ADO.NET in C#".

Now, why don't you ask the web service to do some more work than just returning data from a database table?

This time I'm going to write to the database. I read data from a client in the form of an array, place it in a dataset, and then add the data to the orders table of the Northwind database.

To do so, I open the OrderRetrievalService project and generate a dataset by using right-click > Generate DataSet option of the data adapter. The Generate DataSet option of the date adapter generates a typed dataset and adds the class DataSet1, which from the dataset.

Now I add a new web method called InsertOrder (see Listing 8-5). In this method, I read data from a database using a data adapter and filled data from the data adapter to a dataset using the data adapter's Fill method. As you can see from Listing 8-5, I've used a SELECT * query with ORDER BY for the OrderId column values.

It gets the last OrderId in the table to determine what is the next available OrderId value. Then it creates a new DataRow in the dataset and populates the row with data passed in from the client. Finally, it calls the Update method of the data adapter to save the new row into the database.

Listing 8-5 Web service method for populating an order in the database

        [WebMethod(Description = "Insert Order from Array")]

        public int InsertOrder(string[] OrderInfo)

        {

            DataSet1 ds = new DataSet1();

            oleDbDataAdapter1.SelectCommand.CommandText = "select * from orders ORDER BY OrderId";

            oleDbDataAdapter1.Fill(ds, "Orders");

            DataRow drLast = ds.orders.Rows[ds.orders.Rows.Count - 1];

            int LastOrderId = Convert.ToInt32(drLast["OrderId"]);

            DataSet1.ordersRow dr = ds.orders.NewordersRow();

            dr.OrderID = LastOrderId + 1;

            dr.OrderDate = Convert.ToDateTime(OrderInfo[0]);

            dr.ShipName = OredrInfo[1];

            dr.ShipAddress = OredrInfo[2];

            dr.ShipCity = OredrInfo[3];

            dr.ShipCountry = OredrInfo[4];

            dr.ShipPostalCode = OredrInfo[5];

            ds.orders.AddordersRow(dr);

            oleDbDataAdapter1.Update(ds, "Orders");

            return dr.OrderID;

        }

Now build and test the service. This service now has two methods, as shown in Figure 8-21.

Figure 8-21. The InsertOrder and GetOrderFromDatabase methods of OrderRetrievalService

Now it's time to test your newly added Web method InsertOrder. To test this service, follow the same steps as in the previous section when testing your GetOrderFromDataSet method.

Create a web application project using VS.NET. You can even use the same client you used to test the GetOrderFromDatabase method. Create a new project called AddOrderClientApp (see Figure 8-22).

Figure 8-22. Creating a client to test the InsertOrder web method

The next step is to add a Web reference to the Web service by right-clicking on the References node of a project in the Solution Explorer and clicking on the Add Web reference option.

Note: If you're using same client application you used last time, you need to remove the namespace and then add it again by using the add Web Reference option to get the latest updated Web service contents.

Again, follow the same steps as in the last sample. Type the URL of your service in the Address text box and click the Add Reference button, which adds the mcb namespace (or localhost if you're using default localhost as the web server) to the project. Add Reference also generates the *.disco, *.wsdl, and proxy files. Now you can call your Web service. Add some controls to the page to make it look like Figure 8-23. I added six text boxes to accept the order date, name, address, city, country, and zip of a customer. The enter order button submits the order to the service.

Figure 8-23. Design view of the order customer entry web service

Again, double-click on the Enter Order button use the code in listing 8-6 to populate the order array and pass it to the Web service. The enter order button event handler looks like listing 8-6.

Listing 8-6. Client event handler for executing the Web service

        private void Button1_Click(object sender, System.EventArgs e)

        {

            string[] orderData = new string[5];

            orderData[0] = TextBox1.Text;

            orderData[1] = TextBox2.Text;

            orderData[2] = TextBox3.Text;

            orderData[3] = TextBox4.Text;

            orderData[4] = TextBox5.Text;

            mcb.Service1 myWebService = new mcb.Service1();

            myWebService.InsertOrder(orderData);

        }

The button event handler assigns a strings array with information typed into the order form. You can create an instance of the service by directly using mcb.Service1 and calling the InsertOrder method. If you're using localhost as your Web server, the code would look like the following:

        localhost.Service1 myWebService = new localhost.Service1();

        myWebService.InsertOrder(orderData);

As you can see from figure 8-24, the InsertOrder method is available in the list. 

Figure 8-24. The InsertOrder method available in the list

Now build and run the application. The output looks like figure 8-25. Now you enter customer data and clicking the enter order button adds the data to the orders table.

Figure 8-25. Adding an order to the database using Enter order

Conclusion

Hope this article would have helped you in understanding adding Functionality to the Web Service. See other articles on the website also for further reference.

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