Client Object Model – Part 8

Let us continue exploring client object model. From this post we will explore Silverlight client object model and explore different examples. I would recommend reading part 1 to part 7 first to get to know about client object model and then continue reading from here.

1) Iterating through list items

namespace SilverlightSPCOM
{
public partial class MainPage : UserControl
{
private ClientContext context = null;
private Web web = null;
ListItemCollection listItems;
private delegate void UpdateUIMethod();


public MainPage()
{
InitializeComponent();
}

private void btnRetrive_Click(object sender, RoutedEventArgs e)
{
LoadData();
}

private void LoadData()
{

context = ClientContext.Current;

web = context.Web;

List lstEmployees = web.Lists.GetByTitle("Employees");

CamlQuery Query = new CamlQuery();
Query.ViewXml = "<View/>";

listItems = lstEmployees.GetItems(Query);

context.Load(lstEmployees);
context.Load(listItems);

context.ExecuteQueryAsync(LoadSucces, LoadFailed);

}

private void DisplayData()
{
foreach (ListItem listItem in listItems)
{
lblOutputLabel.Text += Environment.NewLine + "\n" +
"ID: " + listItem.Id + " Title:" + listItem["Title"] + " First Name : " + listItem["First_x0020_Name"]
+ " Last Name" + listItem["Last_x0020_Name"];
}
}

private void LoadSucces(object sender, ClientRequestSucceededEventArgs e)
{
UpdateUIMethod updateUI = DisplayData;
this.Dispatcher.BeginInvoke(updateUI);
}

private void LoadFailed(object sender, ClientRequestFailedEventArgs e)
{
MessageBox.Show("Request Failed: " + e.Message + ", Stack Trace:" + e.StackTrace);
}


}
}

2) Getting only specific properties

Instead of getting all properties of any specific object, if we want to get only specific properties that we are interested in, we can use lambda expression in query. This will result in less network traffic.

namespace SilverlightSPCOM
{
public partial class MainPage : UserControl
{
private ClientContext context = null;
private Web web = null;
ListItemCollection listItems;
private delegate void UpdateUIMethod();


public MainPage()
{
InitializeComponent();
}

private void btnRetrive_Click(object sender, RoutedEventArgs e)
{
LoadData();
}

private void LoadData()
{

context = ClientContext.Current;

web = context.Web;

context.Load(web,
s => s.Title,
s => s.Description);


context.ExecuteQueryAsync(LoadSucces, LoadFailed);

}

private void DisplayData()
{

lblOutputLabel.Text += "Web Title : " + web.Title + Environment.NewLine + "\n" + " Description:" + web.Description ;


}

private void LoadSucces(object sender, ClientRequestSucceededEventArgs e)
{
UpdateUIMethod updateUI = DisplayData;
this.Dispatcher.BeginInvoke(updateUI);
}

private void LoadFailed(object sender, ClientRequestFailedEventArgs e)
{
MessageBox.Show("Request Failed: " + e.Message + ", Stack Trace:" + e.StackTrace);
}


}
}

3) Create a list and list items

namespace SilverlightSPCOM
{
public partial class MainPage : UserControl
{
private ClientContext context = null;
private Web web = null;
private delegate void UpdateUIMethod();


public MainPage()
{
InitializeComponent();
}

private void btnRetrive_Click(object sender, RoutedEventArgs e)
{
LoadData();
}

private void LoadData()
{

context = ClientContext.Current;

web = context.Web;

ListCreationInformation lstCreationListFromSL =
new ListCreationInformation();
lstCreationListFromSL.Title = "List created from silverlight";
lstCreationListFromSL.TemplateType = (int)ListTemplateType.GenericList;
List lstFromSL = web.Lists.Add(lstCreationListFromSL);

Field fldFirstName = lstFromSL.Fields.AddFieldAsXml(@"<Field Type='Text' DisplayName='First Name'/>", true, AddFieldOptions.DefaultValue);
Field fldLastName = lstFromSL.Fields.AddFieldAsXml(@"<Field Type='Text' DisplayName='Last Name'/>", true, AddFieldOptions.DefaultValue);
Field fldAge = lstFromSL.Fields.AddFieldAsXml(@"<Field Type='Number' DisplayName='Age'/>", true, AddFieldOptions.DefaultValue);


ListItemCreationInformation itemCreateInfo = new ListItemCreationInformation();

ListItem listItem = lstFromSL.AddItem(itemCreateInfo);
listItem["Title"] = "1 Item created From SL";
listItem["First_x0020_Name"] = "John";
listItem["Last_x0020_Name"] = "Desilva";
listItem["Age"] = "25";
listItem.Update();

listItem = lstFromSL.AddItem(itemCreateInfo);
listItem["Title"] = "2 Item created From SL";
listItem["First_x0020_Name"] = "Michelle";
listItem["Last_x0020_Name"] = "Alberto";
listItem["Age"] = "24";
listItem.Update();


context.ExecuteQueryAsync(LoadSucces, LoadFailed);

}

private void DisplayData()
{

lblOutputLabel.Text += "List Created successfully and items are also created successfully";


}

private void LoadSucces(object sender, ClientRequestSucceededEventArgs e)
{
UpdateUIMethod updateUI = DisplayData;
this.Dispatcher.BeginInvoke(updateUI);
}

private void LoadFailed(object sender, ClientRequestFailedEventArgs e)
{
MessageBox.Show("Request Failed: " + e.Message + ", Stack Trace:" + e.StackTrace);
}


}
}

Many more examples to come. Keep reading Part-9 of this series.