DataSource for Xamarin.Android: Getting Started
To use RadDataSource developers first need raw data in a collection of some sort. Then RadDataSource can be constructed like this:
// This method gets the raw data from somewhere. (web service, file etc.)
Java.Util.ArrayList rawData = GetData();
RadDataSource dataSource = new RadDataSource(rawData);
Once the data source is constructed the data can be filtered, sorted and grouped:
public class Person : Java.Lang.Object
{
public int age;
public string name;
public string nationality;
}
public class AgeFilterDescriptor : Java.Lang.Object, IFunction
{
public Java.Lang.Object Apply(Java.Lang.Object argument)
{
Person person = (Person)argument;
return person.age < 18;
}
}
public class NameSortDescriptor : Java.Lang.Object, IFunction2
{
public Java.Lang.Object Apply(Java.Lang.Object arg1, Java.Lang.Object arg2)
{
Person person1 = (Person)arg1;
Person person2 = (Person)arg2;
return person1.name.CompareTo(person2.name);
}
}
public class NationalityGroupDescriptor : Java.Lang.Object, IFunction
{
public Java.Lang.Object Apply(Java.Lang.Object argument)
{
Person person = (Person)argument;
return person.nationality;
}
}
The order in which the descriptors are added does not matter. RadDataSource always filters first, sorts second and groups last.
Finally when the data is processed it can be consumed in two ways. One is the View() method, which returns the data in full hierarchy (if grouped multiple times). The other is the FlatView() method which, as the method name says, returns the hierarchical data flattened to a single level. Both methods return lists of DataItem
foreach (Java.Lang.Object data in dataSource.FlatView())
{
DataItem dataItem = data.JavaCast<DataItem>();
if (dataItem.Entity () == null) {
Console.WriteLine (dataItem.GroupKey().ToString());
} else {
Console.WriteLine (dataItem.Entity().ToString());
}
}
RadDataSource never modifies the raw data provided.
To see how to use RadDataSource with RadListView have a look at this article.