public void TestFirstOrDefault()
{
// create QueryDesigner with ElementType == Products
var queryDesinger = new QueryDesigner(context, typeof(Products));
//create root node which elementType has the same type in queryDesigner
var root = new JoinNode(typeof(Products));
// create child node Categories with propertyName "Products".
// Because Categories linked with Products by next property:
// public EntitySet<Products> Products
var categoryNode = new JoinNode(typeof(Categories), "Category", "Products");
// add categoryNode to root node
root.AddChildren(categoryNode);
// create filter by Products.ProductName like "%l%"
var productNameCondition = new Condition("ProductName", "l", ConditionOperator.Like);
root.AddConditions(productNameCondition);
// create filter by Categories.Description like "Sweet%"
var categoryNameCondition = new Condition("Description", "Sweet", ConditionOperator.StartsWith, typeof(Categories));
categoryNode.AddConditions(categoryNameCondition);
// make join Products table with Categories filtered by conditions
// and ordered by already created ordering
queryDesinger.Join(root);
object first = queryDesinger.FirstOrDefault();
Assert.IsInstanceOfType(typeof(Products), first);
}
