/// <summary>
/// Creates a new expression that is like this one, but using the supplied children. If all of the children are the same, it will
/// return this expression.
/// </summary>
/// <param name="projectionBindingExpression"> The <see cref="ProjectionBindingExpression" /> property of the result. </param>
/// <returns> This expression if no children changed, or an expression with the updated children. </returns>
public virtual CollectionResultExpression Update(ProjectionBindingExpression projectionBindingExpression)
{
Check.NotNull(projectionBindingExpression, nameof(projectionBindingExpression));
return(projectionBindingExpression != ProjectionBindingExpression
? new CollectionResultExpression(projectionBindingExpression, Navigation, ElementType)
: this);
}
private object GetProjectionIndex(ProjectionBindingExpression projectionBindingExpression)
{
return(projectionBindingExpression.ProjectionMember != null
? ((ConstantExpression)_selectExpression.GetMappedProjection(projectionBindingExpression.ProjectionMember)).Value
: (projectionBindingExpression.Index != null
? (object)projectionBindingExpression.Index
: projectionBindingExpression.IndexMap));
}
/// <summary>
/// Creates a new instance of the <see cref="CollectionResultExpression" /> class.
/// </summary>
/// <param name="projectionBindingExpression"> An expression reprensenting how to get the subquery from SelectExpression to get the elements. </param>
/// <param name="navigation"> A navigation associated with this collection, if any. </param>
/// <param name="elementType"> The clr type of individual elements in the collection. </param>
public CollectionResultExpression(
ProjectionBindingExpression projectionBindingExpression,
INavigationBase?navigation,
Type elementType)
{
ProjectionBindingExpression = projectionBindingExpression;
Navigation = navigation;
ElementType = elementType;
}
private ShapedQueryExpression AggregateResultShaper(
ShapedQueryExpression source, Expression projection, bool throwOnNullResult, Type resultType)
{
var selectExpression = (SelectExpression)source.QueryExpression;
selectExpression.ReplaceProjectionMapping(
new Dictionary <ProjectionMember, Expression>
{
{ new ProjectionMember(), projection }
});
selectExpression.ClearOrdering();
Expression shaper = new ProjectionBindingExpression(source.QueryExpression, new ProjectionMember(), projection.Type);
if (throwOnNullResult)
{
var resultVariable = Expression.Variable(projection.Type, "result");
shaper = Expression.Block(
new[] { resultVariable },
Expression.Assign(resultVariable, shaper),
Expression.Condition(
Expression.Equal(resultVariable, Expression.Default(projection.Type)),
Expression.Throw(
Expression.New(
typeof(InvalidOperationException).GetConstructors()
.Single(ci => ci.GetParameters().Length == 1),
Expression.Constant(CoreStrings.NoElements)),
resultType),
resultType != resultVariable.Type
? Expression.Convert(resultVariable, resultType)
: (Expression)resultVariable));
}
else if (resultType.IsNullableType())
{
shaper = Expression.Convert(shaper, resultType);
}
source.ShaperExpression = shaper;
return(source);
}
/// <summary>
/// Creates a new expression that is like this one, but using the supplied children. If all of the children are the same, it will
/// return this expression.
/// </summary>
/// <param name="projectionBindingExpression">The <see cref="ProjectionBindingExpression" /> property of the result.</param>
/// <returns>This expression if no children changed, or an expression with the updated children.</returns>
public virtual CollectionResultExpression Update(ProjectionBindingExpression projectionBindingExpression)
=> projectionBindingExpression != ProjectionBindingExpression
? new CollectionResultExpression(projectionBindingExpression, Navigation, ElementType)
: this;