We aren’t using it in the present blog, because the ExpressionVisitor is explained in the $filter blog Implementation In order to support such complex sorting, the OData service implementation has to make use of the ExpressionVisitor concept. Additionally, within each country, they should be sorted by their name in ascending order. In this example, all companies should be displayed, and they should be sorted by their country in descending order. Companies?$orderby=COUNTRY desc, NAME asc In that case, the value is specified as comma-separated list. If not specified, the default is ascending.Īs of the OData specification, the $orderby system query option can be applied to multiple properties. The order can be ascending or descending: OData supports this requirement with the system query option $orderby This can depend on the backend data source – anyways, it is undefined.īut the user of an OData service might want to be able to specify the order, according to his needs.įor example, a usual case would be that the list of entities is sorted as per default by its ID number, but for a user, the ID is not relevant and he would prefer a sorting e.g. When requesting a list of entities from a service, it is up to the service implementation to decide in which order they are presented. So let us skip all introductory text and go directly to the implementation. In my previous Blog, I’ve already described how to implement the system query option $top.Įverything described there, motivation, prerequisites, preparation etc, is valid here as well. It shows how to implement the $orderby capability in an OData service based on Integration Gateway. CodeBank - ASP / ASP.This blog is about Integration Gateway (IGW) in SAP Mobile Platform 3.0 (SMP).Slow Chat with the Microsoft Visual Basic team.Universal Windows Platform and Modern Windows Experience.Your Remove method should look like this: Remove, on the other hand, is supposed to take an item as a parameter, not an index, thus it IS dependent on the type of the items. CollectionBase already implements RemoveAt because it takes an Integer parameter and doesn't return anything, thus the type of the items is irrelevant. Note also that you have implemented the Remove method incorrectly. YOU are the inheritor so it's up to YOU to implement them. Members like Item, Add and Remove are all dependent on the type of the objects the collection contains so they are left to the inheritor to implement. For example, the Clear and RemoveAt methods ARE implemented by CollectionBase because they don't care what type of objects the collection contains. As such any members of ArrayList that use type Object are NOT implemented by CollectionBase, but any that don't are. It is supposed to be inherited and extended to provide the same functionality as ArrayList class but strongly-typed. Here's the idea behind the CollectionBase class. Nothing is being shadowed or overloaded because there's nothing to shadow or overload. Did you read the documentation to see what members the CollectionBase class has? It has no Item property, Add method or Remove method.
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