Great thing, looks very useful.
> On 11.03.2017, at 23:41, Ricardo Parada <rpar...@mac.com> wrote:
>
> Hi all,
>
> Over the years, I’ve worked on an class for doing ad hoc queries. This class
> has gotten better and better. At first, the API of this class and some
> implementation details were not ready for public consumption in my opinion.
>
> However, recently I took the time to polish the code as much as possible and
> if I can get my employer's approval I would like to contribute this code to
> project Wonder which has given us so much in return during the years.
>
> Here is a preview of its functionality. Please let me know if you guys think
> this would be a useful contribution.
> ERXQuery.java
> This class has a fluent API that mimics a select statement:
> NSArray<NSDictionary<String,Object>> records =
> ERXQuery.create()
> .select (keys)
> .from (entity)
> .where (qualifier)
> .groupBy (groupings)
> .having (havingQualifier)
> .orderBy (sortings)
> .fetch();
>
> Overview
> ERXQuery allows you to use EOF constructs (EOQualifiers, EOAttributes,
> EOSortOrdering, EOAttribute names, relationships, etc.) to create queries of
> the form:
> SELECT ...
> FROM ...
> WHERE ...
> GROUP BY ...
> HAVING ...
> ORDER BY ...
>
> Using Ad Hoc Attributes
> You may use the ERXAdHocAttributes class to easily create ad hoc attributes
> to use with your query. For example, the code below creates two ad hoc
> EOAttributes. An ad hoc attribute is an EOAttribute that is not physically
> attached to an entity and that has a definition. They are useful for
> aggregating other attributes. The definition of the attribute can reference
> relationships and attributes as shown below.
> // Using a single query against the order entity, count the number of
> // orders and line items that match the qualifier.
> ERXAdHocAttributes attributes = ERXAdHocAttributes.create(orderEntity)
> .add("itemCount", "COUNT(DISTINCT lineItems.lineItemID)", "intNumber")
> .add("orderCount", "COUNT(DISTINCT orderID)", "intNumber");
>
> NSDictionary<String,Object> row =
> ERXQuery.create()
> .select (attributes)
> .from (orderEntity)
> .where (qualifier)
> .fetch()
> .lastObject();
>
> int orderCount = ((Number) row.objectForKey("orderCount")).intValue();
> int itemCount = ((Number) row.objectForKey("itemCount")).intValue();
>
> Fetching into a Custom Record Class
> You can also fetch using a custom class of your choice, i.e. Foo, as shown
> below:
> // Using java >= 8 is easy with a lambda expression
> NSArray<Foo> objs = query.fetch(editingContext, (ec, row) -> new Foo(ec,
> row));
>
>
> // Using java < 8 you must provide a RecordConstructor
> ERXQuery.RecordConstructor<Foo> recordConstructor =
> new ERXQuery.RecordConstructor<Foo> {
> @Override
> public Foo constructRecord(EOEditingContext ec, NSMutableDictionary
> row) {
> return new Foo(ec, row);
> }
> };
>
> NSArray objs = query.fetch(editingContext, recordConstructor);
>
> Author: Ricardo J. Parada
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Markus Ruggiero
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Check out the new book about Project Wonder and WebObjects on
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