4.5.3.2.3. Query Filter

A datasource query can be modified during the work of the application, depending on conditions entered by the user. This allows you to efficiently filter data at the level of selection from DB.

The easiest way to provide such ability is to connect a special visual component, Filter, to a datasource.

If by any reason the use of a universal filter is unwanted, a special XML markup can be embedded into a query text. This will allow to create a resulting query based on values entered by the user into any visual components of the screen.

In this filter the following elements can be used:

  • filter – a root element of the filter. It can directly contain only one condition.

    • and, or – logical conditions, may contain any number of other conditions and statements.

    • c – JPQL statement, which is added into the where section. It contains only the text and an optional join attribute, which value will be added into a corresponding place of the query.

Conditions and statements are added into the resulting query only if parameters inside contain values, i.e., they are not null.

Warning

Use only custom, param and component parameters in query filters. ds and session parameters will not work as expected.

Example:

<query>
    select distinct d from app$GeneralDoc d
    <filter>
        <or>
            <and>
                <c join=", app$DocRole dr">dr.doc.id = d.id and d.processState = :custom$state</c>
                <c>d.barCode like :component$barCodeFilterField</c>
            </and>
            <c join=", app$DocRole dr">dr.doc.id = d.id and dr.user.id = :custom$initiator</c>
        </or>
    </filter>
</query>

In this case, if state and initiator parameters are passed into the refresh() method of a datasource, and a visual component, barCodeFilterField, has some value specified, then the resulting query will be as follows:

select distinct d from app$GeneralDoc d, app$DocRole dr
where
(
  (dr.doc.id = d.id and d.processState = :custom$state)
  and
  (d.barCode like :component$barCodeFilterField)
)
or
(dr.doc.id = d.id and dr.user.id = :custom$initiator)

If, for example, the barCodeFilterField component is empty and only one parameter, initiator, was passed into the refresh() method, the query will be as follows:

select distinct d from app$GeneralDoc d, app$DocRole dr
where
(dr.doc.id = d.id and dr.user.id = :custom$initiator)