How to use dynamic expressions in Openbravo
– Amar Singh, Sysfore
Dynamic Expressions are used to obtain values that can depend on session values. For example they can be used to to filter the records that appear in a tab by the ones that were created by the user that has logged into the application.
Depending on how the definitions are; there are different kinds of session values.
It is possible to check (as System Administrator) all current values loaded in session in Openbravo by going to General Setup || Application || Session Variables window.
Session global variables: These values are generated by the java classes and are accessible from anywhere in the Openbravo application.
Columns :Values for all columns used in a tab are accessible as session variables within that tab. Additionally it is also possible to set explicitly a column a session value by setting its Stored in session attribute. This will make this value accessible not only for its tab but also for all the tabs in that window.
Auxillary Inputs are used to create a session value for a concrete tab. This value can be calculated using a Dynamic Expression and its purpose is to use it in other Dynamic expressions within the tab it is defined for.
Auxiliary Inputs are defined in the Openbravo by going to Application Dictionary || Setup || Auxiliary Input tab.
Syntax and types in Dynamic Expressions
Using session values
In Dynamic expressions session values are obtained by their name surrounded by at symbols (@). Thus to get the content of a session value called myValue, it would be done typing @myValue@. Doing it in this manner it would follow the accessibility described above, but it is possible to explicitly obtain the global value (if exists) not taken into account the other ones, to do so the value would have a sharp symbol (#) as prefix. In the previous example it would be @#myValue@.
Dynamic expressions types
There are different types for Dynamic Expression, each type can be used depending on the Application Dictionary object it is defined in. A complete list of all the objects and which kind of expression can use is defined in the next section.
The types are:
Constant :It can be a constant value or a value in stored in session, this type can be used by all the objects. To set this type no prefix is needed.
SQL : Some objects accept SQL expressions. This type must have a @SQL= prefix followed by the SQL clause. It also accepts session values.
WHERE SW_SREQUISITION_ID = @SW_SREQUISITION_ID@
WhereClause : It is a SQL where clause, in this case it is not necessary to add the @SQL= prefix.
Checks : It is used to obtain a boolean value. It does not have any prefix.
· = instead of ==
· ! instead of !=
· & instead of &&
· | instead of ||