Does Olingo support the usage of user-defined functions in $filter query?

[Zhiqiang Ren <al...@gmail.com>]

Hi all,

I am newbie to OData and Olingo. Currently I want to build a query service
following the syntax of the $filter query in OData. I am using the Olingo
library for parsing the $filter query string.

It seems that OData V4 supports the usage of user-defined function in
$filter query. (Correct me if I am wrong.) The following query
"$filter=xx.Myfun(x=xx.Myfun(x=3)) eq 1" can be parsed by the Olingo
library for OData V4 if CsdlAbstractEdmProvider is implemented
appropriately. However, I notice that the result is of type "expression",
which has no subclass for the structure of function call. Is it true that
Olingo does not support the usage of user-defined functions in $filter
query? Thanks.

RE: Does Olingo support the usage of user-defined functions in $filter query?

["Grande, Oliver" <ol...@sap.com>]

Hello Zhiqiang,

actually Olingo is able to do so.

I tried it out. In my example implementation I have an entity storing the population and the area of a region. The area is stored in m2 . I have created a function that calculates the population density. As a density is usually given in  km-2. I convert the area from m2 into km2 before I put it into the density function, which leads to the following URL:

…/AdministrativeDivisions?$filter=test.PopulationDensity(Area=test.ConvertToQkm(Area=$it/Area),Population=$it/Population) gt 1000


What you get with the “expression” is parsed version of $filter expression, which is provided as kind of syntax tree. In my example the “expression” contains as Left the function PopulationDensity, which has a as parameter the other function and so on:

[cid:image003.jpg@01D26CCC.B6E93270]

 I hope that helps.

Regards,
Oliver


Oliver Grande

PI IC HC Clinical Decision Support DE

SAP SE Dietmar-Hopp-Allee 16, 69190 Walldorf, Germany

E oliver.grande@sap.com


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From: Zhiqiang Ren [mailto:alex.ren2006@gmail.com]
Sent: Mittwoch, 11. Januar 2017 22:52
To: user@olingo.apache.org
Subject: Does Olingo support the usage of user-defined functions in $filter query?

Hi all,

I am newbie to OData and Olingo. Currently I want to build a query service following the syntax of the $filter query in OData. I am using the Olingo library for parsing the $filter query string.

It seems that OData V4 supports the usage of user-defined function in $filter query. (Correct me if I am wrong.) The following query "$filter=xx.Myfun(x=xx.Myfun(x=3)) eq 1" can be parsed by the Olingo library for OData V4 if CsdlAbstractEdmProvider is implemented appropriately. However, I notice that the result is of type "expression", which has no subclass for the structure of function call. Is it true that Olingo does not support the usage of user-defined functions in $filter query? Thanks.