How to work with CAP CDS > 7 ? .How do i access and modify req.query in custom handlers?

[michaelschmid03]

When developing CAP CDS for Node.js I regularly had Custom Handlers in which I needed to read some part of the req.query object to make some other backend calls, sometimes I even had to modify the pre-generated queries so that they would properly work on a backend.

Let's take a look on what changed with CDS(here version 7.4.0)

As you can see, req.query.SELECT only contains a from section. Some other params like filter, limit and orderBY are not in this query object, but in Symbol(Original). -Why?

This makes developing with CAP a bit more confusing and more difficult for me.

For Example last week I had accessed a filter with req.req.query.$filter and tried to parse those filter back to CQL, so I could modify and then reattach it to the query parameters. But this doesn't seem like a good Practice

Are there new Best Practices when working with req.query in Custom Handlers using the newer CDS versions? How can I Access req.query.Symbol(Original) in my custom handlers (something like req.query.Symbol(Original) or req.query.['Symbol(Original'] doesnt work)?

Any Guidance or reference to documentation would be massively helpful.

[david_kunz2]

Hi michaelschmid03 ,

You must not access Symbol(original), this is not public API.

Your handler must only take care of req.query, as is.

Note: Some properties might be part of the prototype chain.

Best regards,
David

[michaelschmid03]

okay, then but how can i edit and read the Params of a query like .limit .filter and orderBy of a query, if those aren't inside the req.query object but only in Symbol(original)?

[david_kunz2]

Your handler must not take into account Symbol(original). It must only take into account req.query. If there's some property missing, your handler must not take that property into account.

[michaelschmid03]

Sorry for bothering you again david.kunz2 , I realize that this would work fine in the case of odata services, but in some cases I also have rest services or odata services that aren't obeying all typical odata conventions, So in these cases that wouldn't be an option right? I failed to mention this in my initial question.

[david_kunz2]

Hi Michael, no bother at all 🙂

req.query is normalized across different incoming protocols (OData, REST, GraphQL, ...).

[EkanshCapgemini]

Hi david.kunz2,

I have the exact same question. Could you please explain what you meant by `If there's some property missing, your handler must not take that property into account.` ?

How do I access the parsed filters etc.? Why does CAP assumes that my business logic doesn't need the passed filters?

Br, Ekansh

[david_kunz2]

Hi ekansh005 ,

You have access to the parsed filters in req.query.SELECT.where and req.query.SELECT.from.ref, depending how the service is called.

Best regards,

David