CAP business services : use distinct with projection vs use key with variant as select

[former_member596986]

Hi,

I am trying to write a cds projection using reference as blog-example and documentation. i am not able to write "as projection" statement with distinct keyword. (or alternatively cds variant "as select" with key defined).

The below code works fine, but i am expecting distinct values in result.

using {aatp.risk as riskSchema} from '../db/risk-schema'; 
@path:'dashboard' service DashboardService
{
entity RiskInputData as projection on riskSchema.riskInputData;
entity Plant as projection on RiskInputData { key plant}; 
entity MrpController as projection on RiskInputData { key plant, key mrpController}; 
}

Alternatively, if ii write the same with "as select" statements below, i am getting a OData error >>

using {aatp.risk as riskSchema} from '../db/risk-schema'; 
@path:'dashboard' service DashboardService
{
entity RiskInputData as projection on riskSchema.riskInputData;
entity Plant as select distinct plant from RiskInputData; 
entity MrpController as select distinct a.plant, a.mrpController from RiskInputData as a;
}

[0] srv.json:931: Error: Entity "DashboardService.MrpController" does not 
have a key: ODATA entities must have a key
[0] srv.json:970: Error: Entity "DashboardService.Plant" does not have a key: ODATA entities must have a key

Regards

[former_member628556 · Accepted solution]

With SELECT, you were on the right track, but please also specify the keys there, too.
You might also want to use the CDS-like syntax (FROM first, which is better for code completion)

using {aatp.risk as riskSchema} from '../db/risk-schema'; 
@path:'dashboard' service DashboardService
{
entity RiskInputData as select from riskSchema.riskInputData;
entity Plant as select from RiskInputData distinct { key plant}; 
entity MrpController as select from RiskInputData distinct { key plant, key mrpController}; 
}

(OK, we should probably allow the DISTINCT also directly after the SELECT…, but this is how it works now and will continue to work.)