Problem accessing single entity using OData v4

[ceedee666]

Hi all,

I created a simple project using the CAP and Node.js. The sources are available here: https://github.com/ceedee666/rqk_ws19_v3/. My project just consist of a single CDS entity called SurveyResponses, which is exposed via a service. The CDS of the entity looks like this:

namespace de.fhaachen.rqkws19;
entity SurveyResponses {   key ID : UUID;   orderid : Integer;   orderDate : DateTime;   ...}

After adding some dummy data to the database using an SQL script I' able to access all the entities in the DB using this URL: /survey/SurveyResponses

In OData v4 it is possible to address a single entity via its identifier. Here is an example with the Northwind service on the odata.org: https://services.odata.org/Experimental/OData/OData.svc/Persons(0). When I try the same using my service, e.g. using this URL /survey/SurveyResponses('E65A56807C68EFCA160009027C5C71B7'), I get the following error message:

Expected uri token 'ODataIdentifier' could not be found in 'SurveyResponses('E65A56807C68EFCA160009027C5C71B7')' at position 17

When I try to access an entity using the following $filter expression: /survey/SurveyResponses?$filter=ID eq E65A56807C68EFCA160009027C5C71B7, I get this error message

Property 'E65A56807C68EFCA160009027C5C71B7' does not exist in type 'SurveyService.SurveyResponses'

However, If I try to access the orderid property using a filter everything works as expected. The request to /survey/SurveyResponses?$filter=orderid eq 263 results in

{
  "@odata.context": "$metadata#SurveyResponses",
  "@odata.metadataEtag": "W/\"v7XePRvoicjsrRX1rhd6CPTx23lX+KlEgqRqmcp4pts=\"",
  "value": [
    {
      "ID": "E65A56807C68EFCA160009027C5C71B7",
      "orderid": 263,
      "orderDate": "2019-10-09T14:40:18Z",
      "netPromoterScore": 4,
      "review": "",
      "marketingOptIn": false,
      "responseDate": null,
      "status": 1
    }
  ]
}

Any Idea how to solve this? Did I miss something in the definition of the entity or the service?

Thanks in advance.
Christian

[ceedee666]

I changed the CDS to this

entity SurveyResponses {
    key ID          : UUID @odata.Type:'Edm.String';
    orderid         : Integer;

Now I'm able to access individual entities using the following URL: /survey/SurveyResponses('E65A56807C68EFCA160009027C5C71B7'). The single quotes are now required to be a vaild Edm.String.

The underlying problem seems to be that I create the entries in the DB using the SQL function SYUUID. This function generates UUID in the format shown in the URL above. In contrast, Edm.GUID requires the following format: 'dddddddd-dddd-dddd-dddd-dddddddddddd' where each d represents [A-Fa-f0-9] (cf. https://www.odata.org/documentation/odata-version-2-0/overview/). I'll try again with the correct Edm.GUID format.

Christian

[pierre_dominique2]

Hi,

You don't need to add single quotes. This should work:

/survey/SurveyResponses(E65A56807C68EFCA160009027C5C71B7)

EDIT: by default UUIDs are mapped to Edm.Guid but you can change this behavior if you want -> https://cap.cloud.sap/docs/guides/domain-models#mapping-uuids-to-odata

Cheers,

Pierre

[ceedee666]

Hi pedrodem,

thanks for the response.

Without single quotes I get the following error message: null'E65A56807C68EFCA160009027C5C71B7' is not a valid key. This error originates form the method _parseCompoundKey.

Best
Christian

[ceedee666]

After adding test data in the correct format into the data base (dddddddd-dddd-dddd-dddd-dddddddddddd) the request now works as expected.

With the URL /survey/SurveyResponses(E65A5680-7C68-EFCA-1600-09027C5C71B7) the result is

{
  "@odata.context": "$metadata#SurveyResponses/$entity",
  "@odata.metadataEtag": "W/\"v7XePRvoicjsrRX1rhd6CPTx23lX+KlEgqRqmcp4pts=\"",
  "ID": "E65A5680-7C68-EFCA-1600-09027C5C71B7",
  "orderid": 263,
  "orderDate": "2019-10-09T14:40:18Z",
  "netPromoterScore": 4,
  "review": "",
  "marketingOptIn": false,
  "responseDate": null,
  "status": 1
}

Christian

[vobu]

did you switch back to the alternate keys definition?

entity SurveyResponses {
  key ID: UUID @odata.Type:'Edm.String';
  key orderid : Integer;
//...
}

Would be interesting to see whether the standard approach defined in http://docs.oasis-open.org/odata/odata/v4.01/csprd05/part2-url-conventions/odata-v4.01-csprd05-part2... actually works in your case so that calling both

.../SurveyResponses(ID='some-key-string')
.../SurveyRespones(orderid=4711)
// or even
.../SurveyResponses('some-key-string')
.../SurveyRespones(4711)

would actually work as expected.

PS: can we please have a regular markdown editor in here? grrr.

[ceedee666]

Hi vobu,

no, currently I have the initial version:

entity SurveyResponses {
     key ID: UUID;

This works as expected using a correct Edm.GUID (dddddddd-dddd-dddd-dddd-dddddddddddd). Best part is that when adding an entity using a POST request the correct GUID is created automatically.

Having alternate keys is a great idea as well. I will try this out next and post the results here.
But what is the difference between the two versions you posted? For me they look exactly identical, or am I missing something?

Christian

[ArvinWu]

This method not work now.

The entity defined with UUID, and then the remove the single quote in url:

entity SurveyResponses {
     key ID: UUID;

The url should combined like this:

https://<OData service>/survey/SurveyResponses(ID=056ee329-1c04-4e3a-a5e0-ce816bf8e58c,IsActiveEntity=true)