Calling a Swagger service from Apex using openapi-generator

For a demo I needed to make calls to the Petstore API using a Swagger / OpenAPI definition from Apex. Unfortunately the Apex support that External Services in Salesforce provides is only callable from Flows so I needed another approach. Using openapi-generator and installing via Homebrew it went relatively smoothly anyway.

It’s always nice to stand on the shoulder of giants so the examples provided by Rene Winkelmeyer (Connecting to Swagger-backed APIs with Clicks or Code ) came in handy. Unfortunately didn’t work as the prefix for the generated classes was different plus the petId was was 1 and not 100. Anyway again easy to fix.

Below are my steps to get working using Homebrew and Salesforce DX.

$ brew install openapi-generator
$ openapi-generator generate \
-i https://raw.githubusercontent.com/openapitools/openapi-generator/master/modules/openapi-generator/src/test/resources/2_0/petstore.yaml \
-g apex \
-o /tmp/petstore_swagger/
$ cd /tmp/petstore_swagger
$ sfdx force:org:create \
-v my_devhub \
-f config/project-scratch-def.json -a petstore_swagger
$ sfdx force:source:push -u petstore_swagger
$ sfdx force:apex:execute -u petstore_swagger
>> Start typing Apex code. Press the Enter key after each line,
>> then press CTRL+D when finished.
OASClient client = new OASClient();
OASPetApi api = new OASPetApi(client);
Map<String,Object> params = new Map<String, Object>();
Long petId = Long.valueOf('1');
params.put('petId', petId);
OASPet pet = api.getPetById(params);
System.debug(pet);
<Ctrl-D>