A 'return' expression required in a function with a block body ('{...}'

Question

I want to call api using rxjava3 inside getCampaigns function in CampaignRepositoryImpl.kt class but I am getting following error A 'return' expression required in a function with a block body ('{...}')

below CampaignRepositoryImpl.kt class

import de.westwing.campaignbrowser.domain.Campaign
import de.westwing.campaignbrowser.domain.CampaignRepository
import io.reactivex.rxjava3.core.Single

class CampaignRepositoryImpl(private val apiInterface: ApiInterface) : CampaignRepository {

    override fun getCampaigns(): Single<List<Campaign>> {

       apiInterface.getCampaigns()

    }

}

below my interface class I am getting API call

interface ApiInterface {

    @GET("cms/test/campaigns.json")
    fun getCampaigns(): Single<CampaignsResponse>

}

below CampaignRepository

interface CampaignRepository {

fun getCampaigns(): Single<List<Campaign>>

}

below my CompaignResponse.kt

data class CampaignsResponse(val metadata: CampaignsMetadata)

below CampaingsMetadata

data class CampaignsMetadata(val data: List<CampaignDto>)

below

data class Campaign(val name: String, val description: String)

below CampaignDto

class CampaignDto(val name: String, val description: String, val image: ImageDto)

I want to know where I am making mistake what I have to do in order to avoid error

Answer 1

From your api interface, we can see that the type of getCampaigns() is Single<CampaignsResponse>. In your repository implementation, on the other hand, the type of getCampaigns() is Single<List<Campaign>>.

Since both are Single<Foo>, you'll need to map from one to the other.

Given your class implementations, this should work:

override fun getCampaigns(): Single<List<Campaign>> {
   return apiInterface.getCampaigns().map { response ->
       response.metadata.data.map {
           Campaign(it.name, it.description)
       }
   }
}

This map call is taking a CampaignResponse and turning it into a List<Campaign>.