How to specify a different name for json key while using Retrofit + Moshi

Question

I need to make a POST request to my backend with following json:

{
    start_time: 123456789
}

I have created the below data class for the body in Retrofit request:

data class MyRequestBody(
    @Json(name="start_time")
    val startTime: Long
)

But when I check on my backend the request contains the startTime field instead of start_time. How can I change the name of this variable for json serialization?

Edit: My build.gradle:

implementation "com.squareup.retrofit2:retrofit:2.9.0"
implementation "com.squareup.retrofit2:converter-moshi:2.9.0"

My api interface:

internal interface RemoteTopicApi {

    @POST("xyz/")
    suspend fun getData(@Body body: MyRequestBody)

}

Retrofit Builder:

Retrofit.Builder()
    .baseUrl(BASE_URL)
    .addConverterFactory(MoshiConverterFactory.create())
    .build()

https://stackoverflow.com/questions/21398598/how-to-post-raw-whole-json-in-the-body-of-a-retrofit-request — Marcin Orlowski, Aug 28 '22 at 12:43
@MarcinOrlowski Could you please point me to the exact answer. I checked this link but couldn't find a solution to my problem. — Arpit Shukla, Aug 28 '22 at 12:45
Are you sure that moshi is working fine with you ? because `@Json(name="start_time")` is enough to achieve what you want — Mohamed Rejeb, Aug 28 '22 at 12:50
Yeah, everything else is working fine, if I rename `startTime` to `start_time` it works as well but I want to stick to Kotlin conventions here. — Arpit Shukla, Aug 28 '22 at 12:51
Can you add the code for retrofit api call and retrofit instance initialization — Mohamed Rejeb, Aug 28 '22 at 12:52

score 2 · Accepted Answer · answered Aug 28 '22 at 13:01

2

1- Add those moshi dependencies:

// Retrofit
implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-moshi:2.9.0'    
// Moshi
implementation 'com.squareup.moshi:moshi-kotlin:1.13.0'
kapt 'com.squareup.moshi:moshi-kotlin-codegen:1.13.0'

2- Change Retrofit Builder to this:

Retrofit.Builder()
    .baseUrl(BASE_URL)
    .addConverterFactory(MoshiConverterFactory.create(
        Moshi.Builder()
            .addLast(KotlinJsonAdapterFactory())
            .build()
    ))
    .build()

This fixed the problem for me.

answered Aug 28 '22 at 13:01

Mohamed Rejeb

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It worked. Thanks! So, does this mean that the `@Json` annotation is useless without all this setup? – Arpit Shukla Aug 28 '22 at 14:16
Well yes, this is the import for @Json `import com.squareup.moshi.Json`so it's part of `com.squareup.moshi:moshi-kotlin` so without this dependency it's useless. `com.squareup.retrofit2:converter-moshi` doesn't contain all moshi features it's just used to link moshi with retrofit. – Mohamed Rejeb Aug 28 '22 at 14:26
@ArpitShukla Kotlin's property doesn't see the annotation. You could do `@property:Json(...)`, but using the codegen is better, anyway. – Eric Cochran Aug 29 '22 at 09:19

How to specify a different name for json key while using Retrofit + Moshi

1 Answers1