Trouble posting json array within a json object with retrofit2

Question

In an api I have to send a JSonArray within a JSonObject. The JSonObject is this:

{
    "token" : "1",
    "task_name" : "Name",
    "task_desc" : "Description",
    "task_start_date" : "2020/10/01",
    "task_end_date" : "2020/10/02",
    "task_award" : "15",
    "child_ids" : [
          {
              "child_id" : "1"
          },
          {
              "child_id" : "2"
          }
      ]
}

When I send this request with Postman, it works fine and the response is receiving in a way I want. But when implementing it in android app, I get an error which says:

retrofit2.adapter.rxjava2.httpexception http 500 internal server error

So it is obvious it's not a server-side bug because it works fine in Postman.

Here is the interface that I use for my api:

interface CreateTaskRemote {

    @FormUrlEncoded
    @POST("parent_create_task")
    fun createTask(
        @Field("token") parentToken: String,
        @Field("task_name") title: String,
        @Field("task_desc") description: String,
        @Field("task_start_date") startDate: String,
        @Field("task_end_date") endDate: String,
        @Field("task_award") award: String,
        @Field("child_ids") childIds: List<ChildId>     <-- here i'm sending array
    ): Single<BooleanResponse>
}

And the ChildId class:

data class ChildId(
    @SerializedName("child_id") val id: Int
)

It seems there is a bug with implementing JSON Array. But I searched a lot on the internet and I couldn't find a solution which works for my situation.

Have you tried logging the json string your sending and to check it's structure? — Muto, Jul 29 '20 at 10:21
@jamesyoung I liked to log it. but how can i log a json which retrofit is generating? — mohammad fakhraee, Jul 29 '20 at 10:30
see this https://stackoverflow.com/questions/21886313/how-to-log-request-and-response-body-with-retrofit-android — Muto, Jul 29 '20 at 10:36

aminography · Accepted Answer · 2020-07-29T10:32:47.247

2

Maybe the cause is that you are posting child_id as an integer value, but you should post it as a string. (Regarding to: "child_id" : "1")

data class ChildId(
    @SerializedName("child_id") val id: String
)

Edit: Try with this configuration too:

data class CreateTaskArgs (
    @SerializedName("token") val token : Int,
    @SerializedName("task_name") val taskName : String,
    @SerializedName("task_desc") val taskDesc : String,
    @SerializedName("task_start_date") val taskStartDate : String,
    @SerializedName("task_end_date") val taskEndDate : String,
    @SerializedName("task_award") val taskAward : Int,
    @SerializedName("child_ids") val childIds : List<ChildId>
)

@POST("parent_create_task")
fun createTask(
    @Body args: CreateTaskArgs
): Single<BooleanResponse>

edited Jul 29 '20 at 10:32

answered Jul 29 '20 at 10:22

aminography

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I changed it to String. but it seems server is converting Int to String. The problem still exist – mohammad fakhraee Jul 29 '20 at 10:26
Am I mistaking in declaring JSon Array inside Json Object? – mohammad fakhraee Jul 29 '20 at 10:28
Try with the `@Body` to send the variables and not using `@FormUrlEncoded`. – aminography Jul 29 '20 at 10:34
I just did it and it work great!! Thank you so much. But can you tell me what is the difference between this two ways? – mohammad fakhraee Jul 29 '20 at 13:11
Parameters in `Post` method carried via the body of the message, so in retrofit, we use this structure with `@Body` to fill the body. – aminography Jul 29 '20 at 18:05

Trouble posting json array within a json object with retrofit2

1 Answers1