I've got a question about deserializing a response that contains a column that is of type `json` ``...

# supabase-kt

[Colton Idle]

I've got a question about deserializing a response that contains a column that is of type json

@Serializable
class Config(
    val type: String = "abc",
    val config: String = "", //this is json in postgres
)

If I try to select a config then I get this

kotlinx.serialization.json.internal.JsonDecodingException: Unexpected JSON token at offset 83: Expected beginning of the string, but got { at path: $[0].config

I kinda figured that the postgres json is just a string. Do I need to set it as something else?

[Colton Idle]

Hm. Changing Config to

@Serializable
class Config(
    val type: String = "abc",
    val config: JsonElement //this is json in postgres
)

worked. Honestly a little surprised as I could've sworn that when I worked with other apis that stuffed json into an api response for a specific field. id get a string back. I wonder what actually comes over the wire. anyway. wont worry about it now. but if anyone wants to shine some light on this ill take it.

[Jan]

The json type does send the data as actual JSON. So if you have a json object in your row, then it will be a JsonObject. Otherwise you'd just have a text column.
So you can just use a generic JsonElement as your type or more precise a JsonObject or even a custom data class.

[Colton Idle]

Very interesting...
how does it send actual json if the response is already json?
unless its not json? i guess ill try to use a proxy to inspect.

And cool. I'll move to using a JsonObject... but I might consider just changing the field to text. 😃

[Jan]

You can print out the response data from PostgrestResult#data .

[Colton Idle]

nice. thank you! TIL

[Colton Idle]

wait. so how do i insert json data?

[Jan]

If you have a table test with a json column example , just do something like this:

@Serializable
data class Test(val example: JsonObject)

val toInsert = Test(buildJsonObject {
   put("key", "value")
})
supabase.from("test").insert(toInsert)

Or if the data in your json column is always following the same scheme, you can also use a custom data type:

@Serializable
data class Test(val example: MyDataType) 

@Serializable
data class MyDataType(val key: String)

val toInsert = Test(MyDataType("value"))
supabase.from("test").insert(toInsert)

[Jan]

Actually, there is also a documentation entry for that

[Colton Idle]

Interesting! thanks! I ended up using JsonElement for now and then

Json.encodeToJsonElement(myObjectThatShouldBeConvertedToJson)

[Colton Idle]

ah. and here i was looking at the kotlin docs page directly

[Jan]

Yea, the reference docs only document the methods etc. For Supabase/Postgres specific stuff, the main documentation shows a lot of examples and snippets

[Colton Idle]

didn't know that either. will make sure to do that. thank you!