a better way than ```val tuples = receiveText() ...

# codereview

[elect]

a better way than

val tuples = receiveText()
    .drop(1).dropLast(1)
    .split(',')
    .map { it.substringBefore(':') to it.substringAfter(':') }

to transform something like this

{"event_type":"pre-commit","event_time":"2024-02-15T095148Z","action_name":"Dataset","hook_id":"dataset_validator","repository_id":"quickstart","branch_id":"main","source_ref":"main","commit_message":"asd","committer":"quickstart"}

into a List<Pair<String, String>>?

[hho]

Yes, use a proper JSON parser (❗) and iterate object properties to get the list of pairs.
For example, if any of your values contains a ,, your code would break. Using a real parser fixes that.

[elect]

I'd like to use camel case named fields, enums, `Instant`s and custom transformations

[Shawn]

I don't understand how that's a response to what Henning said—any decent JSON library can be configured to do all of that

[Shawn]

in fact, I have done literally all of what you've asked for with Jackson in Java

[elect]

I believe you, but for my use case (some quick prototyping) I think it's overkill, I managed to parse it properly into a Class in 19 lines in few minutes of coding

[elect]

ok, polishing phase now, I'll give a JSON parser a try

[elect]

@Shawn how did you conditionally parse specific fields?
I need to parse branchId only if eventType is not a specific enum

[elect]

@hho do you happen to have any idea about conditional deserialization?

[hho]

What do you want to achieve?
For your List of Strings you can just do something like this:

import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.module.kotlin.readValue

val json = ObjectMapper().findAndRegisterModules()

fun parseJson(input: String): List<Pair<String, String>> {
    val parsed = json.readValue<MutableMap<String,String>>(input)

    if (parsed["event_type"] != "pre-commit") { // whatever your condition here
        parsed.remove("branch_id")
    }

    return parsed.toList()
}

fun main() {
    println(parseJson("""{"event_type":"pre-commit","event_time":"2024-02-15T09:51:48Z","action_name":"Dataset","hook_id":"dataset_validator","repository_id":"quickstart","branch_id":"main","source_ref":"main","commit_message":"asd","committer":"quickstart"}"""))
}

(that is with jackson-databind and jackson-module-kotlin on the classpath).

However, what you're describing sounds more like you have different event_types which should be deserialized into different types in your app as well. With Jackson, that could look something like this:

import com.fasterxml.jackson.annotation.JsonSubTypes
import com.fasterxml.jackson.annotation.JsonTypeInfo
import <http://com.fasterxml.jackson.annotation.JsonTypeInfo.As|com.fasterxml.jackson.annotation.JsonTypeInfo.As>
import com.fasterxml.jackson.databind.ObjectMapper
import com.fasterxml.jackson.module.kotlin.readValue

val json = ObjectMapper().findAndRegisterModules()

fun parseJson(input: String): BaseEvent {
    return json.readValue(input)
}

fun main() {
    println(parseJson("""{"event_type":"pre-commit","event_time":"2024-02-15T09:51:48Z","action_name":"Dataset","hook_id":"dataset_validator","repository_id":"quickstart","branch_id":"main","source_ref":"main","commit_message":"asd","committer":"quickstart"}"""))
    println(parseJson("""{"event_type":"something-else","event_time":"2024-02-15T09:51:48Z","action_name":"Foo","hook_id":"Bar","some_other_field":"Baz"}"""))
}

@JsonTypeInfo(include = As.PROPERTY, property = "event_type", use = JsonTypeInfo.Id.NAME)
@JsonSubTypes(
    JsonSubTypes.Type(value = PreCommitEvent::class, name = "pre-commit"),
    JsonSubTypes.Type(value = SomeOtherEvent::class, name = "something-else")
)
interface BaseEvent {
    val event_time: String
    val action_name: String
    val hook_id: String
}

data class PreCommitEvent(
    override val event_time: String,
    override val action_name: String,
    override val hook_id: String,
    val repository_id: String,
    val branch_id: String,
    val source_ref: String,
    val commit_message: String,
    val committer: String
) : BaseEvent

data class SomeOtherEvent(
    override val event_time: String,
    override val action_name: String,
    override val hook_id: String,
    val some_other_field: String
) : BaseEvent

[elect]

{
  "event_type": "pre-merge",
  "event_time": "2021-02-28T14:03:31Z",
  "action_name": "test action",
  "hook_id": "prevent_user_columns",
  "repository_id": "repo1",
  "branch_id": "feature-1",
  "source_ref": "feature-1",
  "commit_message": "merge commit message",
  "committer": "committer",
  "commit_metadata": {
    "key": "value"
  }
}

I don't want to deserialize branch_id (because it won't be there and it should be null in the corresponding class) if event_type is a specific value(s)
https://docs.lakefs.io/howto/hooks/webhooks.html#request-body-schema

[Shawn]

I meant to reply to this a week ago, but Jackson can be configured to deserialize missing properties as null, so you don't really need to switch on event_type

[elect]

I need essentially conditional deserialization
the only way to achieve that I found so far, is to write your own Serializer (which actually defy the point of using a JSON parser in the first place)

[Shawn]

why do you need it to be conditional? do you ever expect that data to be present even when event_type is one of those specific values?

[elect]

according to the docs no, but I'd like to enforce that at priori

[elect]

also, I had encountered other user cases in the past where I needed exactly that, so I'd like to achieve that, if possible