Kotlin Client for PostgREST

Kotlin JVM client for PostgREST

Installation

Maven

<dependency>
    <groupId>io.supabase</groupId>
    <artifactId>postgrest-kt</artifactId>
    <version>{version}</version>
    <type>pom</type>
</dependency>

Gradle

implementation 'io.supabase:postgrest-kt:{version}'

Usage

Initializing the client

val postgrestClient =  PostgrestDefaultClient(
    uri = URI("http://localhost:3111"),
    headers = mapOf("Authorization" to "foobar")
)

You can also pass in a custom schema using the schema parameter.

Entry points

There are two methods to start any call on the PostgresClient.

from

The from<T> function is used for querying. It takes a generic parameter to allow for auto-completion when defining column names. However, you can always use Any if you are unsure about the data type.

postgresClient.from<Any>("messages")
    .select()
    .neq("content", "abc")
    .execute()

postgresClient.from<Message>("messages")
    .select()
    .neq(Message::content, "abc")
    .execute()

rpc

The rpc<T> function executes a stored procedure.

postgresClient.rpc("get_status", mapOf("foo" to "bar"))
    .execute()

Executing requests

There are three ways to execute requests and read the response.

execute

The execute method returns a PostgrestHttpResponse. The HttpResponse contains the status code, body as string and the count (if you request the count).

val response = postgresClient.from<Any>("messages")
    .select()
    .execute()

println(response.body)
println(response.status)
println(response.count)

executeAndGetSingle

The executeAndGetSingle<T> function returns T. The JSON converter is used to convert the response to the DTO.

data class Message(
    val id: Long,
    val content: String
)

val message = postgresClient.from<Message>("messages")
    .select()
    .eq(Message::id, 123L)
    .limit(1)
    .single()
    .executeAndGetSingle<Message>()

println(message.content)

You can also use this function to convert your data to a Map, rather than a separate DTO.

val message = postgresClient.from<Message>("messages")
    .select()
    .eq(Message::id, 123L)
    .limit(1)
    .single()
    .executeAndGetSingle<Map<String, Any>>()

println(message["content"])

executeAndGetList

The executeAndGetList<T> function is pretty much the same as the executeAndGetSingle<T> function, however, this functions returns a list of T.

val messages = postgresClient.from<Any>("messages")
    .select()
    .executeAndGetList<Message>()

messages.forEach { message ->
    println(messege.content)
}

CRUD

Selecting data

The select function is used for selecting data.

val response = postgresClient.from<Any>("messages")
    .select(count = Count.EXACT) // will allow accessing data AND count
    .eq("content", "foobar")
    .execute()

Inserting data

The insert function is used for inserting or upserting data.

val message = Message(
    id = 123L,
    content = "foobar"
)

val response = postgresClient.from<Message>("messages")
    .insert(message)
    .execute()

val response = postgresClient.from<Any>("messages")
    .insert(
        value = mapOf("id" to 123L, "content" to "foobar"),
        upsert = true
    )

Updating data

The update function is used for updating data.

val response = postgresClient.from<Any>("messages")
    .update(mapOf("content" to "hello"))
    .eq("id", 123L)
    .execute()

Deleting data

The delete function is used for deleting data.

val response = postgresClient.from<Any>("messages")
    .delete()
    .eq("id", 123L)
    .execute()

HTTP / (De)-Serialization

The Apache Http-Client (5.x) is used for executing HTTP calls, Jackson is used to convert responses to DTOs.

If you want to change that, you need to implement the PostgrestHttpClient and the PostgrestJsonConverter interface.

See PostgrestHttpClientApache and PostgrestsonConverterJackson.

val postgrestClient = PostgrestClient(
    httpClient = customHttpClient(),
    jsonConverter = customConverter()
)

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