How do I insert JSON into a postgres table using Anorm? - postgresql

Question

I'm getting a runtime exception when trying to insert a JSON string into a JSON column. The string I have looks like """{"Events": []}""", the table has a column defined as status JSONB NOT NULL. I can insert the string into the table from the command line no problem. I've defined a method to do the insert as:
import play.api.libs.json._
import anorm._
import anorm.postgresql._
def createStatus(
status: String,
created: LocalDateTime = LocalDateTime.now())(implicit c: SQLConnection): Unit = {
SQL(s"""
|INSERT INTO status_feed
| (status, created)
|VALUES
| ({status}, {created})
|""".stripMargin)
.on(
'status -> Json.parse("{}"), // n.b. would be Json.parse(status) but this provides a concise error message
'created -> created)
.execute()
}
and calling it gives the following error:
TypeDoesNotMatch(Cannot convert {}: org.postgresql.util.PGobject to String for column ColumnName(status_feed.status,Some(status)))
anorm.AnormException: TypeDoesNotMatch(Cannot convert {}: org.postgresql.util.PGobject to String for column ColumnName(status_feed.status,Some(status)))
I've done loads of searching for this issue but there's nothing about this specific use case that I could find - most of it is pulling out json columns into case classes. I've tried slightly different formats using spray-json's JsValue, play's JsValue, simply passing the string as-is and casting in the query with ::JSONB and they all give the same error.
Update: here is the SQL which created the table:
CREATE TABLE status_feed (
id SERIAL PRIMARY KEY,
status JSONB NOT NULL,
created TIMESTAMP WITHOUT TIME ZONE NOT NULL DEFAULT NOW()
)

Answer 1

The error is not on values given to .executeInsert, but on the parsing of the INSERT result (inserted key).
import java.sql._
// postgres=# CREATE TABLE test(foo JSONB NOT NULL);
val jdbcUrl = "jdbc:postgresql://localhost:32769/postgres"
val props = new java.util.Properties()
props.setProperty("user", "postgres")
props.setProperty("password", "mysecretpassword")
implicit val con = DriverManager.getConnection(jdbcUrl, props)
import anorm._, postgresql._
import play.api.libs.json._
SQL"""INSERT INTO test(foo) VALUES(${Json.obj("foo" -> 1)})""".
executeInsert(SqlParser.scalar[JsValue].singleOpt)
// Option[play.api.libs.json.JsValue] = Some({"foo":1})
/*
postgres=# SELECT * FROM test ;
foo
------------
{"foo": 1}
*/
BTW, the plain string interpolation is useless.

Answer 2

Turns out cchantep was right, it was the parser I was using. The test framework I am using swallowed the stack trace and I assumed the problem was on the insert, but what's actually blowing up is the next line in the test where I use the parser.
The case class and parser were defined as:
case class StatusFeed(
status: String,
created: LocalDateTime) {
val ItemsStatus: Status = status.parseJson.convertTo[Status]
}
object StatusFeed extends DefaultJsonProtocol {
val fields: String = sqlFields[StatusFeed]() // helper function that results in "created, status"
// used in SQL as RETURNING ${StatusFeed.fields}
val parser: RowParser[StatusFeed] =
Macro.namedParser[StatusFeed](Macro.ColumnNaming.SnakeCase)
// json formatter for Status
}
As defined the parser attempts to read a JSONB column from the result set into the String status. Changing fields to val fields: String = "created, status::TEXT" resolves the issue, though the cast may be expensive. Alternatively, defining status as a JsValue instead of a String and providing an implicit for anorm (adapted from this answer to use spray-json) fixes the issue:
implicit def columnToJsValue: Column[JsValue] = anorm.Column.nonNull[JsValue] { (value, meta) =>
val MetaDataItem(qualified, nullable, clazz) = meta
value match {
case json: org.postgresql.util.PGobject => Right(json.getValue.parseJson)
case _ =>
Left(TypeDoesNotMatch(
s"Cannot convert $value: ${value.asInstanceOf[AnyRef].getClass} to Json for column $qualified"))
}
}