Jsonb codec

[go-aegian]

using v5 now the jsonb scan has changed somehow and I need to get help how to scan a marshalled json value into a struct field of type jsonbcodec, below is an example of what I'm trying to do in order to assign to jsonbcodec field a json value, but it does not work, so something for sure I'm doing wrong and need your help understanding the new api.

import "github.com/jackc/pgx/v5/pgtype"

type Example struct {
Field pgtype.JSONBCodec `json:"field"`
}

type Custom struct {
Field1 string `json:"field1"`
Field2 string `json:"field2"`
}

a := []Custom {
{
Field1: "test1",
Field2: "test2" ,
},
}

marshalledA, _:= json.Marshal(a)

example:=&Example{}

m:=pgtype.NewMap()
err:=pgtype.JSONBCodec{}.PlanScan(m, pgtype.JSONBArrayOID, pgx.TextFormatCode, &example.Field).Scan(marshalledA, &example.Field)

fmt.Println(err)

[jackc]

You don't use JSONBCodec as a scan target. You should scan into the type you want the JSON unmarshalled into or scan into a []byte or string to get the raw data.

[go-aegian]

So in the example how will it be done?

[jackc]

Scan into whatever type of value you actually want -- not a JSONBCodec.

[go-aegian]

Not sure what do you mean when the jsoncodec field provides planscan, decodevalue but there is no way to assign it back to a []byte variable.

Here is a test example that won't even compile as following what you said

import (
"context"
"encoding/json"
"fmt"
"testing"

    "github.com/jackc/pgx/v5"
"github.com/jackc/pgx/v5/pgtype"

)

type Example struct {
Field pgtype.JSONBCodec json:"field"
}

type Custom struct {
Field1 string json:"field1"
Field2 string json:"field2"
}

func TestJSONCodec(tst *testing.T) {
a := []Custom {
{
Field1: "test1",
Field2: "test2" ,
},
}
jsonBytes, _ := json.Marshal(a)

t := &Example{}
err := t.Field.PlanScan(pgtype.NewMap(), pgtype.JSONBOID, pgx.TextFormatCode, &t.Field).Scan(jsonBytes, &t.Field)
fmt.Println(err)

var decoded []byte
err = t.Field.PlanScan(pgtype.NewMap(), pgtype.JSONBOID, pgx.TextFormatCode, &decoded).Scan(t.Field, &decoded)
fmt.Println(err)

}

[jackc]

You should almost never need to directly use JSONBCodec or any other Codec for that matter. I'm not sure why you're scanning outside of the context of a database query, but if that's what you really need then you probably want to use https://pkg.go.dev/github.com/jackc/pgx/[email protected]/pgtype#Map.Scan.