gorm read json from interface type of model

I have a model as

type FlowTransaction struct {
	gorm.Model
	Name                          string
	PartnerTransactionReferenceId string
	ReconData                     interface{} `gorm:"type:jsonb"`
	DestinationAccountNumber      *string
	DestinationIfsc               *string
	Amount                        uint64
	PartnerId                     uint
	FlowId                        uint
	SelfSettle                    bool
	IsSandbox                     bool
}

while reading from my postgres database, in my ReconData I am getting message as unreadable could not resolve interface type. I tried implementing scan and value methods.

type customJson interface{}

func (j *customJson) Scan(value interface{}) error {
	return Scan(value, j)
}

func (j customJson) Value() (driver.Value, error) {
	return Value(j)
}


func Scan[dtoType any](value interface{}, model *dtoType) error {
	bytes, ok := value.([]byte)
	if !ok {
		return errors.New(fmt.Sprint("Failed to unmarshal JSONB value:", value))
	}

	err := json.Unmarshal(bytes, model)
	return err
}

func Value[dtoType any](j dtoType) ([]byte, error) {
	return json.Marshal(j)
}

but it is giving an error as invalid receiver type customJson (pointer or interface type). Do you guys have any idea how can I go about solving this. Any help is appreciated.

Because gorm use pgx, you can use pgtype package. there's type JSONB

So your model look like this

import (
	...
	"github.com/jackc/pgtype"
	...
)

type FlowTransaction struct {
	gorm.Model
	Name                          string
	PartnerTransactionReferenceId string
	ReconData                     pgtype.JSONB `gorm:"type:jsonb"`
	DestinationAccountNumber      *string
	DestinationIfsc               *string
	Amount                        uint64
	PartnerId                     uint
	FlowId                        uint
	SelfSettle                    bool
	IsSandbox                     bool
}

Define the JSON type.

import (
	"database/sql/driver"
	"encoding/json"
	"errors"
	"fmt"
)

type JSON json.RawMessage

func (j *JSON) Scan(value interface{}) error {
	bytes, ok := value.([]byte)
	if !ok {
		return errors.New(fmt.Sprint("Failed to unmarshal JSONB value:", value))
	}

	result := json.RawMessage{}
	err := json.Unmarshal(bytes, &result)
	*j = JSON(result)
	return err
}

func (j JSON) Value() (driver.Value, error) {
	if len(j) == 0 {
		return nil, nil
	}
	return json.RawMessage(j).MarshalJSON()
}

and in model struct :

type FlowTransaction struct {
    gorm.Model
    Name                          string
    PartnerTransactionReferenceId string
    ReconData                     JSON `type:jsonb`
    DestinationAccountNumber      *string
    DestinationIfsc               *string
    Amount                        uint64
    PartnerId                     uint
    FlowId                        uint
    SelfSettle                    bool
    IsSandbox                     bool
}