Json Unmarshal Error in POST Request

[cyberkryption]

I am looking for some help. I am building an API with Swagger,Echo and Gorm 2.0

Code for reference at https://github.com/cyberkryption/licence-server

Struct

type Licence struct {
	ID             uint `gorm:"primaryKey"`
	CreatedAt      time.Time
	UpdatedAt      time.Time
	DeletedAt      gorm.DeletedAt `gorm:"index"`
	Licence_holder string         `gorm:"license_holder" json:"License_holder"`
	Licence_type   string         `gorm:"license_type" json:"License_type"`
	Licence_id     string         `gorm:"license_id" json:"License_id"`
	Price          float64        `gorm:"price" json:"Price"`
	Licence_num    uint64         `gorm:"licence_num" json:"Licence_num"`
	Discount       float64        `gorm:"discount" json:"Discount"`
	Validity       uint64         `gorm:"validity" json:"Validity"`
}

Reference request

curl -X 'POST' \
  'http://localhost:8080/api/v1/licence' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
  "Discount": 0,
  "Licence_num": 0,
  "License_holder": "cyberkryption",
  "License_id": "1234",
  "License_type": "test",
  "Price": 20.00,
  "Validity": 365,
  "createdAt": "2022-01-30T08:25:36.8471179Z",
  "deletedAt": {
    "time": "2022-01-30T08:25:36.8471179Z",
    "valid": true
  },
  "id": 0,
  "updatedAt": "2022-01-30T08:25:36.8471179Z"
}'

When I try to bind to the body in the POST request at

I get an json unmarshall error shown below

{
  "message": "json: Unmarshal(non-pointer model.Licence)"
}

Interestingly, the swagger api seems to think it is a string?

Can anyone help me understand this please? Is there a problem with my structs in model.go or swagger spec?

[aldas]

I did not test but gorm.DeletedAt has UnmarshalJSON which can handle unmarshalling. so your request probably should be

curl -X 'POST' \
  'http://localhost:8080/api/v1/licence' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
  "Discount": 0,
  "Licence_num": 0,
  "License_holder": "cyberkryption",
  "License_id": "1234",
  "License_type": "test",
  "Price": 20.00,
  "Validity": 365,
  "createdAt": "2022-01-30T08:25:36.8471179Z",
  "deletedAt":  "2022-01-30T08:25:36.8471179Z",
  "id": 0,
  "updatedAt": "2022-01-30T08:25:36.8471179Z"
}'

and you body needs to be pointer. so use

if err := (&echo.DefaultBinder{}).BindBody(c, &body); err != nil {

[cyberkryption]

I wouild like to have the same naming style but there are constraints. For example, gorm by default will use snake_case and will convert Licence_holder to licence_holder in sqlite. If I go all snake case in my structs then they are not exportable from the models package to the api package as they statr with a lowercase letter.Hence, that is why I have a mixture of cases. Is there something I am not understanding.

[aldas]

add json struct tag json:"fieldname" to all fields. https://pkg.go.dev/encoding/json has documentation about struct tags and json

[cyberkryption]

I have removed gorm and unified my structs and json. JSON body decoding now works.
It looks to be some sort of issue with gorm / json structs. Will probably look at sqlx for db stuffor just do database/sql to get working. I can revisit ORM later

[cyberkryption]

I have refactored code and want to use a global variable for DB. Unmarshalling problem related GORM so will use database/sql for now. I have one problem, I have declared DB as a global variable in the api package and when iti is referenced in main.go, I can see the database object in VS code.

However , if line 60 is not present in licence.go then the database/sql DB object is nil and I get a pointer def reference on line 72. If I uncomment line 60/72 , the function works correctly. I dont want to connect and close on each api call, so why is my DB not global in api package?

Refernces
https://github.com/cyberkryption/licence-server/blob/main/api/licence.go
https://github.com/cyberkryption/licence-server/blob/main/api/api.go

Any Help appreciated

[cyberkryption]

I have solved my issue for global datbase by using receiver functions in licence.go and using a BaseHandler function similiar to https://techinscribed.com/different-approaches-to-pass-database-connection-into-controllers-in-golang/

Code is on github