iamgoangle / go-json-bson-tutorial

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go-json-bson-tutorial

---

Omitempty State

common case

type User struct {
	Firstname	string   `json:"firstname,omitempty"`
	IsActive  bool    `json:"is_active,omitempty"`
}

Field	Value	Actual Result
Firstname	&User{}	{}
Firstname	&User {Firstname: ""}	{}
Firstname	&User {Firstname: "golf"}	{"firstname": "golf"}
Firstname	&User{Firstname: "golf", IsActive: true}	{"firstname": "golf", "is_active": true}
Firstname	&User{Firstname: "golf", IsActive: false}	{"firstname": "golf"}

---

Simulate User Request Payload

---

User: Checked IsActive

&User{
	Firstname: "golf",
	IsActive:  true,
}

// output
{"firstname":"golf","IsActive":true}

---

User: Unchecked IsActive

In this case you will see that your field is_active is missing. Since omitempty will ignore you field once reach zero-value.

A value of bool type has 2 possible values: false and true. And you want to "communicate" 3 different states with a bool field, namely to not update the field, to set the field to false and to set the field to true. This is obviously not possible.

&User{
	Firstname: "golf",
	IsActive:  false,
}

// output
{"firstname":"golf"}

---

To solve above case

Add pointer to your type

type User struct {
	Firstname string   `json:"firstname,omitempty"`
	IsActive  *bool    `json:"is_active,omitempty"`
}

---

true case

isActive := true
&User{
	Firstname: "golf",
	IsActive:  &isActive,
}

// output
{"firstname":"golf","is_active":true}

---

false case

isActive := false
&User{
	Firstname: "golf",
	IsActive:  &isActive,
}

// output
{"firstname":"golf","is_active":false}

---

zero value case

hit omitempty

&User{
	Firstname: "golf",
}

// output
{"firstname":"golf"}

---

omitempty tag

The purpose of omitempty tag is ignoring empty field.

bson

You need to understand bson type cleary form https://www.mongodb.com/docs/drivers/go/current/fundamentals/bson/ And also learn more once apply to mongodb repository https://www.mongodb.com/blog/post/mongodb-go-driver-tutorial-part-1-connecting-using-bson-and-crud-operations