Joiner

For this example assume that you have two tables in the database people and contacts.

People

id	name	age
1	Ben	25
2	John	30

Contacts

id	person_id	email
1	1	[email protected]
2	2	[email protected]

Example

Moving forwards with the example, lets assume that you are updating the person and you have received their email as the key on the data. You can use the Joiner interface to join the two tables and update the person.

package main

import (
	"encoding/json"
	"fmt"

	"github.com/jacobbrewer1/patcher"
)

type Person struct {
	ID    *int    `db:"id"`
	Name  *string `db:"name"`
	Age   *int    `db:"age"`
	Email *string `db:"email"`
}

type PersonWhere struct {
	ID *int
}

func NewPersonWhere(id int) *PersonWhere {
	return &PersonWhere{
		ID: &id,
	}
}

func (p *PersonWhere) Where() (string, []interface{}) {
	return "id = ?", []interface{}{*p.ID}
}

type ContactWhere struct {
	Email *string
}

func NewContactWhere(email string) *ContactWhere {
	return &ContactWhere{
		Email: &email,
	}
}

func (c *ContactWhere) Where() (string, []interface{}) {
	return "email = ?", []interface{}{*c.Email}
}

type PersonContactJoiner struct{}

func NewPersonContactJoiner() *PersonContactJoiner {
	return &PersonContactJoiner{}
}

func (p *PersonContactJoiner) Join() (string, []any) {
	return "JOIN contacts c ON c.person_id = p.id", nil
}

func main() {
	jsonStr := `{"name": "john", "age": 25, "email": "[email protected]"}`

	person := new(Person)
	if err := json.Unmarshal([]byte(jsonStr), person); err != nil {
		panic(err)
	}

	condition := NewPersonWhere(1)
	joiner := NewPersonContactJoiner()

	sqlStr, args, err := patcher.GenerateSQL(
		person,
		patcher.WithTable("people"),
		patcher.WithWhere(condition),
		patcher.WithJoin(joiner),
	)
	if err != nil {
		panic(err)
	}

	fmt.Println(sqlStr)
	fmt.Println(args)
}

package main

import (
	"encoding/json"
	"fmt"

	"github.com/jacobbrewer1/patcher"
)

type Person struct {
	ID    *int    `db:"id"`
	Name  *string `db:"name"`
	Age   *int    `db:"age"`
	Email *string `db:"email"`
}

type PersonWhere struct {
	ID *int `db:"id"`
}

func NewPersonWhere(id int) *PersonWhere {
	return &PersonWhere{
		ID: &id,
	}
}

func (p *PersonWhere) Where() (string, []interface{}) {
	return "id = ?", []interface{}{*p.ID}
}

type ContactWhere struct {
	Email *string
}

func NewContactWhere(email string) *ContactWhere {
	return &ContactWhere{
		Email: &email,
	}
}

func (c *ContactWhere) Where() (string, []interface{}) {
	return "email = ?", []interface{}{*c.Email}
}

type PersonContactJoiner struct {
	Email *string
}

func NewPersonContactJoiner(email string) *PersonContactJoiner {
	return &PersonContactJoiner{
		Email: &email,
	}
}

func (p *PersonContactJoiner) Join() (string, []any) {
	return "JOIN contacts c ON c.person_id = p.id AND c.email = ?", []any{*p.Email}
}

func main() {
	jsonStr := `{"name": "john", "age": 25, "email": "[email protected]"}`

	person := new(Person)
	if err := json.Unmarshal([]byte(jsonStr), person); err != nil {
		panic(err)
	}

	condition := NewPersonWhere(1)
	joiner := NewPersonContactJoiner(*person.Email)

	sqlStr, args, err := patcher.GenerateSQL(
		person,
		patcher.WithTable("people"),
		patcher.WithWhere(condition),
		patcher.WithJoin(joiner),
	)
	if err != nil {
		panic(err)
	}

	fmt.Println(sqlStr)
	fmt.Println(args)
}