feat(docs): Adding docs on how to use the package (#6)

* Adding docs on how to use the package

* Updated examples

* Updated examples

README.md

@@ -1,3 +1,97 @@
 # Patcher
 
-Patcher is a GO library that provides a simple way to generate and SQL patches from structs.
+Patcher is a GO library that provides a simple way to generate and SQL patches from structs. The library was built out
+of the need to generate patches for a database; when a new field is added to a struct, this would result in a bunch of
+new `if` checks to be created in the codebase. This library aims to solve that problem by generating the SQL patches for
+you.
+
+## Usage
+
+To use the library, you need to create a struct that represents the table you want to generate patches for. The struct
+should have the following tags:
+
+- `db:"column_name"`: This tag is used to specify the column name in the database.
+
+Example:
+
+```go
+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"`
+}
+
+type PersonWhere struct {
+	ID *int `db:"id"`
+}
+
+func NewPersonWhere(id int) *PersonWhere {
+	return &PersonWhere{
+		ID: &id,
+	}
+}
+
+func (p *PersonWhere) Where() (string, []any) {
+	return "id = ?", []any{*p.ID}
+}
+
+func main() {
+	const jsonStr = `{"name": "John", "age": 25}`
+
+	person := new(Person)
+	if err := json.Unmarshal([]byte(jsonStr), person); err != nil {
+		panic(err)
+	}
+
+	condition := NewPersonWhere(1)
+
+	sqlStr, args, err := patcher.GenerateSQL(
+		person,
+		patcher.WithTable("people"),
+		patcher.WithWhere(condition),
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Println(sqlStr)
+	fmt.Println(args)
+}
+```
+
+This will output:
+
+```sql
+UPDATE people
+SET name = ?,
+    age  = ?
+WHERE 1
+  AND id = ?
+```
+
+with the args:
+
+```
+["John", 25, 1]
+```
+
+### Joins
+
+To generate a join, you need to create a struct that represents the join. This struct should implement
+the [Joiner](./joiner.go) interface.
+
+Once you have the join struct, you can pass it to the `GenerateSQL` function using the `WithJoin` option. You can add as
+many of these as you would like.
+
+# Examples
+
+You can find examples of how to use this library in the [examples](./examples) directory.

examples/basic/basic.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+
+	"github.com/Jacobbrewer1/patcher"
+)
+
+type Person struct {
+	ID   *int    `db:"id"`
+	Name *string `db:"name"`
+}
+
+type PersonWhere struct {
+	ID *int `db:"id"`
+}
+
+func NewPersonWhere(id int) *PersonWhere {
+	return &PersonWhere{
+		ID: &id,
+	}
+}
+
+func (p *PersonWhere) Where() (string, []any) {
+	return "id = ?", []any{*p.ID}
+}
+
+func main() {
+	const jsonStr = `{"id": 1, "name": "john"}`
+
+	person := new(Person)
+	if err := json.Unmarshal([]byte(jsonStr), person); err != nil {
+		panic(err)
+	}
+
+	condition := NewPersonWhere(*person.ID)
+
+	sqlStr, args, err := patcher.GenerateSQL(
+		person,
+		patcher.WithTable("people"),
+		patcher.WithWhere(condition),
+	)
+	if err != nil {
+		panic(err)
+	}
+
+	fmt.Println(sqlStr)
+	fmt.Println(args)
+}

examples/joiner/README.md

@@ -0,0 +1,190 @@
+# 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.
+
+```go
+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)
+}
+
+```
+
+```go
+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)
+}
+
+```