163 lines
4.7 KiB
Markdown
163 lines
4.7 KiB
Markdown
# Models
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<!-- toc -->
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## Model Definition
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```go
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type User struct {
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gorm.Model
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Birthday time.Time
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Age int
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Name string `gorm:"size:255"` // Default size for string is 255, reset it with this tag
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Num int `gorm:"AUTO_INCREMENT"`
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CreditCard CreditCard // One-To-One relationship (has one - use CreditCard's UserID as foreign key)
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Emails []Email // One-To-Many relationship (has many - use Email's UserID as foreign key)
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BillingAddress Address // One-To-One relationship (belongs to - use BillingAddressID as foreign key)
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BillingAddressID sql.NullInt64
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ShippingAddress Address // One-To-One relationship (belongs to - use ShippingAddressID as foreign key)
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ShippingAddressID int
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IgnoreMe int `gorm:"-"` // Ignore this field
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Languages []Language `gorm:"many2many:user_languages;"` // Many-To-Many relationship, 'user_languages' is join table
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}
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type Email struct {
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ID int
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UserID int `gorm:"index"` // Foreign key (belongs to), tag `index` will create index for this column
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Email string `gorm:"type:varchar(100);unique_index"` // `type` set sql type, `unique_index` will create unique index for this column
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Subscribed bool
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}
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type Address struct {
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ID int
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Address1 string `gorm:"not null;unique"` // Set field as not nullable and unique
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Address2 string `gorm:"type:varchar(100);unique"`
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Post sql.NullString `gorm:"not null"`
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}
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type Language struct {
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ID int
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Name string `gorm:"index:idx_name_code"` // Create index with name, and will create combined index if find other fields defined same name
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Code string `gorm:"index:idx_name_code"` // `unique_index` also works
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}
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type CreditCard struct {
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gorm.Model
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UserID uint
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Number string
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}
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```
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## Conventions
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### `gorm.Model` struct
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Base model definition `gorm.Model`, including fields `ID`, `CreatedAt`, `UpdatedAt`, `DeletedAt`, you could embed it in your model, or only write those fields you want
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```go
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// Base Model's definition
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type Model struct {
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ID uint `gorm:"primary_key"`
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CreatedAt time.Time
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UpdatedAt time.Time
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DeletedAt *time.Time
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}
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// Add fields `ID`, `CreatedAt`, `UpdatedAt`, `DeletedAt`
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type User struct {
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gorm.Model
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Name string
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}
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// Only need field `ID`, `CreatedAt`
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type User struct {
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ID uint
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CreatedAt time.Time
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Name string
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}
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```
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### Table name is the pluralized version of struct name
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```go
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type User struct {} // default table name is `users`
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// set User's table name to be `profiles
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func (User) TableName() string {
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return "profiles"
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}
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func (u User) TableName() string {
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if u.Role == "admin" {
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return "admin_users"
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} else {
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return "users"
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}
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}
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// Disable table name's pluralization globally
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db.SingularTable(true) // if set this to true, `User`'s default table name will be `user`, table name setted with `TableName` won't be affected
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```
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### Column name is the snake case of field's name
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```go
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type User struct {
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ID uint // column name will be `id`
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Name string // column name will be `name`
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Birthday time.Time // column name will be `birthday`
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CreatedAt time.Time // column name will be `created_at`
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}
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// Overriding Column Name
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type Animal struct {
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AnimalId int64 `gorm:"column:beast_id"` // set column name to `beast_id`
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Birthday time.Time `gorm:"column:day_of_the_beast"` // set column name to `day_of_the_beast`
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Age int64 `gorm:"column:age_of_the_beast"` // set column name to `age_of_the_beast`
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}
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```
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### Field `ID` as primary key
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```go
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type User struct {
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ID uint // field named `ID` will be the default primary field
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Name string
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}
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// Set a field to be primary field with tag `primary_key`
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type Animal struct {
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AnimalId int64 `gorm:"primary_key"` // set AnimalId to be primary key
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Name string
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Age int64
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}
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```
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### Field `CreatedAt` used to store record's created time
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Create records having `CreatedAt` field will set it to current time.
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```go
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db.Create(&user) // will set `CreatedAt` to current time
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// To change its value, you could use `Update`
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db.Model(&user).Update("CreatedAt", time.Now())
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```
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### Use `UpdatedAt` used to store record's updated time
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Save records having `UpdatedAt` field will set it to current time.
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```go
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db.Save(&user) // will set `UpdatedAt` to current time
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db.Model(&user).Update("name", "jinzhu") // will set `UpdatedAt` to current time
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```
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### Use `DeletedAt` to store record's deleted time if field exists
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Delete records having `DeletedAt` field, it won't be deleted from database, but only set field `DeletedAt`'s value to current time, and the record is not findable when querying, refer [Soft Delete](curd.html#soft-delete)
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