# Database
# Introduction
Most web applications use a database. In this section, we are going to see how Goyave applications can query a database, using the awesome Gorm ORM.
Database connections are managed by the framework and are long-lived. When the server shuts down, the database connections are closed automatically. So you don't have to worry about creating, closing or refreshing database connections in your application.
All functions below require the database
and the gorm
packages to be imported.
import (
"github.com/System-Glitch/goyave/v2/database"
"github.com/jinzhu/gorm"
)
# Configuration
Very few code is required to get started with databases. There are some configuration options that you need to change though:
dbConnection
dbHost
dbPort
dbName
dbUsername
dbPassword
dbOptions
dbMaxOpenConnection
dbMaxIdleConnection
dbMaxLifetime
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dbOptions
represents the addtional connection options. For example, when using MySQL, you should use the parseTime=true
option so time.Time
can be handled correctly. Available options differ from one driver to another and can be found in their respective documentation.
# Drivers
The framework supports the following sql drivers:
none
(Disable database features)mysql
postgres
sqlite3
mssql
Change the dbConnection
config entry to the desired driver.
In order to be able connect to the database, Gorm needs a database driver to be imported. Add the following import to your kernel.go
:
import _ "github.com/jinzhu/gorm/dialects/mysql"
// import _ "github.com/jinzhu/gorm/dialects/postgres"
// import _ "github.com/jinzhu/gorm/dialects/sqlite"
// import _ "github.com/jinzhu/gorm/dialects/mssql"
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For SQLite, only the dbName
config entry is required.
# Getting a database connection
# database.GetConnection
Returns the global database connection pool. Creates a new connection pool if no connection is available.
The connections will be closed automatically on server shutdown so you don't need to call Close()
when you're done with the database.
Parameters | Return |
---|---|
*gorm.DB |
Example:
db := database.GetConnection()
db.First(&user)
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Learn how to use the CRUD interface and the query builder in the Gorm documentation.
# database.Close
If you want to manually close the database connection, you can do it using Close()
. New connections can be re-opened using GetConnection()
as usual. This function does nothing if the database connection is already closed or has never been created.
Parameters | Return |
---|---|
void |
Example:
database.Close()
# Models
A model is a structure reflecting a database table structure. An instance of a model is a single database record. Each model is defined in its own file inside the database/model
directory.
# Defining a model
Models are usually just normal Golang structs, basic Go types, or pointers of them. sql.Scanner
and driver.Valuer
interfaces are also supported.
func init() {
database.RegisterModel(&User{})
}
type User struct {
gorm.Model
Name string
Age sql.NullInt64
Birthday *time.Time
Email string `gorm:"type:varchar(100);unique_index"`
Role string `gorm:"size:255"` // set field size to 255
MemberNumber *string `gorm:"unique;not null"` // set member number to unique and not null
Num int `gorm:"AUTO_INCREMENT"` // set num to auto incrementable
Address string `gorm:"index:addr"` // create index with name `addr` for address
IgnoreMe int `gorm:"-"` // ignore this field
}
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All models should be registered in an init()
function inside their model file. To ensure the init()
functions are executed before the server starts, import the models
package in your kernel.go
.
import _ "database/model"
Learn more about model declaration in the Gorm documentation.
# database.RegisterModel
Registers a model for auto-migration.
Parameters | Return |
---|---|
model interface{} | void |
# database.GetRegisteredModels
Get the registered models. The returned slice is a copy of the original, so it cannot be modified.
Parameters | Return |
---|---|
[]interface{} |
# database.ClearRegisteredModels
Unregister all models.
Parameters | Return |
---|---|
void |
# Automatic migrations
If the dbAutoMigrate
config option is set to true, all registered models will be automatically migrated when the server starts.
WARNING
Automatic migrations only create tables, missing columns and missing indexes. They wont't change existing column’s type or delete unused columns.
If you would like to know more about migrations using Gorm, read their documentation.
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