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Version: 1.16.x

自定义回调处理是最常见的接口开发实现,我们往往只需要对接口中的部分实现进行替换修改,以在原有的实现逻辑中注入自定义的逻辑实现。我们来看一个自定义回调处理的示例,我们需要将所有执行的 SQL 语句记录到 monitor 表中,以方便于进行 SQL 审计。

为简化示例编写,我们这里实现了一个自定义的 MySQL 驱动,该驱动继承于 gdb 模块中已经实现的 DriverMysql,并按照需要修改覆盖相应的接口方法。由于所有的 SQL 语句执行必定会通过 DoQuery 或者 DoExec 接口,因此我们在自定义的驱动中实现并覆盖这两个接口方法即可。

package driver

import (
"context"
"database/sql"
"github.com/gogf/gf/database/gdb"
"github.com/gogf/gf/os/gtime"
)

// MyDriver is a custom database driver, which is used for testing only.
// For simplifying the unit testing case purpose, MyDriver struct inherits the mysql driver
// gdb.DriverMysql and overwrites its functions DoQuery and DoExec.
// So if there's any sql execution, it goes through MyDriver.DoQuery/MyDriver.DoExec firstly
// and then gdb.DriverMysql.DoQuery/gdb.DriverMysql.DoExec.
// You can call it sql "HOOK" or "HiJack" as your will.
type MyDriver struct {
*gdb.DriverMysql
}

var (
// customDriverName is my driver name, which is used for registering.
customDriverName = "MyDriver"
)

func init() {
// It here registers my custom driver in package initialization function "init".
// You can later use this type in the database configuration.
if err := gdb.Register(customDriverName, &MyDriver{}); err != nil {
panic(err)
}
}

// New creates and returns a database object for mysql.
// It implements the interface of gdb.Driver for extra database driver installation.
func (d *MyDriver) New(core *gdb.Core, node *gdb.ConfigNode) (gdb.DB, error) {
return &MyDriver{
&gdb.DriverMysql{
Core: core,
},
}, nil
}

// DoQuery commits the sql string and its arguments to underlying driver
// through given link object and returns the execution result.
func (d *MyDriver) DoQuery(ctx context.Context, link gdb.Link, sql string, args ...interface{}) (rows *sql.Rows, err error) {
tsMilli := gtime.TimestampMilli()
rows, err = d.DriverMysql.DoQuery(ctx, link, sql, args...)
link.Exec(
"INSERT INTO `monitor`(`sql`,`cost`,`time`,`error`) VALUES(?,?,?,?)",
gdb.FormatSqlWithArgs(sql, args),
gtime.TimestampMilli()-tsMilli,
gtime.Now(),
err,
)
return
}

// DoExec commits the query string and its arguments to underlying driver
// through given link object and returns the execution result.
func (d *MyDriver) DoExec(ctx context.Context, link gdb.Link, sql string, args ...interface{}) (result sql.Result, err error) {
tsMilli := gtime.TimestampMilli()
result, err = d.DriverMysql.DoExec(ctx, link, sql, args...)
link.Exec(
"INSERT INTO `monitor`(`sql`,`cost`,`time`,`error`) VALUES(?,?,?,?)",
gdb.FormatSqlWithArgs(sql, args),
gtime.TimestampMilli()-tsMilli,
gtime.Now(),
err,
)
return
}

我们看到,这里在包初始化方法 init 中使用了 gdb.Register("MyDriver", &MyDriver{}) 来注册了了一个自定义名称的驱动。我们也可以通过 gdb.Register("mysql", &MyDriver{}) 来覆盖已有的框架 mysql 驱动为自己的驱动。

驱动名称 mysql 为框架默认的 DriverMysql 驱动的名称。

由于这里我们使用了一个新的驱动名称 MyDriver,因此在 gdb 配置中的 type 数据库类型时,需要填写该驱动名称。以下是一个使用配置的示例:

[database]
type = "MyDriver"
link = "root:12345678@tcp(127.0.0.1:3306)/test"