A beginner’s question about creating database connections.

[gzlboy]

我看到bookstore示例代码这样写

type ServiceContext struct {
	c     config.Config
	Model model.BookModel
}

func NewServiceContext(c config.Config) *ServiceContext {
	return &ServiceContext{
		c:     c,
		Model: model.NewBookModel(sqlx.NewMysql(c.DataSource), c.Cache),
	}
}

把model放入ServiceContext 里面，如果项目有几十上百个model，都写在这里显得很臃肿，不知道会有性能问题吗？
另外我跟进sqlx.NewMysql方法看，好像使用了数据库连接池，是不是在logic层方法里面直接创建model实例也可以？如：

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This is a service. It is responsible for one module. There won’t be too many models. If the business is complex, you can split the service model and there won’t be too many models. Of course, you don’t need to write it like this.

[LeeSeika]

Oppositely, I think the example u show might have a worse performance. Because there are always dao objects to be created and collected by GC every time the method is called.

[gzlboy]

Oppositely, I think the example u show might have a worse performance. Because there are always dao objects to be created and collected by GC every time the method is called.

Thanks for the reply! At first, I also felt that it was wrong to create a database connection object in the request method. Later, I followed up and found that connection pool technology was used, so I was confused. If there are many tables (50+), wouldn't it be bloated to write them all in ServiceContext? Does everyone write like this?

[wojiukankan]

相反，我认为你展示的示例性能可能会更差。因为每次调用该方法时总会有 dao 对象需要创建并由 GC 收集。

谢谢回复！一开始我也觉得在请求方法中创建数据库连接对象是不对的，后来跟进发现用到了连接池技术，于是就很疑惑，如果表很多（50+），全部写在ServiceContext中岂不臃肿？大家都是这么写的吗？

写到serviceContext里是把serviceContext当容器在用。

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On the contrary, I think the example you showed may perform even worse. Because every time this method is called, there will always be a dao object that needs to be created and collected by the GC.

Thank you for your reply! At first, I thought it was wrong to create a database connection object in the request method. Later, I found out that connection pooling technology was used, so I was confused. If there are many tables (50+), wouldn't it be bloated to write them all in the ServiceContext? Is this how everyone writes?

Writing into serviceContext uses serviceContext as a container.