java - hibernate 默认值

Question

hibernate 有没有办法为每个字段定义默认值，并且为了数据库大小写 null 而不是这些默认值？

例如。假设 String 的默认值为“”。我希望 Hibernate 能够:

1. 为数据库中具有 NULL 的每个字段返回 ""。
2. 当我尝试写入 ""时，将 NULL 写入数据库

我当然可以写几千个Getters和Setters，但是能自动完成吗？

Answer 1

If you want a real database default value, use columnDefinition - @Column(name = “myColumn”, nullable = false, columnDefinition = “int default 100"). Notice that the string in columnDefinition is database dependent. Also if you choose this option, you have to use dynamic-insert, so Hibernate doesn't include columns with null values on insert. Otherwise talking about default is irrelevant.

But if you don't want database default value, but simply a default value in your Java code, just initialize your variable like that - private Integer myColumn = 100;

来源:

How to set default value in Hibernate

当然，而不是使用:

columnDefinition = “int default 100"

尝试这样的事情:

columnDefinition = “TEXT default `default_text`"

我不确定这在句法上是否正确，但请检查一下:

Text Field using Hibernate Annotation

Set default values using hibernate annotations in MYSQL