django 对于数据已存在数据的表增加非空字段如何处理? - V2EX
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rationa1cuzz

django 对于数据已存在数据的表增加非空字段如何处理?

  •  
  •   rationa1cuzz Jan 13, 2021 2340 views
    This topic created in 1946 days ago, the information mentioned may be changed or developed.
    对于已经存在数据的表增加非空字段,makemigrations 会报错 You are trying to add a non-nullable field 'xx' to XXX without a default,有什么办法可以解决吗?还是说必须要给个默认值
    5 replies    2021-01-14 11:51:28 +08:00
    wuwukai007
        1
    wuwukai007  
       Jan 13, 2021
    null=True,blank=True
    xpresslink
        2
    xpresslink  
       Jan 13, 2021
    表增加非空字段必须要加 default:默认值,这可以是值或可调用对象。如果可调用,则每次创建新对象时都会调用它。
    enomine
        3
    enomine  
       Jan 13, 2021
    报错提示已经很明显了
    从 MySQL 层面来讲,非空表加一列非空字段,如果没有设置默认值,那已经存在的那些数据新加这个字段应该填充什么数据呢?
    IurNusRay
        4
    IurNusRay  
       Jan 14, 2021
    要么设置 null=True,要么手动设置一个默认值,比如 0 或者""
    msy45
        5
    msy45  
       Jan 14, 2021
    如果不需要默认值,migrate 完再把默认值取消再 migrate 一次
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