rails验证::allow_nil和:inclusion都需要在同一时间 [英] rails validation: :allow_nil and :inclusion both needed at the same time

问题描述

通常应将字段种类"留为空白. 但如果不为空，则该值应包含在['a'，'b']

Usually the field 'kind' should be allowed blank. but if it is not blank, the value should included in ['a', 'b']

validates_inclusion_of :kind, :in => ['a', 'b'], :allow_nil => true

代码不起作用?

推荐答案

此语法将在允许nils的同时执行包含验证:

This syntax will perform inclusion validation while allowing nils:

validates :kind, :inclusion => { :in => ['a', 'b'] }, :allow_nil => true

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