如果一个表单字段具有多个验证器，那么如何让它们逐个而不是全部对它们进行验证? [英] If a form field has multi validators, how to let play verify them one by one, not all?

问题描述

我有一个登录表单，有一个name输入有很多验证器:

I have a login form in view, there is a name input has many validators:

object Users extends Controller {

    val loginForm = Form(tuple(
        "name" -> ( 
            nonEmptyText // (1)
            verifying ("Its length should >= 4", name=>{ println("#222");name.length>=4 }) // (2)
            verifying ("It should have numbers and letters", name=>{println("#333"); ...}) // (3)
        )
}

然后我什么也没输入，按提交，发现控制台打印了

Then I don't input anything, press submit, and I found the console prints:

#222
#333

这意味着所有验证者都已执行，并且它们之间具有关系:

That means all validators performed, and they have relationship:

(1) & (2) & (3)

但是我希望他们:

(1) && (2) && (3)

这意味着，如果名称为空，则后面的两个验证器将被忽略.

That means, if the name is empty, the later two validators will be ignored.

在play2中可以吗?

Is it possible in play2?

推荐答案

默认行为是对字段定义所有约束. 但是，您可以定义自己的验证约束，以在第一次失败时停止应用约束:

The default behavior is to apply all the constraints defined on a field. However, you can define your own validation constraint that stops applying constraints on the first fail:

def stopOnFirstFail[T](constraints: Constraint[T]*) = Constraint { field: T =>
  constraints.toList dropWhile (_(field) == Valid) match {
    case Nil => Valid
    case constraint :: _ => constraint(field)
  }
}

它的用法如下:

val loginForm = Form(
  "name" -> (text verifying stopOnFirstFail(
    nonEmpty,
    minLength(4)
  ))
)

scala> loginForm.bind(Map("name"->"")).errors
res2: Seq[play.api.data.FormError] = List(FormError(name,error.required,WrappedArray()))

scala> loginForm.bind(Map("name"->"foo")).errors
res3: Seq[play.api.data.FormError] = List(FormError(name,error.minLength,WrappedArray(4)))

scala> loginForm.bind(Map("name"->"foobar")).errors
res4: Seq[play.api.data.FormError] = List()

(请注意，我在stopOnFirstFail的实现中应用了失败约束的两倍，因此该约束没有副作用)

(Note that my implementation of stopOnFirstFail applies two times the failing constraint, so this one should not have side effects)

这篇关于如果一个表单字段具有多个验证器，那么如何让它们逐个而不是全部对它们进行验证?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！