为什么使用 Flex 4 Beta 2 多次调用验证器

Question

我在 Flex 4 beta 2 中创建了一个自定义验证器，如下所示：

// ActionScript file
package com.lal.validators
{
    import mx.controls.Alert;
    import mx.validators.ValidationResult;
    import mx.validators.Validator;


    public class BirthDateValidator extends Validator {

        // Define Array for the return value of doValidation().
        private var results:Array;
        private var MIN_DATE_LENGTH:int = 8;
        private var MAX_DATE_LENGTH:int = 10;
        private var LENGTH_OF_DATE_ARRAY:int = 3;

        // Constructor.
        public function BirthDateValidator() {
            // Call base class constructor.
            super();
        }

        // Define the doValidation() method.
        override protected function doValidation(value:Object):Array {

            // Convert value to a Number.
            var inputValue:Number = Number(value);

            // Format of Date of Birth
            const DDMMYYYY : String = "DDMMYYYY";

            // Clear results Array.
            results = [];

            // Call base class doValidation().
            results = super.doValidation(value);        
            // Return if there are errors.
            if (results.length > 0)
                return results;

            // Case where user didn't input complete date
            if (value.length < MIN_DATE_LENGTH || value.length > MAX_DATE_LENGTH) {
                trace ("IsDateDDMMYYYYValid wrong date length");
                Alert.show("error with length", "hey");
                results.push(new ValidationResult(true, null, "NaN", 
                    "Please enter a date in the Format DD-MM-YYYY"));
                return results;
            }           

            var arrayOfDate:Array = value.toString().split("-")

            if(arrayOfDate.length != LENGTH_OF_DATE_ARRAY){
                trace ("When Splitting the array into three parts I didn't get 3 as it should be");
                Alert.show("error with length", "hey");
                results.push(new ValidationResult(true, null, "NaN", 
                    "Please enter a date in the Format DD-MM-YYYY"));
                return results;
            }

            // Alert.show("day: " + arrayOfDate[0] + " month: " + arrayOfDate[1] + " year: " + arrayOfDate[2]," The Parsed Date.");

            var currentDate:Date = new Date();
            var date:Date = new Date(parseInt(arrayOfDate[2]), parseInt(arrayOfDate[1])-1, parseInt(arrayOfDate[0]));

            if(currentDate < date){
                trace ("Date of Birth is greater than now!");
                Alert.show("error with date position current:" + currentDate + " the date: " + date, "hey");
                results.push(new ValidationResult(true, null, "NaN", 
                    "Please enter a date that is before today's date"));
                return results; 
            }

            return results;
        }
    }
}

那我这样称呼它：

    <vld:BirthDateValidator id="dobValidator" source="{dateOfBirth}" 
                            property="text"
                            trigger="{dateOfBirth}"
                            triggerEvent="valueCommit"
                            />

它可以工作，但如果你注意到我有一个用于测试的警报窗口，它会显示 4 次，这意味着验证器被调用了 4 次。这正常吗？还是我做错了什么？

谢谢，

谭

Answer 1

绑定变量 dateOfBirth 可以在其父对象的实例化和配置过程中多次评估。

每个评估都会发生 valueCommit 事件。