Question

我有以下豆子：

class User {
    private List<Address> addresses;

    // ... getter and setter for addresses follows
}

class Address {
    private String street, city;

    // ... getters and setters follows 
}

这是控制器

@RequestMapping(value = { "/doSomething" })
public String doSomething(@ModelAttribute User user, BindingResult result, Model model) {
    // ...
}

表格可能类似

<form>
    <input type="text" name="addresses[].street" />
    <input type="text" name="addresses[].city" />
    ...
</form>

但是我收到以下错误

Request processing failed; nested exception is org.springframework.beans.InvalidPropertyException: Invalid property 'addresses[]' of bean class [User]: Invalid index in property path 'addresses[]'; nested exception is java.lang.NumberFormatException: For input string: ""
java.lang.NumberFormatException: For input string: ""
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65) ~[na:1.8.0_31]
at java.lang.Integer.parseInt(Integer.java:592) ~[na:1.8.0_31]
at java.lang.Integer.parseInt(Integer.java:615) ~[na:1.8.0_31]
at org.springframework.beans.BeanWrapperImpl.setPropertyValue(BeanWrapperImpl.java:989) ~[spring-beans-4.1.2.RELEASE.jar:4.1.2.RELEASE]

如何命名表单中的字段以便Spring能够进行绑定？

Answer 1

我认为错误是因为它无法将[“”]转换为[number]，因此无法找到它应该访问的数组中的哪个元素。

对于集合，您可以使用ngRepeat循环或使用显式索引。在大多数情况下，你会想要循环，所以这是一个例子：

<form ng-repeat="address in user.addresses">
    <input type="text" ng-model="address.street" />
    <input type="text" ng-model="address.city" />
    ...
</form>

请注意，如果您使用angular提交表单，则此方法有效（因此，您可以提交Angular正在修改的范围对象，而不是允许标准HTML提交。

Answer 2

我明白了。问题是该属性缺少索引。 Spring可以绑定多个属性（集合，列表，数组）来请求参数，但名称必须包含索引。

所以表格必须是

   import java.util.Random;
import java.util.Scanner;

public class Dice {

    public static void main(String[] args) {

        int guess = 0;
        int tries = 3;
        Scanner input = new Scanner(System.in);
        Random ran = new Random();
        int diceNumber = ran.nextInt(6) + 1;
        System.out.println(diceNumber);

        System.out.println("Insert a number between 1 and 6 : you have "
                + tries + " tries.");
        guess = input.nextInt();

        loop: while ((tries >= 1)) {
            --tries;
            if ((guess >= 7 || guess <= 0) && (tries >= 1)) {

                System.out.println("Number out of range, try again; you have "
                        + tries + " more tries.");
                guess = input.nextInt();
            } else {

                if (guess == diceNumber) {
                    System.out.println("You Win!!");
                    break loop;
                } else if (tries >= 1) {
                    System.out.println("Incorrect Number, you have " + tries
                            + " more tries.");
                    guess = input.nextInt();

                }
            }
        }

        if (tries == 0 && guess != diceNumber) {
            System.out.println("You Lose!!");
        }

    }
}

而不是<form> <input type="text" name="addresses[0].street" /> <input type="text" name="addresses[0].city" /> <input type="text" name="addresses[1].street" /> <input type="text" name="addresses[1].city" /> ... </form>，0 ...您可以在Thymeleaf（服务器端）使用1或在Angular（客户端）使用${iterationStatus.index}。

Spring绑定和表单字段命名

2 个答案: