java - Thyemleaf 嵌套迭代触发 org.thymeleaf.exceptions.TemplateInputException

Question

我正在尝试遍历对象列表并生成 div class="card-deck"每4对象和嵌套 div class="card"对于每个对象。

这是在 上生成异常的代码第 234 行

更新:注:第 234 行 在 html 中提到并拥有 <!-- Error-Line 234 -->由于缺少 )在 ${#numbers.sequence(0,3}

    <div class="card-deck" th:each="qr: ${objects}" th:if="${qr.tableid}%4==0"> <!-- Iterate every 4 objects -->

    <!--syntax error missed clossing ) at ${#numbers.sequence(0,3) triggered the exception here -->
    <div class="card" th:each="i : ${#numbers.sequence(0,3)} ">   <!-- Error-Line 234 -->


        <!-- Some More Code -->
        <img th:src="${qr.qrcodestaticpath}" class="card-img-top" alt="...">
        <div class="card-body">
            <h5 class="card-title" align="center" th:text="'Table '+${qr.tableid}"></h5>
            <p class="card-text" align="center" th:text="'Random Generated QR Code'"></p>
            <h6 align="center" th:text=" ${qr.qrcodestring}"></h6>

        </div>
    </div>
  </div>

org.thymeleaf.exceptions.TemplateInputException: An error happened during template parsing (template: "class path resource [templates/qrcodes.html]" - line 234, col 10)

我已经讨论过这些话题

How to do if-else in Thymeleaf?

Thymeleaf Loop Until a Number

nested (double) loop with thymeleaf

Thymeleaf - How to loop a list by index

并浏览了本文档

Iteration in Thymeleaf | Baeldung

并且仍然无法找到正确的方法，而不触发 exception
更新:异常已修复，我正在尝试实现的逻辑没有预期的结果:

以上片段的结果:



想象一下有 8 个表， table1, table2 ... table8 ，我试图生成一个 <div class="card-deck" ...每 4 或 5 table 。由于 <div class="card" th:each="i : ${#numbers.sequence(0,3)} ">我得到了 4 张相同的 table 。

qr.tableid是表号，1 到 x

出于演示目的，请查看此 java片段

int numOfObjects=11;
    for(int i=0 ;i<numOfObjects;i++)
    {
        if(i%4==0)
        {
           System.out.println();
           System.out.print("Deck:");
        }
          System.out.print("Card"+(i+1)+" ");    
     }

输出:



这是我的 Controller

@GetMapping("/qrcodes")
      public String greetingForm(Model model) {

        List<QrObject> qr =qrRepo.findAll();
        int numOfobj= qr.size();
        int decks;

        if(numOfobj % 4==0)
            decks = numOfobj / 4 ;
        else
            decks = (numOfobj / 4) +1 ;

        int posa_periseuoun = numOfobj % 4 ;
        model.addAttribute("objects", qr);
        model.addAttribute("decks",decks);
        model.addAttribute("cards",posa_periseuoun);
        model.addAttribute("size", numOfobj);
        return "qrcodes";
      }

Answer 1

这是一种我认为代表您正在尝试做的方法。

最终结果

跳转到最终结果，这将在浏览器中显示以下文本:

Deck: Card1 Card2 Card3 Card4
Deck: Card5 Card6 Card7 Card8
Deck: Card9 Card10 Card11 

更有用的是，HTML 如下所示:

<div class="card-deck">
    <span>Deck: </span>
    <span class="card">Card1 </span>
    <span class="card">Card2 </span>
    <span class="card">Card3 </span>
    <span class="card">Card4 </span>
</div>
<div class="card-deck">
    <span>Deck: </span>
    <span class="card">Card5 </span>
    <span class="card">Card6 </span>
    <span class="card">Card7 </span>
    <span class="card">Card8 </span>
</div>
<div class="card-deck">
    <span>Deck: </span>
    <span class="card">Card9 </span>
    <span class="card">Card10 </span>
    <span class="card">Card11 </span>
 </div>

Java 对象

甲板:

public class Deck {

    private final String deckName;
    private final List<Card> cards = new ArrayList();

    public Deck(String deckName) {
        this.deckName = deckName;
    }

    public List<Card> getCards() {
        return cards;
    }

    public String getDeckName() {
        return deckName;
    }

}

卡片:

public class Card {

    private final String cardName;

    public Card(String cardName) {
        this.cardName = cardName;
    }

    public String getCardName() {
        return cardName;
    }

}

组装甲板:

Map<String, Object> model = new HashMap();

// this is equivalent to your findAll()...
List<Card> allCards = new ArrayList();
for (int i = 1; i<= 11; i++) {
    allCards.add(new Card("Card" + i));
}

int maxCardsPerDeck = 4;        
List<Deck> decks = new ArrayList();

Deck deck;
List<Card> deckCards = new ArrayList();
int cardCount = 0;
for (Card card : allCards) {
    cardCount++;
    deckCards.add(card);
    if (cardCount % maxCardsPerDeck == 0 ||
            cardCount == allCards.size()) {
        deck = new Deck("Deck");
        deck.getCards().addAll(deckCards);
        decks.add(deck);
        deckCards.clear();
    }
}

model.put("decks", decks);

上面的代码相当粗糙 - 它可能会被改进。但重点是:它组合了一组牌组，每副牌组包含的牌数不超过允许的最大数量(在本例中为 4)。

thymeleaf

<div class="card-deck"
     th:each="deck: ${decks}">
    <span th:text="${deck.deckName + ': '}">
    </span>
    <span class="card"
          th:each="card: ${deck.cards}"
          th:text="${card.cardName + ' '}">
    </span>
</div>

我用过 <span> s 在这里，只是为了让事情保持一致。你可以使用任何你需要的东西，并提供你需要的 CSS 样式。