Thymeleaf 错误 spring boot jpa答案

【问题标题】：Thymeleaf error spring boot jpaThymeleaf 错误 spring boot jpa
【发布时间】：2018-04-16 03:18:34
【问题描述】：

大家早安，

我在一个使用spring boot的项目中工作，我正在尝试集成thymleaf以从数据库中获取信息，这是我第一次使用thymleaf，

这里是我的实体类：

package com.org.model;

import java.io.Serializable;
import javax.persistence.*;

import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonManagedReference;

import java.math.BigDecimal;
import java.util.List;


/**
 * The persistent class for the countries database table.
 * 
 */
@Entity
@Table(name="countries")
//@NamedQuery(name="Country.findAll", query="SELECT c FROM Country c")

public class Country implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @Column(name="COUNTRY_ID")
    private String countryId;

    @Column(name="COUNTRY_NAME")
    private String countryName;

    //bi-directional many-to-one association to Region

    @ManyToOne
    @JoinColumn(name="REGION_ID")
    private Region region;

    //bi-directional many-to-one association to Location
    @JsonIgnore
    @OneToMany(mappedBy="country")
    private List<Location> locations;

    public Country() {
    }

    public String getCountryId() {
        return this.countryId;
    }

    public void setCountryId(String countryId) {
        this.countryId = countryId;
    }

    public String getCountryName() {
        return this.countryName;
    }

    public void setCountryName(String countryName) {
        this.countryName = countryName;
    }

    public Region getRegion() {
        return this.region;
    }

    public void setRegion(Region region) {
        this.region = region;
    }

    public List<Location> getLocations() {
        return this.locations;
    }

    public void setLocations(List<Location> locations) {
        this.locations = locations;
    }

    public Location addLocation(Location location) {
        getLocations().add(location);
        location.setCountry(this);

        return location;
    }

    public Location removeLocation(Location location) {
        getLocations().remove(location);
        location.setCountry(null);

        return location;
    }

}

这是我的控制器：

package com.org.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;

import com.org.model.Country;
import com.org.repository.CountryRepository;

    @Controller    // This means that this class is a Controller
@RequestMapping(path="/api", produces=MediaType.APPLICATION_JSON_VALUE) // This means that this class is a Controller

public class CountryController {
        @Autowired // This means to get the bean called userRepository
        // Which is auto-generated by Spring, we will use it to handle the data
    private CountryRepository countryRepository;



        @RequestMapping(value="/country", method= RequestMethod.GET)
        public String list(Model model){
            model.addAttribute("Country", countryRepository.findAll());


            // This returns a JSON or XML with the users
            return "countries";
        }


    //  @RequestMapping(path="/country/{countryId}")
    //    public @ResponseBody Country getCountry(@PathVariable String countryId) {
    //        return countryRepository.findOne(countryId);
    //    }
    }

我创建了一个 html 文件来绘制信息：

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org" xmlns:sec="http://www.thymeleaf.org/extras/spring-security">
<head lang="en">

</head>
<body>
<div class="container">
    <!--/*/ <th:block th:include="fragments/header :: header"></th:block> /*/-->

<div th:if="${not #lists.isEmpty(countries)}">

        <table class="table table-striped">
            <tr>
                <th>Country Id</th>
                <th>Country Name</th>
                <th>Region Id</th>
                <th>Location</th>

            </tr>
            <tr th:ForEach="Country : ${countries}">
                <td th:text="${Country.countryId}">id country</td>
                <td th:text="${Country.countryName}">Country Name</td>
                <td th:text="${Country.region}">Region Id</td>
                <td th:text="${Country.locations}">Location</td>

            </tr>
        </table>

    </div>

</div>

</body>
</html>

我在 pom.xml 中添加了 thymleaf 依赖项

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>xxxx.org</groupId>
    <artifactId>project</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>webService</name>
    <description>first project for university</description>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.7.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-rest</artifactId>
        </dependency>
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger2</artifactId>
    <version>2.6.1</version>
    <scope>compile</scope>
</dependency>
<dependency>
    <groupId>io.springfox</groupId>
    <artifactId>springfox-swagger-ui</artifactId>
    <version>2.6.1</version>
    <scope>compile</scope>
</dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
  <groupId>org.modelmapper</groupId>
  <artifactId>modelmapper</artifactId>
  <version>1.1.0</version>
</dependency>
        <dependency>
            <groupId>org.thymeleaf</groupId>
            <artifactId>thymeleaf-spring4</artifactId>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

我没有错误，但控制台中的白屏没有错误：

[本地主机截图]https://i.stack.imgur.com/6xx1l.png

【问题讨论】：

您正在使用countries 两次...${countries} 是您的列表，因此${countries.countryId} 引用了该列表。你可能想要th:each="country : ${countries}" 这样的东西，然后在里面使用${country.} 而不是${countries}。
我不知道为什么，但现在我得到了一个白色的屏幕，eclipse 中的控制台没有错误！
对于控制台中的错误，您需要为您的国家/地区实体属性提供公共 getter。
它们是公开的，我将编辑我的问题以放置实体类

标签： java html spring-boot thymeleaf

【解决方案1】：

<tr th:ForEach="countries : ${countries}">

在上述行中，您使用的是引用列表和列表中每个项目且无法区分的国家/地区。所以你可以试试下面的代码sn-p

<tr th:ForEach="country : ${countries}">

【讨论】：

是的，我已经这样做了，现在我得到了一个白色的屏幕，eclipse 中的控制台没有错误！

【解决方案2】：

您在模型中定义属性“国家/地区”并使用国家/地区列表填充它：

model.addAttribute("Country", countryRepository.findAll());

但是你正在寻找“国家”：

<div th:if="${not #lists.isEmpty(countries)}">

所以你可以这样做：

model.addAttribute("countries", countryRepository.findAll());

或者这个：

<div th:if="${not #lists.isEmpty(Country)}">
...
<tr th:ForEach="element : ${Country}">

【讨论】：