Thymeleaf Spring Boot JPA無法從數據庫獲取數據，未檢測到錯誤

Question

我正在使用Spring Boot進行一個項目，並且試圖集成Thymeleaf從數據庫中獲取信息。 這是我第一次使用Thymeleaf。

這是我的實體類：

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;
    }

}

這是我的控制器：

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);
    //    }
    }

我創建一個HTML文件以在表中顯示數據：

    <!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>

我將Thymleaf依賴項添加到pom.xml

<?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>

我沒有錯誤，但是控制台中的白屏沒有錯誤：

在此處輸入圖片說明

Answer 1

您添加了名稱為“國家/地區”的modelAttribute，但是在Thymeleaf中，您嘗試通過將modelAttribute設置為以下方式來調用“國家/地區”：

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

編輯：

也改變你的百里香。

<tr th:each="Country : ${countries}">

檢查此列表以查看可以使用的名稱。 （如果它沒有自動滾動到該章節，則為5.2將值設置為特定屬性 。

Answer 2

只是一個主意，但我遇到了類似的問題，您確定要訪問數據庫，而不是在運行時使用實體創建的數據庫。

檢查countryRepository.findAll（）是否正在返回記錄。

Answer 3

似乎百里香不接受ForEach，我將其更改為每個，而他接受。

Thymeleaf Spring Boot JPA無法從數據庫獲取數據，未檢測到錯誤

問題描述

3 個解決方案

解決方案1
0 2017-11-03 13:12:31

解決方案2
0 2017-11-03 13:44:31

解決方案3
0 已采納 2017-11-03 14:05:57

Thymeleaf Spring Boot JPA無法從數據庫獲取數據，未檢測到錯誤

問題描述

3 個解決方案

解決方案1 0 2017-11-03 13:12:31

解決方案2 0 2017-11-03 13:44:31

解決方案3 0 已采納 2017-11-03 14:05:57

解決方案1
0 2017-11-03 13:12:31

解決方案2
0 2017-11-03 13:44:31

解決方案3
0 已采納 2017-11-03 14:05:57