Question

我正在尝试在简单的vaadin UI中打印数据库中的值。我正在完成本教程的所有内容：https://vaadin.com/blog/-/blogs/building-a-web-ui-for-mysql-databases-in-plain-java-

我稍微改了一下，我无法弄清楚为什么我不能自己设置列。如果我用setColumns和bindInstanceFields注释行，一切都有效，但顺序相反......在另一种情况下，我得到标题中提到的错误。

以下是代码：

日级：

package com.ti.project.vaadin.vaadinprojectti;

public class Day {
    private String hourToReserve;
    private String reservedOn;

    public Day(String hourToReserve, String reservedOn) {
        this.hourToReserve = hourToReserve;
        this.reservedOn = reservedOn;
    }

    public String getHourToReserve() {
        return hourToReserve;
    }

    public void setHourToReserve(String hourToReserve) {
        this.hourToReserve = hourToReserve;
    }

    public String getReservedOn() {
        return reservedOn;
    }

    public void setReservedOn(String reservedOn) {
        this.reservedOn = reservedOn;
    }
}

DayService类：

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Component;

import java.util.List;

@Component
public class DayService {

    @Autowired
    private JdbcTemplate jdbcTemplate;

    public List<Day> findAll(String dayName) {
        return jdbcTemplate.query(
                "SELECT hourtoreserve, reservedon FROM " + dayName,
                (rs, rowNum) -> new Day(
                        rs.getString("hourtoreserve"),
                        rs.getString("reservedon")));
    }

    public void update(Day day, String dayName){
        jdbcTemplate.update(
                "UPDATE " + dayName + " SET reservedon=?",
                day.getReservedOn());
    }
}

以及发生错误的Vaadin UI代码：

package com.ti.project.vaadin.vaadinprojectti;

import com.vaadin.data.Binder;
import com.vaadin.server.VaadinRequest;
import com.vaadin.spring.annotation.SpringUI;
import com.vaadin.ui.*;
import org.springframework.beans.factory.annotation.Autowired;


@SpringUI
public class VaadinUI extends UI {

@Autowired
private DayService service;

private Day day;
private Binder<Day> binder = new Binder<>(Day.class);

private Grid<Day> grid = new Grid(Day.class);

@Override
protected void init(VaadinRequest request) {

    updateGrid();

    grid.setColumns("hourtoreserve", "reservedon"); // if this is commented 
    binder.bindInstanceFields(this);           // it works but columns are in wrong order
    VerticalLayout layout = new VerticalLayout(grid);
    setContent(layout);
}

private void updateGrid() {
    List<Day> days = service.findAll("monday");
    grid.setItems(days);
}

Answer 1

我解决了我的问题。原来你需要在grid.setColumns（）方法中输入你绑定的类的确切变量名！所以在我的情况下，它应该是：

而不是：

 grid.setColumns("hourtoreserve", "reservedon")

它应该是：

 grid.setColumns("hourToReserve", "reservedOn")

java.lang.IllegalArgumentException：无法解析bean com.ti.project.vaadin.vaadinprojectti.Day的属性集中的属性名称hourtoreserve

1 个答案: