Question

我想在Rails 5中的一个表中添加一个新列。我最近使用以下方式重命名了一个列：

import java.awt.GridLayout;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;
import java.io.InputStream;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JPanel;
import javax.swing.Icon;



public class GameBoard extends JPanel implements ActionListener {

private JButton B1, B2, B3, B4, B5, B6, B7, B8, B9; 
private GameArray GArray; 
private boolean Player = false;
private int PlayerMark = 1;

GameBoard() {

    setLayout(new GridLayout(3, 3));

    B1 = new JButton();
    ...
    B9 = new JButton();

    SetGame();

    add(B1);
    ...
    add(B9);

    B1.addActionListener(this);
    ...
    B9.addActionListener(this);

}

public void SetGame() {

    GArray = new GameArray(this);

    DefaultText();
    DisableAll(true);

    Player = false; 
    PlayerMark = 1;
}

public void Reset() {

    SetGame(); 

}

public void actionPerformed(ActionEvent E) {

    ...

}

//Other methods

public void SetText(JButton Btn, boolean Play) {

    if (Play == true) {
        Btn.setText("O");

    } else if (Play == false) {

        Btn.setIcon(new ImageIcon(GameBoard.class.getResource("red.png")));

    }
  }
}

然后在rails g migration ChangeJobsTable：

20160802104312_change_jobs_table.rb

然后

class ChangeJobsTable < ActiveRecord::Migration[5.0]
  def change
    rename_column :jobs, :skills, :skills1
  end
end

它工作正常，但现在如果我还要添加新列rails db:migrate，我是否需要像这样做？

skills2

Answer 1

您忘记添加datatype，以下是更新后的迁移。

class ChangeJobsTable < ActiveRecord::Migration[5.0]
  def change
    add_column :jobs, :skills2, :string
  end
end

Answer 2

你确实忘记了datatype。您也可以在将来通过控制台执行此操作：

rails g migration AddSkills2ToJobs skills2:string

Answer 3

这对我有用，您可以在模式中进行验证

rails g migration add_skills2_to_ChangeJobsTable skills2:string

rake db:migrate

如何在Rails 5中的现有表中添加新列？

3 个答案: