我正在尝试使用以下命令为rails迁移添加索引:
rails generate migration add_user_id_to_pins user_id:integer:index
我收到此错误:
irb(main):014:0> rails generate migration add_user_id_to_pins user_id:integer:index
SyntaxError: (irb):14: syntax error, unexpected tLABEL
rails generate migration add_user_id_to_pins user_id:integer:index
^
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-4.1.4/lib/rails/commands/console.rb:90:in `start'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-4.1.4/lib/rails/commands/console.rb:9:in `start'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-4.1.4/lib/rails/commands/commands_tasks.rb:69:in `console'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-4.1.4/lib/rails/commands/commands_tasks.rb:40:in `run_command!'
from C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/railties-4.1.4/lib/rails/commands.rb:17:in `<top (required)>'
from bin/rails:4:in `require'
from bin/rails:4:in `<main>'
如果它有进一步帮助,这是我的模型:用户类:
class User < ActiveRecord::Base
# Include default devise modules. Others available are:
# :confirmable, :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable, :validatable
has_many :pins
end
针脚类:
class Pin < …看看这个.此登录表单中的复选框很难放错位置.这是我的views/devise/new.html.erb:
<div class="panel panel-default">
<div class="panel-heading">
<div class="panel-title">
<h1>Sign in</h1>
</div>
</div>
<div class="panel-body">
<%= form_for(resource, :as => resource_name, :url => session_path(resource_name)) do |f| %>
<div class="form-group">
<%= f.label :email %>
<%= f.email_field :email, class: "form-control", :autofocus => true %>
</div>
<div class="form-group">
<%= f.label :password %>
<%= f.password_field :password, class: "form-control" %>
</div>
<div class="form-group">
<div class="checkbox">
<%= f.check_box :remember_me %>
<%= f.label :remember_me %>
</div>
</div>
<div class="form-group">
<%= f.submit "Sign in", class: "btn …我搜索了关于我的问题的SO,但没有找到符合我情况的相关示例.
public class Game{
static enum Tile
{
static //Syntax error, insert "Identifier" to complete EnumConstantHeader
{
DIRT = new Tile("DIRT", 1); //Cannot instantiate the type Game.Tile
GRASS = new Tile("GRASS", 2);
ROCK = new Tile("ROCK", 3);
EXIT = new Tile("EXIT", 4);
PLAYER = new Tile("PLAYER", 5);
PLAYER_LEFT = new Tile("PLAYER_LEFT", 6);
PLAYER_RIGHT = new Tile("PLAYER_RIGHT", 7);
//For all above declared fields, I am getting this compile time errors :
/*
Multiple markers at this line
- Cannot instantiate the …我试图在Android上开始使用Parse推送通知,但我找不到任何方法来实现我自己的BroadcastReceiver,它会执行响应推送通知的操作.
在他们的"入门"中,他们给出了一个程序示例,其中接收器和intent服务包含在jar文件中(并且未在代码中实现,因此我可以尝试使用它).这里也提出了类似的问题,但它已经两年了,答案有11个问题.
还有一些其他的博客文章,例如在这里,但没有一个正常工作(该链接中的一个是两年).
所以请建议一步一步地实施同样的方法.
编辑:
我按照droidx的建议尝试了代码.但它不起作用.我正在发送我的AndroidManifest.xml(其余代码完全按照他的建议):
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.rahulserver.parsenotificationdemo" >
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.VIBRATE" />
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" />
<uses-permission android:name="android.permission.GET_ACCOUNTS" />
<uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
<!--
IMPORTANT: Change "com.parse.starter.permission.C2D_MESSAGE" in the lines below
to match your app's package name + ".permission.C2D_MESSAGE".
-->
<permission android:protectionLevel="signature"
android:name="com.rahulserver.parsenotificationdemo.permission.C2D_MESSAGE" />
<uses-permission android:name="com.rahulserver.parsenotificationdemo.permission.C2D_MESSAGE" />
<application
android:name=".ParseNotification"
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category …如果我们在这里读取add函数的ArrayList文档,显然在无效索引处添加元素会抛出IndexOutOfBoundsException.但为什么以下代码不会抛出任何异常？
public static void main(String args[]){
List cities = new ArrayList();
cities.add("Atlanta");
cities.add("Boston");
try {
for (int i = 10000000; i < cities.size(); i++){
try {
cities.add(i, "+");
} catch (Exception e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
System.out.println(cities.size());
}
} catch (Exception e) {
e.printStackTrace(); //To change body of catch statement use File | Settings | File Templates.
}
System.out.println(cities);
}
输出:
[Atlanta, Boston]
Process finished with …