小编Ric*_*men的帖子

即使我的应用程序不允许用户键入某个位置,我也希望在数据库中强制执行城市的唯一性.由于我的Rails应用程序将在city列上搜索,我想在city列上添加一个索引,但是想知道是否重要的​​是添加唯一:true也在索引上.这是重复吗？如果这没有意义,如果你能解释原因,我将非常感激.

class CreateLocations < ActiveRecord::Migration
  def change
    create_table :locations do |t|
      t.string :city, unique: true
      t.string :state

      t.timestamps
    end

    add_index :locations, :city, unique: true
  end
end

我通常在DreamInCode.net上发帖,但该网站现在似乎已经关闭了.我是De Anza的第一个学期CS学生.我真的不明白lineCount = 1; 在else语句中.我知道当我删除声明时它会做什么,但我不明白.如果我可以让某人向我解释这可能是因为这本书恰好跳过了,我会非常感激.

#include <stdio.h>
int main (void) {

    int num;
    int lineCount;

    printf ("\nEnter a starting number to decend between 1 and 100: ");
    scanf  ("%d", &num);

    if (num > 100)
        num = 100;

    lineCount = 0;

    while (num >= 0)
    {
        if (lineCount < 10)
            lineCount++;
        else
        {
            printf ("\n");
            lineCount = 1; // this line here is what I don't understand
        }
        printf ("%4d", num--);
    }
    return 0;
}

我已经有一段时间没有在 Rails 中工作了，并且在正确设置路线方面遇到了一些问题。任何帮助将不胜感激。

URL: http://localhost:3000/admin/products/new

Error: undefined method `products_path' for #<#<Class:0x007f9f569d0150>:0x007f9f578ccb18>

耙路线

admin_products     GET    /admin/products(.:format)          admin/products#index
                   POST   /admin/products(.:format)          admin/products#create
new_admin_product  GET    /admin/products/new(.:format)      admin/products#new
edit_admin_product GET    /admin/products/:id/edit(.:format) admin/products#edit
admin_product GET         /admin/products/:id(.:format)      admin/products#show
                   PUT    /admin/products/:id(.:format)      admin/products#update
                   DELETE /admin/products/:id(.:format)      admin/products#destroy

路线.rb

Aneprize::Application.routes.draw do
  devise_for :admins, :users

  namespace :admin do
    match '/', to: 'dashboard#index', as: '/'

    authenticated :admin do
      root to: 'dashboard#index', as: :root

      resources :products do
        resource  :contest
        resources :bids
        resources :photos
        resources :tags
      end
    end
  end

  root to: 'contests#index'
end

产品.rb

class …