User.eachdo|user|#在Rails2中通常这么使用:User.all.each do |user| NewsLetter.weekly_deliver(user) end 在调用each方法的时候,整个users表的数据都会被载入内存。如果用户总数是一个非常大的数字,将会因为内存被占用过多而导致性能低下。 Model.find_each 为了改善遍历大表的性能,ActiveRecord提供了一个find_e...
User.eachdo|user|#在Rails2中通常这么使用:User.all.each do |user| NewsLetter.weekly_deliver(user) end 在调用each方法的时候,整个users表的数据都会被载入内存。如果用户总数是一个非常大的数字,将会因为内存被占用过多而导致性能低下。 Model.find_each 为了改善遍历大表的性能,ActiveRecord提供了一个find_e...
I tried running the code against individual records that were not being processed and they are processed as expected. But as soon as I put it into the find_each loop it does not work. I also tried using IneventoryRecord.all.each but that seems to have the same problem. I also tried ...
each do |client| %> <%= client.id %> <%= client.business_name %> <%= client.industries.first.name %> <% end %> # app/controllers/clients_controller.rb def index @clients = Client.all end 如果有50个 Clients, 则会有51条数据库查询: Processing by ClientsController#index as HTML...
现在现在查出来的数据对象比较少,可以直接用拿到前台页面直接each使用。但是,如果查出的数据对象太多了,一次查询出来可能会很慢,放到前台有可能还会撑爆页面,会产生浏览障碍,这个时候可能需要进行分页显示。那么拿我们平时很常用的gem 'kaminari'来做分页吧。
record = YourModel.find_by(column1: value1, column2: value2) 这将返回满足条件的第一条记录,如果没有找到匹配的记录,则返回nil。 如果你需要执行更复杂的查询,可以使用Active Record的where方法的高级用法,例如使用SQL语句的条件: 代码语言:txt 复制 records = YourModel.where("column1 = ? AND column2...
在Rails中,可以使用Active Record提供的查询方法来查询带参数和不带参数的记录。 查询不带参数的记录:可以使用all方法来查询表中的所有记录,例如: 查询不带参数的记录:可以使用all方法来查询表中的所有记录,例如: 这将返回一个包含所有记录的数组。 查询带参数的记录:可以使用where方法来查询符合特定条件的记...
? Company.all : Company.find(args) companies.each do |company| configuration[:database] = "database_name_#{company[:id]}_#{RAILS_ENV}" ActiveRecord::Base.establish_connection configuration yield self end configuration[:database] = former_database ActiveRecord::Base.establish_connection ...
In particular, these two commands cancel each other out:$ rails generate controller FooBars baz quux $ rails destroy controller FooBars baz quux Similarly, in Chapter6 we'll generate a model as follows:$ rails generate model Foo bar:string baz:integer ...
MVC divides your application into three layers: Model, View, and Controller, each with a specific responsibility. Model layer The Model layer represents the domain model (such as Account, Product, Person, Post, etc.) and encapsulates the business logic specific to your application. In Rails, ...