datamapper | 易学教程

How to fix a “value too long for type character varying(255)” error

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问题 I'm trying to save a file so that I can upload it to stripe using CarrierWave, but I'm getting the error: ERROR: value too long for type character varying(255) and don't understand why as I followed the CarrierWave usage guide on GitHub. This is my application: class SplitterStripeServer < Sinatra::Base CarrierWave.configure do |config| config.root = File.dirname(__FILE__) + "/public" end post "/" do img = Image.new img.file = params[:file] #carrierwave will upload the file automatically img

小书MybatisPlus第5篇-Active Record模式精讲

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本文为一个系列中的第五节，前四节访问如下地址：小书MybatisPlus第1篇-整合SpringBoot快速开始增删改查小书MybatisPlus第2篇-条件构造器的应用及总结小书MybatisPlus第3篇-自定义SQL 小书MybatisPlus第4篇-表格分页与下拉分页查询 Active Record 适合非常简单的领域需求，尤其在领域模型和数据库模型十分相似的情况下。如果遇到更加复杂的领域模型结构（例如用到继承、策略的领域模型），往往需要使用分离数据源的领域模型，结合 Data Mapper （数据映射器）使用。具体到使用层面，我们之前章节讲过使用Data Mapper 做数据的持久层操作。 User user = new User(); user.setName("字母哥"); user.setAge(18); userMapper.insert(user); //Mybatis Mapper模式现在我们使用ActiveRecord模式，用法如下，注意二者的区别 User user = new User(); user.setName("zimug"); user.setAge(18); user.insert(); //ActiveRecord模式一、使ActiveRecord模式生效首先：需要让数据库表对应的数据持久层实体类。集成自Model<User>

Postgres error with Sinatra/Haml/DataMapper on Heroku

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问题 I'm trying to move a simple Sinatra app over to Heroku. Migration of the Ruby app code and existing MySQL database using Taps went smoothly, but I'm getting the following Postgres error: PostgresError - ERROR: operator does not exist: text = integer LINE 1: ...d_at", "post_id" FROM "comments" WHERE ("post_id" IN (4, 17,... ^ HINT: No operator matches the given name and argument type(s). You might need to add explicit type casts. It's evident that the problem is related to a type mismatch in

How to add property-level Attribute to map ColumnAttribute at runtime?

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问题 From this question we have implemented the ColumnAttribute association with the corresponding property, but when Linq to SQL tries to map this property to a Column it doesn't work. Our property and mapping code(from the other question): public System.Xml.Linq.XElement Name { get { return this.name; } set { this.OnNameChanging(value); this.SendPropertyChanging(); this.name = value; this.SendPropertyChanged("Name"); this.OnNameChanged(); } } System.Data.Linq.Mapping.ColumnAttribute

PHP MVC: Multiple databases, multiple data mappers?

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问题 I am working on my HMVC project. Right now I am using data mappers in order to move data between the models (domain objects) and a MySQL database. Each mapper receives a MySQL adapter as dependency. The injected adapter receives a PDO instance (a database connection) as dependency and runs sql queries on the database. I also use a dependency injection container (Auryn). I'd like to be able to simultaneously retrieve data from storages of different types (MySQL database, PostgreSQL database,

PHP MVC: Multiple databases, multiple data mappers?

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How to fetch only specified fields of model with DataMapper?

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问题 I cant find the way to fetch only necessary fields of model in certain context. Let`s say i have a huge model which has about 30 fields (properties). But for a search purpose i need only couple of them. Example: class Foo include DataMapper::Resource property :id, Serial property :title, String, :length => 256 property :description, Text property :url, String, :length => 4096 property :city, String, :length => 64 property :country, String, :length => 64 property :state, String, :length => 64

How to build nested responses in an Apigility driven application with a ZfcBase-DbMapper based model?

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问题 I'm developing a RESTful web application -- Apigility driven and based on the Zend Framework 2. For the model layer I'm using the ZfcBase DbMapper. The model essentially consists of two entities: Project and Image ( 1:n ) and is currently implemented like this: ProjectCollection extends Paginator ProjectEntity ProjectMapper extends AbstractDbMapper ProjectService implements ServiceManagerAwareInterface ProjectServiceFactory implements FactoryInterface The same structure for Image . When the

What exactly is the difference between a data mapper and a repository?

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问题 Well I've been trying to find out the difference between data mapper and repository, but up to now I still have not. It seems to me that the expert programmer said "Repository is another layer of abstraction over the mapping layer where query construction code is concentrated". It seems understandable but is still somewhat very abstract. I read this article on stackoverflow before, and it just made me even more confused: How is the Data Mapper pattern different from the Repository Pattern? I

Datamapper into String

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问题 I want to be able to see the string like the TwitchTV name I have in my database. Here is my current code get '/watch/:id' do |id| erb :mystream @result = Twitchtvst.all( :fields => [:Twitchtv ], :conditions => { :user_id => "#{id}" } ) puts @result end result in terminal; #< Twitchtvst:0x007fb48b4d5a98 > How do I get that into a string (TwitchTV answer in database) Opppppsss! Here is the real code sample. Sorry! get '/livestream' do erb :livestream @users_streams = Twitchtvst.all puts @users