Mongoid介绍

jieforest

Now, let's create the Address model with a number of fields and relations.

1. $ rails generate model Address
   
2. class Address
   
3.   include Mongoid::Document
   
4. 
   
5.   field :street, type: String
   
6.   field :city, type: String
   
7.   field :state, type: String
   
8.   field :zipcode, type: String
   
9.   field :country, type: String
   
10. 
    
11.   embedded_in :author
    
12. end
    

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Now, let's test the code that we have written.

Note

Did you notice that we are not using the hash rocket (=> notation for defining the hash of options for the field method? Instead of :type => String, we are using the JSON notation instead. We shall follow this standard throughout the book.

jieforest

Testing the models

Now that we have created the models, let's test it out quickly:

1. irb> a = Author.create(name: "Charles Dickens")
   
2. => #<Author _id: 5143678345db7ca255000001, name: "Charles Dickens">
   
3. 
   
4. irb> a.create_address(street: "Picadilly Circus", city: "London", country: "UK")
   
5. => #<Address _id: 514367f445db7ca255000003, street: "Picadilly Circus", city: "London", state: nil, zipcode: nil, country: "UK">

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As we can see, this creates an Author object and its corresponding Address object. Mongoid includes ActiveModel and you may notice the similarity in these methods if you have used ActiveRecord.

Tip

We have used create_address because an author has only one embedded address. If, an author had multiple addresses, we would have used a.addresses.create.

jieforest

1. irb> Author.first
   
2. => #<Author _id: 5143678345db7ca255000001, name: "Charles Dickens">
   
3. 
   
4. irb> Author.first.address
   
5. => #<Address _id: 514367f445db7ca255000003, street: "Picadilly Circus", city: "London", state: nil, zipcode: nil, country: "UK">

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Here, we have double-checked that the author is indeed persisted to the database. Since this is MongoDB, we can dynamically add attributes to the object!

jieforest

1. irb> a['language'] = "English"
   
2. => "English"
   
3. 
   
4. irb> a.save
   
5. => true
   
6. 
   
7. irb> Author.first
   
8. => #<Author _id: 5143678345db7ca255000001, name: "Charles Dickens", language: "English">

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Introducing Moped

So, let's see what happened in Mongoid and MongoDB. First, let's see what is in the log file development.log under log.

jieforest

When we issued the command Author.create(name: "Charles Dickens"), it generated the following output:

1. MOPED: 127.0.0.1:27017 INSERT       database=sodibee_development collection=authors documents=[{"_id"=>"5143678345db7ca255000001", "name"=>"Charles Dickens"}] flags=[] (0.2460ms)

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Now, when we issued the second command a.create_address(street: "Picadilly Circus", city: "London", country: "UK"), it updated the Author object, and created an embedded Address document as seen in the following line:

1. MOPED: 127.0.0.1:27017 UPDATE       database=sodibee_development collection=authors selector={"_id"=>"5143678345db7ca255000001"} update={"$set"=>{"address"=>{"_id"=>"514367f445db7ca255000003", "street"=>"Picadilly Circus", "city"=>"London", "country"=>"UK"}}} flags=[] (0.1211ms)

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