I have a mongodb database with a single collection containing 400+ entries of basic data.
I'm using Rails and the mongoid gem to link the two together however when I query my model in the rails console there are no entries found.
QuizQuestion.first
Yields no results
My model:
class QuizQuestion
include Mongoid::Document
field :question, type: String
field :correctAnswer, type: String
field :wrongAnswers, type: Array, default: []
field :category, type: String
end
I have configured the mongoid.yml configuration file to point to the address of the database.
Does anyone know how to correctly do this or where I'm going wrong?
The reasons why you see no result:
1) database config is incorrect and you are pointing to a different database on the same mongodb instance
2) class name does not match the name for the collection within mongo. Open up a console/terminal and type:
mongo
then type this:
show dbs
This is the name of the dbs you need in the first part
use x
Where x is the db name
show collections
This will list the names of the collections.
Once you have the name of your collections, you can add this to your model:
store_in collection: "name_of_collection_as_in_mongo"
Therefore if the name of your collection was quiz_question as shown in the mongo client you can do this on your model:
class QuizQuestion
include Mongoid::Document
store_in collection: "quiz_question"
field :question, type: String
field :correctAnswer, type: String
field :wrongAnswers, type: Array, default: []
field :category, type: String
end
The reason you are not seeing any records (if you are pointing at the correct db name) is most likely due to mongoid expecting the class name to equal a pluralised collection name so QuizQuestions == quiz_questions within mongo
Related
I currently have the columns id, name, email, linkedin, company, contacted, recruiter, student and I want to add a new one called responded. I'm only finding answers on how to add new columns to all the existing instances in my db. So I did try this:
db.people.update({}, {$set: {"responded": false}}, false, true)
All my existing instances have a field :responded set to false by default. When I try to add a new person now I'm getting this error:
Mongoid::Errors::UnknownAttribute in PeopleController#create
message: Attempted to set a value for 'responded' which is not allowed on the model Person. summary: Without including Mongoid::Attributes::Dynamic in your model and the attribute does not already exist in the attributes hash, attempting to call Person#responded= for it is not allowed. This is also triggered by passing the attribute to any method that accepts an attributes hash, and is raised instead of getting a NoMethodError. resolution: You can include Mongoid::Attributes::Dynamic if you expect to be writing values for undefined fields often.
MongoDB does not have "columns", it does not have tables either. You have documents with fields.
I imagine you are using MongoID for your models, so you only need to define the field on your model
class Person
include Mongoid::Document
field :first_name, type: String
field :middle_name, type: String
field :last_name, type: String
field :responded, type: Boolean # something like this
end
https://docs.mongodb.com/mongoid/current/tutorials/mongoid-documents/#fields
I'm trying to create some relations on Mongoid but when I try to save the inner object or add it to the user.personal_accounts collection I get the following error
NoMethodError: undefined method `bson_type' for #<Bank:0x71c01a8>
My Object in rails console is correct
#<PersonalAccount _id: 56e87f669c27691be0d3041b, number: "55", active: true, bank: #<Bank _id: 56d74cdb9c27692fb4bd4c6d, code: 123, name: "Bradesco", country: "USA">>
My mappings
class PersonalAccount
include Mongoid::Document
field :number, type: String
field :active, type: Boolean
field :bank, type: Bank
embedded_in :user
end
class User
include Mongoid::Document
field :first_name, type: String
field :last_name, type: String
embeds_many :personal_accounts
end
class Bank
include Mongoid::Document
field :code, type: Integer
field :name, type: String
field :country, type: String
end
The mapping that I was expecting is:
User
PersonalAccounts
Bank
Bank
As I have read that I need to copy the outer bank to each PersonalAccount.
I have already tried the following Link
Versions installed:
bson (4.0.2)
bson_ext (1.5.1)
mongoid (5.0.2)
mongo (2.2.4)
The root of your problem is right here:
field :bank, type: Bank
MongoDB doesn't know how to store a Bank so Mongoid will try to convert it to something that MongoDB will understand while Mongoid is preparing the data for the database, hence the NoMethodError.
Presumably you want Bank to exist as its own collection and then each PersonalAccount would refer to a Bank. That would be a standard belongs_to setup:
class PersonalAccount
#... but no `field :bank`
belongs_to :bank
end
That will add a field :bank_id, :type => BSON::ObjectId to PersonalAccount behind the scenes and hook up accessor (bank) and mutator (bank=) methods for you.
Normally you'd want the other half of the relation in Bank:
class Bank
#...
has_many :personal_accounts
end
but that won't work (as you found out) because PersonalAccount is embedded inside User so Bank can't get at it directly. Keep in mind that embeds_one is just a fancy of wrapping the Mongoid machinery around a Hash field in a document and embeds_many is just a fancy way of wrapping the Mongoid machinery around an array of hashes inside another document; embedded documents don't have an independent existence, they're just a part of their parent.
Here's my use case:
I've got a collection full of sales tax rates that have been imported from CSV files. I created the Mongoid model to mirror the field names (these are not changeable):
class SalesTaxRate
include Mongoid::Document
field :state, type: String
field :zip_code, type: String
field :tax_region_name, type: String
field :tax_region_code, type: String
field :combined_rate, type: Float
end
Next, I'm building a model for use in my app. Let's say I want to create something called a Location:
class Location
include Mongoid::Document
field :name, type: String
field :street, type: String
field :city, type: String
field :state, type: String
field :zip_code, type: String
end
I'd like to be able to get a location's sales tax rate simply by calling something like this:
home = new Location(...)
home.sales_tax_rate
I'll never be setting the rate via home, just looking it up.
What's the "right" way to do this? I can think of two approaches -- the simple way seems to be just to define a method that does the lookup, as so:
class Location
...
def sales_tax_rate
SalesTaxRate.where(zip_code: self.zip_code).first.combined_rate
end
And this works. But I'm wondering whether I should be using a belongs_to association and, if so, why and how best to do that.
Still learning the ropes here, so apologies if this is a novice/silly question. Many thanks in advance!
If you have an index on zip_code in model SalesTaxRate what you are doing is essentially the same as what belongs_to will do. Just have a nil check in your code to ensure that it doesn't fail:
SalesTaxRate.where(zip_code: self.zip_code).first.try(:combined_rate)
# or
rate = SalesTaxRate.where(zip_code: self.zip_code).first
rate.nil? ? nil : rate.combined_rate
If you still want to go belongs_to route, you can define zip_code to be the identity in your SalesTaxRate. But you should take care of few things if you do that: First, all the zip codes in imported data need to be unique. Second, your location model can not have any zip code which is not available in SalesTaxRate otherwise you will face issues.
I started to use the mongoid gem in my project, and I'm a little confused about how it store and get the information on the database. I have fields of specifics types in my models, but when I get it from the DB it returns a Hash.
Here is my models:
service.rb
class Service
include Mongoid::Document
field :username, type: String
field :strategy, type: Strategy
field :design, type: Design
end
strategy.rb
class Strategy
include Mongoid::Document
field :name, type: String
field :description, type: String
field :resources, type: Resources
field :scalability, type: Scalability
field :localization, type: Localization
field :contact, type: Contact
end
If I initialize a new service #service, and do #service.class it returns Service, the right one, but if I try do #service.strategy.class, it returns Hash, and not Strategy, like I was expecting. I read on the mongoid manual there are the "Custom field serialization", what I think allows me to do what I want. But I was wondering if there are not any other way to do that easily, because I have lots of models to change.
So, I am having some issues with user authentication in embedded documents. I have two documents, one embedded in the other. A business has many members. The models look like this:
class Member
include Mongoid::Document
field :username, type: String
field :password, type: String
embedded_in :business
validates :username, :presence => true, :uniqueness => true, :length => 5..60
end
class Business
include Mongoid::Document
field :name, type: String
embeds_many :members
end
The problem is that it isn't validating the username's uniqueness in each model. When I save a member within a business, I can save a thousand of the same name. This of course is not going to work for a good authentication system. I am using Mongoid 2, Rails 3, and Ruby 1.9
This is a normal behavior when using embedded documents as explained here: MongoID validation
validates_uniqueness_of
Validate that the field is unique in the database: Note that for
embedded documents, this will only check that the field is unique
within the context of the parent document, not the entire database.
I think you want to try to create an Index in the username field that would ensure uniqueness among all the objects of that collection. Something like this:
ensureIndex({username:1},{unique:true});
EDIT: If you want Mongo to throw exception if a document with the same index value exists, you must avoid Mongo to do the “fire and forget” pattern. This means that the database will not wait for a response when you perform an update/write operation on a document.
And you want to pass this parameter: safe:true. By doing so Mongo should raise an exception if for any reason the document can't be inserted.