Rails 4 Activerecord Typeerror Nil Is Not a Symbol

rails 4 activerecord TypeError nil is not a symbol

While I still believe this is a bug in active record, I was able to get around it with the https://github.com/rails-api/active_model_serializers gem. This gem overrides to_json eliminated the need for the bug code in active record to be called.

anyone else have a better answer?

Updated Controller:

class V1::DealsController < ApplicationController

    def by_mall_id
      deals = Deal.where(mallid: params[:id]).first
      render json: deals, serializer: V1::DealSerializer
    end

end

My new DealSerializer:

class V1::DealSerializer < ActiveModel::Serializer
    attributes :MALLID

    def MALLID
      object.mallid
    end

end

TypeError: nil is not a symbol

Ok I finally found the answer. I made the join table, 'entries' without an id field. This is require if using the join table as a model with extra data on it.

Rails - TypeError: nil is not a symbol nor a string, when updating

If you are trying to update the record in a dependent model, it possibly has only a foreign key, but no primary key. The problem can be solved if you add a line self.primary_key like this:

class YourDependentRecord < ApplicationRecord  
  self.primary_key = 'user_id'
end

where 'user_id' is the primary key in the master model.

Rails: Trying to update an attribute on a join table | getting TypeError: nil is not a symbol nor a string

I believe the join table is not mean to have a primary key when you're using HABTM.

Since you're storing data on the join table you are, appropriately, using has_many :through. In this case, you should use a proper table (including id) for the join table.

BTW, I would think your join model might be UserAssignment with the table being user_assignments which, IMO, reads a little more naturally. In which case, you would do:

class Assignment < ActiveRecord::Base
  has_many :user_assignments
  has_many :assignees, through: :user_assignments, source: :user
end

class User < ActiveRecord::Base
  has_many :user_assignments
  has_many :assignments, through: :user_assignments
end

class UserAssignment < ActiveRecord::Base
  # == Schema Information
  #  completed_on :datetime
  belongs_to :user
  belongs_to :assignment
end

Rails 4 to_json produces unexpected Exception nil is not a symbol

The view backing my QuestionAnswerResponse model does not have an id column and I was not setting a primary key in the model. In the capacity that I use this model I do not need a primary key; this is a read only view used to more easily access some complex key/value pairings directly instead of through more complex logic.

In Rails 3 this worked fine; in Rails 4 when you access a model without a primary key you end up with an attribute that looks like this in your hash nil => nil

The problem is actually up at the ActiveRecord level, but wasn't actually causing a problem until I attempt to do json serialization; at which point in time an attempt is made to call nil.to_sym which raises the exception.

This seems like a bug in ActiveRecord to me; but for now I have worked around it by manually setting a primary key on my model.

TypeError : nil is not a symbol render :json

I solved this issue , this caused because of there is no primary key in the table ,

This worked after i add primary key in the model

class Supplier < ActiveRecord::Base
    self.primary_key = 'id'
   ......
   .... 
end 

Rails Polymorphic Association, causing 'nil is not a symbol' TypeError from form_for when trying to create new

The problem was some of the tables had :id => false. Let this be a warning to would be users of db:schema:dump

How to conditionally avoid 'nil can't be coerced into Integer' error

Because some of the account records have nil amount, you can convert them to integer by calling to_i or to float by to_f, here account.amount is returning nil somewhere, do this

account_total += account.amount.to_i

It will resolve the error. But since amount is a numeric column, you should better set the default value as 0 in migrations at DB level.

or, use sum

account_total = @user.accounts.sum(:amount)

It avoids nil values and runs a SQL sum

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