How to sanitize sql fragment in Rails

Question

I have to sanitize a part of sql query. I can do something like this:

class << ActiveRecord::Base
  public :sanitize_sql
end

str = ActiveRecord::Base.sani         


        

Answer 1

This question does not specify that the answer has to come from ActiveRecord nor does it specify for which version of Rails it should be. For that reason (and because it is one of the top and few) answers on how to sanitize parameters in Rails...

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Here a solution that works with Rails 4:

In ActiveRecord::Sanitization::ClassMethods you have sanitize_sql_for_conditions and its two other aliases:  sanitize_conditions and sanitize_sql. The three do literally the exact same thing.

sanitize_sql_for_conditions

Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a WHERE clause.

Also in ActiveRecord you have

sanitize_sql_for_assignment which

Accepts an array, hash, or string of SQL conditions and sanitizes them into a valid SQL fragment for a SET clause.

• The methods above are included in ActiveRecord::Base by default and therefore are included in any ActiveRecord model.

See docs

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Also, however, in ActionController you have ActionController::Parameters which allows you to

choose which attributes should be whitelisted for mass updating and thus prevent accidentally exposing that which shouldn't be exposed. Provides two methods for this purpose: require and permit.

   

params = ActionController::Parameters.new(user: { name: 'Bryan', age: 21 })
req  = params.require(:user) # will throw exception if user not present
opt  = params.permit(:name)  # name parameter is optional, returns nil if not present
user = params.require(:user).permit(:name, :age) # user hash is required while `name` and `age` keys are optional

The "Parameters magic" is called Strong Parameters (docs here) and you can use that to sanitize parameters in a controller before sending it to a model.

• The methods above are included by default in ActionController::Base and therefore are included in any Rails controller.

I hope that helps anyone, if only to learn and demystify Rails! :)