How to Test If Parameters Exist in Rails

How to test if parameters exist in rails

You want has_key?:

if(params.has_key?(:one) && params.has_key?(:two))

Just checking if(params[:one]) will get fooled by a "there but nil" and "there but false" value and you're asking about existence. You might need to differentiate:

• Not there at all.
• There but nil.
• There but false.
• There but an empty string.

as well. Hard to say without more details of your precise situation.

Rails check if params exist in the controller

The problem is this line params.require(:primary) saying that the parameter is required, so attempting to do like params.require(:primary).exists? wont help you if you do not have a :primary param at all because the require already failed.

You need to check its existance on params itself. For example params.has_key?(:primary).

Dependening on your use case, you might also use params.permit(:primary) directly on params as well. See the API docs for detailed information on how ActionController::Parameters (the class for params) can be used.

http://api.rubyonrails.org/classes/ActionController/Parameters.html#method-i-permit

How to check if params[:some][:field] is nil?

 if params[:report] && params[:report][:start_date] && params[:report][:end_date]

How to check if nested params exist?

If you're using Ruby >= 2.3.0, you can make use of Hash#dig:

params.dig(:q, :category_id)

How to check the existence of a key in params in Rails?

You can not rely on params[:page], you need to make sure that the value exists. Moreover, since you are trying to add an integer, you also need to make sure that the type matches.

if params.has_key?(:page)
  current_page_count = params[:page].to_i
end

So you can use the method: has_key? to ensure that the value of :page exists in params.

How to check if value exists in params.permit?

You should add validations to your model.
From your question i understand that you want to save details only if you get values in all the field, if not you don't want to save, right?. If yes, then adding validations to your model will give you what you wanted.

Add the following to your organization model

validates_presence_of :name
validates_presence_of :description
validates_presence_of :copyright

by doing so, the user won't be allowed to save the details unless and until all three fields have some value in it.

There is no need to use delete as the incomplete information will not be saved.

for more and advanced info click here

how to check for existence params in view

Views should NOT know about params.
In controller (or view helper) create variable like `


if params[:publication]
@selected = params[:publication][:category]
end

or even do it in 1 line

@selected = params[:publication].try(:[], :category)

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