I want to check user input in a form before submit. Is there a standard way to do this in Rails?
You will want to use validation checks.
http://guides.rubyonrails.org/activerecord_validations_callbacks.html
Älphä Blüë wrote:
You will want to use validation checks.
http://guides.rubyonrails.org/activerecord_validations_callbacks.html
This is the Active Record validation. I am looking for something like Action Controller validation( I am not sure whether rails has this feature). I want to validate the user input in the web form when user clicks sumbit button.
Zhao Yi wrote: [...]
This is the Active Record validation. I am looking for something like Action Controller validation( I am not sure whether rails has this feature). I want to validate the user input in the web form when user clicks sumbit button.
If you set up the validations in the model, Rails will validate form submissions just as you are describing. Try it!
Best,
Älphä Blüë wrote:
So, the first question you have to answer is what type of form are you using? If you are using a form_for then that's backed by a model and you can use validation checks. If you are using form_tag then that isn't backed by a model and there are other ways of checking, depending on what you are using.
Example: I have a form_tag that works with an ajax widget so I can actually create a validation method using javascript and call the validation on submit.
I use form_tag. How can I do the validation? Do you mean I have to write it in javascript? Does Rails have a validation helper on this?
thanks.
Hey mate, so I wish I could give you a lot of advice on this but I'm
getting my feet wet on similar issues. 
The best practices you should remember is that you use form_for when you are doing inserting of rows or data (create/edit) etc. and form_tag is just for creating normal forms.
Because it doesn't have a model, from my understanding you have to call a validation method either one of two ways:
1) with a validation check via javascript like so:
<% form_tag your_controller_path, :method => 'get', :onsubmit => 'return validate(this)' do %> form.... <% end %>
The validate() would be a javascript validation method that would return true or false depending on the criteria you are testing.
2) you could also use the config/initializers folder to write your ruby code as helpers and apply code that will disable the submit button until the conditions are properly met or something similar. Here's a good example of that:
http://www.webficient.com/2008/10/18/easy-rails-patching
However, as always (when someone like me who is also new) answers
questions, someone with a lot more experience with rails might come
along and teach us both something new.
Marnen is a really good expert and has helped me out a ton in the past. If he says you can do the validation checks in the model, it might possibly be that you can. I haven't found a way to pass the validation checks to the model without using a form_for tag though...
Zhao Yi wrote: [...]
I use form_tag. How can I do the validation?
The easiest way would be to use form_for, in which case Rails will do the validation automatically. I'm not sure if there's an automatic method with form_tag.
Best,
If what you want is to validate the form on the browser you'll need Javascript. In any case you'll need to also validate it in the server because anybody can fake a page with appropriate modifications to try and hack your app., completely bypassing any validations you might put in place with Javascript.
Pepe
OK, I understand. Thanks all your help.