I am attempting to do some calculations on a simple ruby screen.
Lets say for fun, i want to create a form that lets the user convert meters to feet.
Of course I don't want to store the values in a database. Nor would I want to create a table just for this.
So my question.. How do I create a single text field tied to a controller.
With a button.
Here's a really simple example of making a form adding two numbers:
rails new math_app -O
cd math_app
rails generate controller Add form result
The last line generates a controller with 2 actions -
"form"- to show the form
"result" - to show the results
In another command prompt window, open the 'math_app' directory and start the server:
rails server
You can open a browser to 'localhost:3000/add/form' and 'localhost:3000/add/result' to see the default pages Rails generated for you. As you edit things below you can revisit these pages (and don't even have to restart the server) to see what they produce.
Edit 'app\views\add\form.html.erb' to create the form we want to show.
<%= form_tag add_result_path do %>
<%= number_field_tag :first %>
+
<%= number_field_tag :second %>
<%= submit_tag "add" %>
<% end %>
Edit 'config/routes.rb' to make the 'result' action take POST requests from the form above.
Change -
get "add/result"
to-
post "add/result"
Edit 'app\controllers\add_controller.rb' result method to retrieve the two numbers from the form data and add them together.
def result
#first = params[:first].to_i
#second = params[:second].to_i
#result = #first + #second
end
Edit 'app\views\add\result.html.erb' to show the result.
<%= #first %> + <%= #second %> = <%= #result %>
<br/>
<%= link_to 'back', add_form_path %>
Done!
check out form_tag http://api.rubyonrails.org/classes/ActionView/Helpers/FormTagHelper.html#method-i-form_tag
Ruby on rails uses MVC ideology a lot; however you aren't required to save everything to a database form_tag allows you to create an HTML form without tying it to a model.
Related
I have a edit form that prepopulates with the current values. Its a custom edit screen (not the default one that rails uses) and what Im using it for is for users to submit changes that will get voted on and might eventually get applied to the record. However, in the time it takes to be voted on something else might have changed and I dont want to overwrite the changes if they didnt submit a change.
EDIT: Changing to my more specific case so hopefully answers will work for it...
I have the following tables: Recipes, RecipeIngredients, RecipeSteps, RecipeChanges. On the show view of my recipes it displays all the ingredients/steps and there is a tab that then changes just the ingredients/steps to forms as to allow the user to submit changes. I dont want these changes applied though. Instead Im trying to create a voting system where people can vote on them. So what I have decided on is to convert the parameters from the form into a json string and save it in the RecipeChanges table under a single column (instead of using two table for ingredient changes and step changes). Heres the code for the form (html removed to make it easier to see the rails stuff):
<%= form_for #recipe, url: recipe_recipe_changes_path(#recipe), html: {method: "post"}, remote: true do |f| %>
<%= f.fields_for :recipe_ingredients, f.object.recipe_ingredients.order(:order) do |ff| %>
<%= ff.hidden_field :order, class: "position" %>
<%= ff.text_field :ingredient, placeholder: "Add Ingredient (e.g. 3 cups cooked rice)" %>
<label><%= ff.check_box :_destroy %>Remove</label>
<% end %>
<%= f.fields_for :recipe_steps do |ff| %>
<%= ff.hidden_field :order, class: "position"%>
<%= ff.text_area :step %>
<label><%= ff.check_box :_destroy %>Remove</label>
<% end %>
<%= submit_tag "Submit", class: "button" %>
<% end %>
So this sends a recipe object to my RecipeChange controller and there I handle the params to save them as the json string like so:
def create
#change = RecipeChange.new
#change.recipe_id = params[:recipe_id]
#change.new_recipe = recipe_change_params.to_json
#if #change.save
#add alert for successfully adding
#else
# add code for error handling
#end
end
This works like I want except for it saves all the ingredients/steps and I would like to only save what they have changed. I had two thoughts on how to do this but not sure how to accomplish it.
Check if the fields have changed when they click the submit button and only send the ones that have been edited (not sure if possible)
In the controller grab the original recipe (I have the id so that would be easy) and loop through the ingredients/steps and compare them and remove any that are identical....this is the method I think would be better but not sure how to loop through the hashes to accomplish this
Have a look at ActiveModel::Dirty. http://api.rubyonrails.org/classes/ActiveModel/Dirty.html#method-i-changed
You can do something like:
changes = bag.changed_attributes and get a hash of that attributes that changed, and then save those with bag.update_attributes(changes), for example.
This is a bit old now but I've come across the same or similar scenario and wanted to share for others.
In my case I populate some nested form fields based on an existing object in my #new action. However, in my #create action I did not want to save these nested form params unless they were actually modified compared to the original existing object.
In this case, ActiveModel::Dirty would always be true as it would compare [nil, "value"].
I first tried to modify the params in my #create action and compare them to the original existing object similar to this discussion but this got messy and felt wrong.
I ended up saving all records then doing a cleanup with an instance method in my model that I call after save in my controller's #create action. Still feels a bit dirty but it's working.
Example:
# controllers/changes_controller.rb
# ChangeController#create
def create
# ... shortened for example ...
if #instance.save
#instance.remove_clean_changes
format.html
end
end
# models/change.rb
# Change#remove_clean_changes
# Loop over all original objects and compare the necessary attributes
# to the changes. If they match, they are clean and should be deleted.
def remove_clean_changes
original_objects = self.original_objects
changes = self.changes
original_objects.each do |original_object|
changes.each do |change|
change.destroy if (change.attribute_one == original_object.attribute_one &&
change.original_object_id == original_object.id)
end
end
end
I have a controller for customer. In the new action, I redirect to another page, which belong to the pages controller
class CustomersController < ApplicationController
def new
redirect_to register_path
end
Would it be possible to create the object in the registration action like this?
class PagesController < ApplicationController
def registration
#customer = Customer.new
end
end
I believe the setup is something like this: you have models in your application for a Customer and, say, an Agent. Your website users register as either and the desire is to have a single HTML page (URL) with both options available. They choose which one they are and submit some fields, say name/email/password. To keep it simple, without bothering with JavaScript to hide things behind tabs, you have something like:
**Customer**
Name: ___________
Email: __________
Password: _______
[Submit]
**Agent**
Name: ___________
Email: __________
Password: _______
[Submit]
You have a few options here to avoid your guilty feeling in the Rails controllers:
Go heavy client-side JavaScript. Don't have the new actions on the controllers. The JavaScript creates the page elements. The create action becomes a JSON API endpoint, thereby avoiding the problem in the Ruby application. This is obviously a significant architectural deviation from where I think you are today.
Use a little bit of JavaScript to dynamically load the correct 'partial' into the DOM when the user switches between the options. Avoids the underlying problem in the question by effectively separating the 'pages' out to the two controllers. The Pages→registration action does not need to set any instance variables for the view. The JavaScript deals with the partial loading. (see 'link_to' and the 'remote' option)
Don't include both forms in the same HTML page, just default to one, say the Customer one, and provide a link to navigate to the Agent one, e.g. a link in a tab, or a plain link like "Not a Customer? Register as an Agent." In this scenario, you have a neat mapping to the Ruby MVC design, each of the pages are just the new action of its relevant controller. The downside is a page load to change between the two options. This is the simplest, plainest choice … if you can get the boss to agree to the UX. PS: if you are using turbolinks, then the 'feel' of this option in the browser will be not far from option (2).
Stick to your design
Keep in mind that you will have difficultly dealing with error conditions and messages with option (4). You can do it, but the code won't be simple or easy to maintain.
If option (4) is a must, one simplification can be the create actions on each of the controllers rendering their own new in case of an error. If you submit the 'Agent' form from your starting page, with errors, to the Agents→create action, that action finishes with a render 'new' to show the user the Agents→new page. No 'customer' form is visible. You could then add a sprinkle of option (3) in there with a "Not an Agent? Register as a Customer." link under the form. Doing this greatly simplifies your error handling.
Which then leads to a suggestion for your original problem. Cheat. Don't have an #customer instance variable for the new actions (or the registration action). Use partials for the customer and agent forms, and pass in a new object to form_for, e.g.
pages/registration.html.erb
<%= render 'customers/new_form' %>
<%= render 'agents/new_form' %>
customers/new.html.erb
<%= render 'customers/new_form' %>
customers/_new_form.html.erb
<% form_for Customer.new do |f| %>
<%# include the inputs shared with the edit action %>
<%= render 'fields', f %>
<%= f.submit %>
<% end %>
customers/_fields.html.erb
<%# 'f' is one of the locals passed to the partial %>
<% f.input_field :name %>
<% f.email_field :email %>
<% f.password_field :password %>
customers/edit.html.erb
<% form_form #customer do |f| %>
<%= render 'fields', f %>
<%= f.submit %>
<% end %>
… then you would follow the same pattern for:
agents/new.html.erb
agents/_new_form.html.erb
agents/_fields.html.erb
agents/edit.html.erb
I want to create the following:
The user types a text into a TextField and clicks 'submit'.
The text is then given to my ruby application which modifies certain bits of it and then displays it on the website.
The problem I am having is that I do not know how to create this textfield and how to access the content of that textfield in my application.
(All the tutorials I have looked at that use forms use a Model. Michael Hartl in chapter 7 for example writes signup page and just uses user/new as his signup page. Do I have to create a Model for my textfield as well then? It seems a bit over the top to create a model just for a simple form?)
You can just use form_tag helper to create form not connected to any model like:
<%= form_tag '/some_action_url' do %>
<%= text_field_tag 'my_field' %>
<%= submit_tag 'Send' %>
<% end %>
You can grab value of text field from params[:my_field] in your controller.
I am very new to Rails.
I am looking for the most common and 'rails-like' way to display the output of form data. I know that Simple form and Formtastic are good options to write concise code and display input fields in a user friendly manner. However, I am looking for something slightly different, I want to display the data from these forms as output, and I want to do it in a similar and concise manner. I haven't been able to find anything the last few days that I have been searching around so I figured I should ask Stack Overflow.
What do you normally do:
Write custom helpers to be able to write concise code and display the output data?
Use Simpleform/Formtastic, disable the fields, and modify the css to
make it look the way you want?
Is there a common gem that does this? Or perhaps another way I haven't thought about.
First, thanks for the initial responses. I thought I should clarify my question. Since the answers don't quite hit the mark. I already have a show method in the controller, as well as a view template for it. Currently I am displaying each field individually in the form for about 12 fields using form_for. See example snippet below:
<%= form_for(#event) do |f| %>
<div class="row-fluid">
<div class="span6">
<%= render 'shared/error_messages' %>
<%= f.label :title %>
<%= f.text_field :title, :disabled => true %>
<%= f.label :start_date %>
<%= f.date_field :start_date, :disabled => true %>
</div>
</div>
<% end %>
I guess maybe a better question would be, is their an equivalent to form_for method that display data for users, not to edit it but just to read it? It seems like their would be a a standard way to do it that I haven't discovered.
The easiest way to build forms is to use rails g scaffold Example name:string This would generate the Model, Views, Controller, and the necessary database migrations for a Model named Example with a Name attribute that is a string.
You would then use html and css to style the view how you want.
There is a ton of useful info for you on the rails guides here.
Although this question is rather ambiguous, you must appreciate that this functionality is exactly what Rails is built for (submit data & be able to display / manipulate it somewhere else)
Data
The data in an MVC application is bound by one very important factor - a database
If you're submitting data through a form, your goal is to store it in your database, and display it in other views / controller methods
Therefore, the blunt question to your answer is to abide by MVC processes, and save your data to a central repository (database or other), which you can call later:
View
To get your data into your data store, you first need to submit it
The view part of MVC is where you can display your UI, and consequently is where you can put your form. There is a whole tutorial about how to design this here, but for demonstrations' sake, here's an example of how you'd use your form:
#app/views/posts/new.html.erb
<%= form_for #post do |f| %>
<%= f.text_field :title %>
<%= f.text_field :body %>
<%= f.submit %>
<% end %>
Controller
The data you input into your view will be sent to your controller on save
The data is sent via the HTML POST method to be read by Rails as a params[] hash. This hash contains all the sent items from your HTML form, and can be used like this:
#app/controllers/posts_controller.rb
def new
#post = Post.new
end
def create
#post = Post.new(post_params)
#post.save
end
private
def post_params
params.require(:post).permit(:title, :body)
end
Model
The .save method on your newly created Post object, basically tells your model to put the data into your database (or other data store), which you can then pull later (using the .find method or similar)
#app/models/post.rb
Class Post < ActiveRecord::Base
#stuff here
end
It's important to note your models don't store your data, they simply provide an interface (API if you will) to save the data into some sort of data store (namely, a DB)
Models are super important because they allow you to structure & relate your data, creating the ability to deploy really deep & powerful applications
What's the best way to create a related set of checkboxes in Ruby on Rails? In the ToscaWidgets library used by Turbogears you can do the following:
twf.CheckBoxTable('arbitrary_numbers',
num_cols=5,
options=['1','2','3','4','5','6','7','8','9','10']),
This generates 10 labeled checkboxes in two rows of 5 checkboxes. I'm trying to duplicate this in Rails without just creating 10 separate checkbox controls. No big deal, just hoping for a clean way to do this.
Something like this:
<% 10.times do |i| %>
<%= label_tag i %>:
<%= check_box_tag "alternate_numbers[#{i}]" %> <br />
<% end %>
will produce 10 checkboxes and if you will put it into form and submit it, you will have access to it in params[:alternate_numbers][index] where number is your number. You can put it into helper and call many times. You can also add some parameters to helper to customize output.