Rails - generate Scaffold with Table Options - ruby-on-rails

I've started learning Ruby last week, and I've started learning Rails today, so bear with me.
I see that Rails come with generators that allow you to generate models/controllers or even model+controller+views bundle as 'scaffold'. This is what I am interested in.
However, I have a question. How do I set database options of the column?
eg. To generate a users table I would do:
rails g scaffold users uuid:binary name:string email:string password:binary registered_on:date number:integer default:string
Now what if I'm integrity freak and am not happy by having validation just in model/controller, but want to do database level limitations as well.
What if I want email to be 50 characters max, and number to Auto-Increment and neither of all fields is allowed to be NULL and default field must have a default of 'foo'. Is there any way to pass these requirements to generator command?
I know its possible to set these options in .rb file that is used in rake db:migrate, however it would be easier to just pass values in with 1 command.

At least some things are available, like string length, but not sure about the others.
rails g scaffold users email:string{50}

Use type modifiers between curly braces, example:
rails generate migration AddDetailsToProducts price:decimal{5,2}
More info: migrations
Use scaffold and obtain generic migration files. And, as you mentioned, do the customizations in there. This files are found in db/migrate.
After you are done customizing the fields, don't forget to do a rake db:migrate.

Related

Add column to migration when using compound model name?

I have a model called MyArticle. When I try to use the command
rails generate migration AddtestToMyArticle test:string
the migration file contains only empty up/down methods. Having done this previously on a single word model name, it worked just fine and the migration up/down methods had the appropriate code.
I tried "AddtestToMy_Article" but that didn't work either. What do I need to do to work with my compound model name and the generate migration command?
You need to use
rails generate migration AddColumnToMyArticle test:string
When using 'AddColumn' you will have the appropriate code in your migration.
I just looked back over this, and while my answer is correct, it's better to have a more descriptive migration name. The user below who noticed the capitalization is right in that if you don't have each new word capitalized, Rails won't pick up on what exactly you're trying to do. So, in your question you have AddtestTo... but it should be AddTestTo....
It seems to work if you use underscores rather than CamelCase
rails g migration add_test_to_my_article test:string
Hope this helps
rails generate migration AddNewFieldToMyArticle new_field:string

Access Migrations via console in Ruby on Rails

I am new to Ruby on Rails . This might be a very foolish question.
I have created a migration using
rails generate migration Kapol name:string position:integer
rake db:migrate
Then using phpmyadmin i copied the database already present
I then opened up rails console
My question is can i use the method Kapol.find(1)??
because when i tried it using singular or plural it says
unitialized constant:Kapol
I know that there has to be a method but where to specify it?
You must generate a model in case to create a table for it, because the migration is usually used to modify existing tables.
It might be confusing that the model generator also creates migration file in your migrations folder. The only difference is that the model generator also generates initial code to create table, on the other hand, the migration generator creates only migration file without initial code.
rails generate model Kapol name:string position:integer
More information: http://guides.rubyonrails.org/getting_started.html#generating-a-model
If you're very new to Ruby on Rails, probably the best thing for you to do is create a scaffold, which gives you your migration file, your model file, your controller file, and various view files, test files, etc. etc., which all work well together. Then you can play with these and build up from there.
rails generate scaffold Kapol name:string position:integer
If you're happy with the migration that was automatically generated, then rake db:migrate and you're all set.
As Andrew says below, you can also just generate any of those files one at a time by replacing 'scaffold' with 'model', etc.
Your Kapol.find(1) is correct.

How does these rails generate command differ? and what basically rails generate means?

rails generate migration
rails generate model
rails generate scaffold
rails generate controller etc.
How these differ?
According to rails guides:
Using generators will save you a large amount of time by writing boilerplate code, code that is necessary for the app to work, but not necessary for you to spend time writing. That’s what we have computers for.
rails generate commands family used to provide simple and easy way for developer to create different object types.
rails generate migration - creates DB migration script in db/migrations directory so developer can setup his DB.
rails generate model - creates model class with associated migration, test and fixtures (test data).
rails generate scaffold - creates all nedded classes with basic logic and presentaion. It creates controller (with simple CRUD logic), model, fixtures, functional and unit tests.
rails generate controller - creates controller with associated functional tests, helper and basic views templates.
You can read more here: http://guides.rubyonrails.org/command_line.html#rails-generate
They differ in the sense that they generate different stuff.
migration will generate a database migration file,
model will generate a model(with a migration and a spec by default)
scaffold will generate a scaffold of a resource
and controller will generate a controller.
generate means it will create the files for you with boiler plate code already in place(you will still need to edit them though..but scaffold can get you working with a basic application already)
Read more about it here: http://guides.rubyonrails.org/command_line.html#rails-generate
rails generate is a command line script for quickly generating the code for various Rails' constructs.
In the example you give they differ by what they produce, with the first argument being the type of code generated. For example if I wanted to create a User model I would run:
`rails generate model user`
The model file, test file and migration would be created for me.
You should read the Rails' documentation to find more.
**rails generate model user:
The above command create a Template Object that is a mirror image of the database table.
For example, if you have a database table that is named users that has a name:string, and email:string field,then "rails generate model user" create an Object that mirrors that user table with a few addition.
Here are the similarity they both have name:string,email:string the both have the word user.
The difference are few but significant: user is Capitalized in the model name like "User".
The Table add create_by and updated_by automatically.
migration:db create the database mirror using the model as a model.RECURSION ANYONE?

How do I add a field in Ruby on Rails?

I'm new to RoR, and I've just used scaffold to generate a table and create the pages for CRUD operations. Now I want to add a new field to this. One place I found tells me how to do that in the database, but is there a way to do it where it will add the field to all the pages too, or is that just a manual operation and I need to make sure I know all my fields up front?
To add a new column to the database
$ script/generate migration add_fieldname_to_tablename fieldname:string
$ rake db:migrate
To get your views up to date you can run the scaffold again, with your updated list of fields. It will balk on replacing your migrations but you can force it to replace your views.
$ script/generate scaffold tablename fieldname:string old_field_1:string ...
At the prompt answer a and it will overwrite the views, but not the old migration. It also won't modify your existing data.
First you'll write a migration to add the field, run the migration, then you need to rerun the scaffold to regenerate the views, etc. Beware, this will wipe out edited files from before. Of course, instead of scaffolding again you could manually add references to new field where appropriate.
You will have to update your database, no matter what (Remember to 'rake db:migrate' after you create the migration!)
Regarding the interface, you are a bit more lucky: the formtastic plugin makes your views look like this:
The 'f.inputs' is calculating the form fields on-the-fly, based on your model's attributes. This will not cover complex forms that need special treatment, but the usual ones, you will get them automatically.
For an easy-to-understand tutorial, see the latest railcast (Railscast #184, you will have to google for it, I can't post 2 links because I'm not cool enough for stackoverflow yet, sorry).
Railcast #185 is supposed to continue covering formtastic, and it's due to be published next monday.
Needs to be done manually, or the scaffold needs to be regenerated.

Model from existing table in Rails 2

I have a database with tables. I want to create a model in my Rails app from existing table. As i know, such functionality is available, and is done as follows:
script/generate scaffold model_name --skip-migration
Of course, i defined my database in database.yml file. Scaffold generated for me a model with controller and views. My table name is not as it must be for Rails(it is incorrect, not following conventions), i added set_table_name to my controller. But, when i am calling the index method, on my page i have only set of # symbols, but not a data from database. In my index.html.erb i have only generated code by scaffold. How can i print out my database data?
Have you generated a schema file from your existing database? If you run the command
rake db:schema:dump
and then re-generate your scaffold this should fix the problem.
Additionally you may wish to check out Dr Nic's Magic Model generator. This will generate models for all of your existing tables and attempt to guess the relationships. This will probably not work if your table naming is not understandable by rails.
UPDATE
I do not generally use the default scaffold however I have tested this myself and it appears that if you skip the migration and do not pass any column name/type pairs then the scaffold generator will not create anything in the template to render the columns.
You have two choices here either
Pass in the column name pairs as well as skip-migration or
Download Ryan Bates Nifty Scaffold generator which will create the scaffold with the column names even if you specify --skip-migration

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