Rails params explained

Question

Could anyone explain params in Rails controller  where they come from  and what they are referencing     def create      vote   Vote new params  vote       item   params  vote   item id      uid   params  vote   user id       extant   Vote find  last   conditions   gt    item id     AND user id       item  uid       last vote time    extant created at unless  extant blank      curr time   Time now   end   I would like to be able to read this code line-by-line and understand what s going on

User · Answer

As others have pointed out  params values can come from the query string of a GET request  or the form data of a POST request  but there s also a third place they can come from  The path of the URL   As you might know  Rails uses something called routes to direct requests to their corresponding controller actions  These routes may contain segments that are extracted from the URL and put into params  For example  if you have a route like this   match  products  id         Then a request to a URL like http   example com products 42 will set params  id  to 42

User · Answer

Params contains the following three groups of parameters    User supplied parameters  GET  http   domain com url param1 value1 amp param2 value2 will set params  param1  and params  param2   POST  e g  JSON  XML will automatically be parsed and stored in params  Note  By default  Rails duplicates the user supplied parameters and stores them in params  user  if in UsersController  can be changed with wrap parameters setting  Routing parameters  match   user  id  in routes rb will set params  id   Default parameters  params  controller  and params  action  is always available and contains the current controller and action

User · Answer

On the Rails side  params is a method that returns an ActionController  Parameters object   See https   stackoverflow com a 44070358 5462485

User · Answer

Basically  parameters are user specified data to rails application   When you post a form  you do it generally with POST request as opposed to GET request  You can think normal rails requests as GET requests  when you browse the site  if it helps   When you submit a form  the control is thrown back to the application  How do you get the values you have submitted to the form  params is how    About your code   vote   Vote new params  vote  creates new Vote to database using data of params  vote   Given your form user submitted was named under name  vote  all data of it is in this  vote field of the hash   Next two lines are used to get item and uid user has submitted to the form     extant   Vote find  last   conditions   gt    item id     AND user id       item  uid     finds newest  or last inserted  vote from database with conditions item id   item and user id   uid   Next lines takes last vote time and current time

User · Answer

The params come from the user s browser when they request the page   For an HTTP GET request  which is the most common  the params are encoded in the url   For example  if a user s browser requested  http   www example com  foo 1 amp boo octopus  then params  foo  would be  1  and params  boo  would be  octopus    In HTTP HTML  the params are really just a series of key-value pairs where the key and the value are strings  but Ruby on Rails has a special syntax for making the params be a hash with hashes inside   For example  if the user s browser requested  http   www example com  vote item id  1 amp vote user id  2  then params  vote  would be a hash  params  vote   item id  would be  1  and params  vote   user id  would be  2    The Ruby on Rails params are the equivalent of the   REQUEST array in PHP

[ruby-on-rails] Rails params explained?

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