## Hi ## I have 6 simple and fundamental Problem in RoR migration and although I googled it and read many article about it and research it for a week , I didn''t understand it. please help me for these problems : ---------- 1 - When I create a model (for example "rails generate model Football_League") , I see in db/migration a "create_football_leagues.rb" . I want know what is the rules of RoR for changing the name that I gave to my migration ? ( My migration''s name was FootballLeague and ruby cretaed "create_football_leagues.rb") ---------- 2 - What is the rules of naming ruby for creating a class in that file ? ( Ruby created a "CreateFootballLeague" class in "create_football_leagues.rb") ---------- 3 - After I use rake db:migrate , although I had 3 migration, I just see such a image in cmd : ( I attached this image ) and I didn''t any migration for another 3 migrations whereas sometimes ago when I run a migration with rake db:migrate, all my migrations are migrated. ---------- 4 - After I type rake db:migrate and after that Rake execute "create_football_leagues.rb" I go to mysql and I saw a table with "schema_migrations" name. and in that table there are some versions of my migrations. now I want to know what is the application of such a table ? ---------- 5 - In http://guides.rubyonrails.org I read that if we want to change the primary key of a table from default id to our own field we must use :primary_key option but I didn''t understand how can I use it .If someone can give an example for this subject. ---------- 6 - What is the difference between this 2 commands : 1 - "rails generate migration footabll" 2 - rails generate model football. I knew that with "rails generate model football" we must some extra file in app/model but I don''t understand function of those files. My friend please help me to solve these fundamental problems . special thanks . Attachments: http://www.ruby-forum.com/attachment/6895/1.JPG -- Posted via http://www.ruby-forum.com/. -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
Peter Vandenabeele
2012-Jan-10 17:07 UTC
Re: 6 fundamental migration problems for beginners
On Tue, Jan 10, 2012 at 5:41 PM, amir e. <lists-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org> wrote:> ## Hi ## > I have 6 simple and fundamental Problem in RoR migration and although I > googled it and read many article about it and research it for a week , I > didn''t understand it. please help me for these problems : > > ---------- > > 1 - When I create a model (for example "rails generate model > Football_League") , I see in db/migration a "create_football_leagues.rb" > . I want know what is the rules of RoR for changing the name that I gave > to my migration ? ( My migration''s name was FootballLeague and ruby > cretaed "create_football_leagues.rb") > > > ---------- > > > 2 - What is the rules of naming ruby for creating a class in that file ? > ( Ruby created a "CreateFootballLeague" class in > "create_football_leagues.rb") > > > ---------- > > > 3 - After I use rake db:migrate , although I had 3 migration, I just see > such a image in cmd : ( I attached this image ) > and I didn''t any migration for another 3 migrations whereas sometimes > ago when I run a migration with rake db:migrate, all my migrations are > migrated. > > > ---------- > > > 4 - After I type rake db:migrate and after that Rake execute > "create_football_leagues.rb" I go to mysql and I saw a table with > "schema_migrations" name. and in that table there are some versions of > my migrations. now I want to know what is the application of such a > table ? > > > ---------- > > > 5 - In http://guides.rubyonrails.org I read that if we want to change > the primary key of a table from default id to our own field we must use > :primary_key option but I didn''t understand how can I use it .If someone > can give an example for this subject. > > > ---------- > > 6 - What is the difference between this 2 commands : 1 - "rails generate > migration footabll" 2 - rails generate model football. I knew that > with "rails generate model football" we must some extra file in > app/model but I don''t understand function of those files. > > > My friend please help me to solve these fundamental problems . special > thanks . > > Attachments: > http://www.ruby-forum.com/attachment/6895/1.JPG > >Study "Rails Guides" http://guides.rubyonrails.org/ * Getting started * Migrations * check for "generators" * ... HTH, Peter -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
On 10 January 2012 16:41, amir e. <lists-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org> wrote:> ## Hi ## > I have 6 simple and fundamental Problem in RoR migration and although I > googled it and read many article about it and research it for a week , I > didn''t understand it. please help me for these problems :Rather than answer the questions in detail I suggest that you work right through a good tutorial such as railstutorial.org, which is free to use online, then many such questions will be answered. Also look at the Rails Guides. Make sure that you have installed the version of rails that matches the tutorial you are using. I will say, though, do not change the primary key from id unless you absolutely must do this, to cope with a legacy database. Otherwise you will make life difficult. Colin> > ---------- > > 1 - When I create a model (for example "rails generate model > Football_League") , I see in db/migration a "create_football_leagues.rb" > . I want know what is the rules of RoR for changing the name that I gave > to my migration ? ( My migration''s name was FootballLeague and ruby > cretaed "create_football_leagues.rb") > > > ---------- > > > 2 - What is the rules of naming ruby for creating a class in that file ? > ( Ruby created a "CreateFootballLeague" class in > "create_football_leagues.rb") > > > ---------- > > > 3 - After I use rake db:migrate , although I had 3 migration, I just see > such a image in cmd : ( I attached this image ) > and I didn''t any migration for another 3 migrations whereas sometimes > ago when I run a migration with rake db:migrate, all my migrations are > migrated. > > > ---------- > > > 4 - After I type rake db:migrate and after that Rake execute > "create_football_leagues.rb" I go to mysql and I saw a table with > "schema_migrations" name. and in that table there are some versions of > my migrations. now I want to know what is the application of such a > table ? > > > ---------- > > > 5 - In http://guides.rubyonrails.org I read that if we want to change > the primary key of a table from default id to our own field we must use > :primary_key option but I didn''t understand how can I use it .If someone > can give an example for this subject. > > > ---------- > > 6 - What is the difference between this 2 commands : 1 - "rails generate > migration footabll" 2 - rails generate model football. I knew that > with "rails generate model football" we must some extra file in > app/model but I don''t understand function of those files. > > > My friend please help me to solve these fundamental problems . special > thanks . > > Attachments: > http://www.ruby-forum.com/attachment/6895/1.JPG > > > -- > Posted via http://www.ruby-forum.com/. > > -- > You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. > To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org > To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. > For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en. >-- gplus.to/clanlaw -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
>> > Study "Rails Guides" http://guides.rubyonrails.org/ > * Getting started > * Migrations > * check for "generators" > * ... > > HTH, > > PeterI study it , and if I didn''t understand. -- Posted via http://www.ruby-forum.com/. -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
On 01/10/2012 09:41 AM, amir e. wrote:> ## Hi ## > I have 6 simple and fundamental Problem in RoR migration and although I > googled it and read many article about it and research it for a week , I > didn''t understand it. please help me for these problems : > > ---------- > > 1 - When I create a model (for example "rails generate model > Football_League") , I see in db/migration a "create_football_leagues.rb" > . I want know what is the rules of RoR for changing the name that I gave > to my migration ? ( My migration''s name was FootballLeague and ruby > cretaed "create_football_leagues.rb") >The name of the migration is only of passing interest. What it is named has very little to do with what it does. The whole idea of the migrations is to create/delete database tables and indexes and to add/remove columns to existing tables and sometimes to insert small amounts of initial data into tables (not recommended). The important thing in the migrations is the names of the tables and the names of the columns. The name of the migration is just so you recall what that migration was all about.> ---------- > > > 2 - What is the rules of naming ruby for creating a class in that file ? > ( Ruby created a "CreateFootballLeague" class in > "create_football_leagues.rb") >As in the migration name, the name of the class that is in that file is of little interest. It is only used when you run a migration and really has nothing to do with what the migration really does. The class is bound to the name of the file by some rules that are not really very interesting. Just go with it and don''t worry about it.> ---------- > > > 3 - After I use rake db:migrate , although I had 3 migration, I just see > such a image in cmd : ( I attached this image ) > and I didn''t any migration for another 3 migrations whereas sometimes > ago when I run a migration with rake db:migrate, all my migrations are > migrated. > > > ---------- > > > 4 - After I type rake db:migrate and after that Rake execute > "create_football_leagues.rb" I go to mysql and I saw a table with > "schema_migrations" name. and in that table there are some versions of > my migrations. now I want to know what is the application of such a > table ? > >The schema_migrations table is used to keep track of which migrations have been run. In 3 above all of the previously defined migrations have run so the only one that will be run is the new one. If you change a migration file which has already been run it will not be rerun. Only the migrations on a whole are tracked. If you want to run all of the migrations you can just ''rake db:drop db:create db:migrate''. Of course you will loose any data that is in the database.> ---------- > > > 5 - In http://guides.rubyonrails.org I read that if we want to change > the primary key of a table from default id to our own field we must use > :primary_key option but I didn''t understand how can I use it .If someone > can give an example for this subject. > >Don''t do it. Rails works best and most easily if you go with the flow.> ---------- > > 6 - What is the difference between this 2 commands : 1 - "rails generate > migration footabll" 2 - rails generate model football. I knew that > with "rails generate model football" we must some extra file in > app/model but I don''t understand function of those files. > >You need to read the tutorials on models. The migration generates the database tables. The model files define relations among the different Active Record classes that are formed from those columns. At a minimum a model file is required for each table (that you want to use with Active Record). The file will look like:[code]class Column < ActiveRecord::Base end<[/code]The relations are descirbed in the model files. Norm> My friend please help me to solve these fundamental problems . special > thanks . > > Attachments: > http://www.ruby-forum.com/attachment/6895/1.JPG > >-- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.
Peter Vandenabeele
2012-Jan-10 22:29 UTC
Re: Re: 6 fundamental migration problems for beginners
On Tue, Jan 10, 2012 at 6:21 PM, amir e. <lists-fsXkhYbjdPsEEoCn2XhGlw@public.gmane.org> wrote:> >> > > Study "Rails Guides" http://guides.rubyonrails.org/ > > * Getting started > > * Migrations > > * check for "generators" > > * ... > > > > HTH, > > > > Peter > > I study it , and if I didn''t understand. >OK, great. A good way to get better responses on a mailing is to mention e.g. "what did you read", "what did you try", "what was the outcome", "why do you think that is not correct" etc. E.g. from this guide: http://catb.org/~esr/faqs/smart-questions.html " Before You Ask Before asking a technical question by e-mail, or in a newsgroup, or on a website chat board, do the following: Try to find an answer by searching the archives of the forum you plan to post to. Try to find an answer by searching the Web. Try to find an answer by reading the manual. Try to find an answer by reading a FAQ. Try to find an answer by inspection or experimentation. Try to find an answer by asking a skilled friend. If you''re a programmer, try to find an answer by reading the source code. When you ask your question, display the fact that you have done these things first; this will help establish that you''re not being a lazy sponge and wasting people''s time. Better yet, display what you have learned from doing these things. We like answering questions for people who have demonstrated they can learn from the answers. " Hope This helps and welcome :-) Peter -- Peter Vandenabeele http://twitter.com/peter_v http://rails.vandenabeele.com -- You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to rubyonrails-talk-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en.