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A lot of time when i run rake db:migrate i get an error because the table user or foor or bar exist.
I try to check the existence of table, but that didn't work and i dont know why .
I use rails 3.2.2
class AddDeviseToUsers < ActiveRecord::Migration
#def self.table_exists?(users)
# ActiveRecord::Base.connection.tables.include?(users)
#end
if !table_exists?("users")
def change
create_table(:users) do |t|
## Database authenticatable
t.string :email, :null => false, :default => ""
t.string :encrypted_password, :null => false, :default => ""
end
end
end
You can check the existence of a table with the following command. This question has already been posted and answered here.
ActiveRecord::Base.connection.table_exists? 'users'
However, your code contains errors. You cannot define a method inside an if block with the syntax you're using. Put the block inside your method, instead.
def change
if !table_exists?("users")
# ...
end
end
Also, you should not be getting this kind of errors often, as you state. Migrations are applied sequentially. Creating your users table in a separate migration before adding Devise to it would take care of that problem. If you run into this problem while migrating an existing project from scratch, consider using rake db:schema:load instead.
In your command terminal type in
sqlite3 db/development.sqlite3
then you can search through your database by SQL command. Use .tables to list all tables in the database and you can see if yours is missing or not.
You can also just look at your schema file to see if the migration worked. The table along with all of it's attributes will be listed there.
You should never have multiple migrations that both try to create the same table. You also should not experience errors like this if you're working with rails migrations correctly.
The way rails migrations work is that every time you run rake db:migrate, for every migration file that runs successfully, it stores the number part of the migration file 123456789_create_users_table.rb (123456789 in this case) in a table in your db called schema_migrations. This way if a migration has already been run, it will never get run again.
It doesn't sound like you're working with rails migrations correctly. I suggest reading this thoroughly: http://guides.rubyonrails.org/migrations.html
Related
I have the following migrations
Problem is that rake db:migrate is not executing the first migration and no users table is created.
What could be the reason for this?
What could be the reason for this?
Main reason is probably that you've already ran the migration - or perhaps later migrations - and Rails therefore does not think it needs to run it.
A good way to see if this is the case is to open your db/schema.rb file:
You'll see the latest migration your schema is running. If this supersedes the one you're trying to invoke, it will not run.
--
Fixes
You could generate a new migration, and copy the code over:
$ rails g migration AddUsers2
You'd then add the following:
#db/migrate/_____.rb
class AddUsers2 < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :name
t.timestamps
end
end
end
Alternatively, you could wipe your DB and start again. This can be achieved using rake schema:load. THIS WILL WIPE ALL DATA AND START AGAIN
I just started to learn Ruby on Rails. And when I used the rails to do the test, an error occurred as:
UserTest#test_the_truth:
ActiveRecord::StatementInvalid: Mysql2::Error: Table 'eula_test.destroys' doesn't exist: SHOW FULL FIELDS FROM destroys
I don't know what is eula_test.destroys and how should I solve this problem.
check your migration files. on db/migrate.rb and db/shema.rb you can check out if you have that table.
Seems no-one has been able to answer this, but best guess based on the error you are getting it looks like you need a join table because you most likely have a "has_and_belongs_to_many" directive in both your models eula.rb and test.rb
So you need to create a migration: rails g migration CreateEulaTest
then edit the migration to include an index that tells the db to look in eula_test table for the data to join with.
you need edit your migration with the following:
def up
create_table :eula_test, :id => false do |t|
t.integer :eula_id
t.integer :test_id
end
add_index(:eula_test, [:eula_id, :test_id]
end
def down
drop_table :eula_test
end
end
Note: this table does not require it's own ID hence the :id => false
Also, the add_index portion are your foreign keys between the 2 models that allows the database to know that you are going through the table to establish your directive, such as create and destroy etc.
run rails db:migrate for rails 5 or greater, rake db:migrate <5
You may need to check your models to ensure you have the correct has_to_and_belongs_to_many settings.
It is likely you missed this part of the tutorial. Some tutorials don't explain why things are done, they just show you the code and let you figure it out.
rails db:reset should fix it :)
Running through Michael Hartl's well known Rails tutorial, hit this snag.
I have this in a migration file, created by rails generate model etc:
class CreateUsers < ActiveRecord::Migration
def change
create_table :users do |t|
t.string :name
t.string :email
t.timestamps
end
end
end
Later, I added this second migration file:
class AddIndexToUsersEmail < ActiveRecord::Migration
def change
add_index :users, :email, unique: true
end
end
To try and update the database to include the new one, I followed the instructions and ran rake db:migrate, but this gives me an error telling me I'm trying to create a table that already exists, which is to say I'm clearly missing something.
Am I...supposed to delete the first migration? That wouldn't make any sense. What to do?
(These are the only files under db/migrate)
if you realy want to see what migrations have been ran into the database, you can inspect your app database, there is a table called schema_migrations, in there you can see the unique id of each migration as a row for example is your migration is called: 20130402190449_add_flagand_table.rb, you should see the number 20130402190449 as a row of that table, hope i gave you some guidance
What you can do is rollback couple of migration and re-run.
You can rollback migration like this
#rake db:rollback STEP=2
and then run
#rake db:migrate
Hope it should work
My issues was my 2nd to last migration ran and it was trying to rerun that migration again after i added a new migration.
I ended up just commenting out the code inside the one it was trying to rerun, and then ran rake db:migrate then uncommented the migration code.
This way the schema does not break and it fixes whatever bug occurred.
I'm getting an error:
SQLite3::SQLException: no such column: ideas.list_id:
SELECT "ideas".* FROM "ideas"
WHERE "ideas"."list_id" = 2
But I added
t.integer :list_id
to my db migration file:
class CreateIdeas < ActiveRecord::Migration
def change
create_table :ideas do |t|
t.string :name
t.text :description
t.string :picture
t.timestamps
end
add_foreign_key :ideas, :lists
end
end
which gave me this:
class CreateIdeas < ActiveRecord::Migration
def change
create_table :ideas do |t|
t.string :name
t.text :description
t.string :picture
t.integer :list_id
t.timestamps
end
add_foreign_key :ideas, :lists
end
end
and then I typed
rake db:migrate
Any idea why I would be getting an error saying there's no column? I'm still new to RoRs. Do I have to add a column some other way?
Thanks
As Speransky suggested, you should never modify old migration files. Rather you should create a new migration that adds the desired column. For instance, in this case you would run the following command in your app to create the new migration:
rails generate migration AddListIdColumnToIdeas list_id:integer
And Rails would generate the migration file automatically and the only thing left to do is run rake db:migrate.
If you insist on modifying the old migration file, you can add the column as you did and run the following:
rake db:drop
rake db:create
rake db:migrate
Which will destroy your current database, create a new one and run all the migrations (which will include your new column).
If you want to add a new column to an exist database, you should use rails generate migration. So you can try rails generate migration add_list_id_to_ideas list_id:integer and then use rake db:migrate to commit this change.
You should not add new rows to old migrations. Migration is a step of building database. And number of last executed migration is stored in schema, and it will not be run or redone if you use will use rake db:migrate. If you run the migration with creating the table before, then you should create new migration where you may use add_column method.
migration file name has the datetime encoded in its name so rails run this migration one and do not run it again unless you do a rollback
and here come the magic of migration to build you db with small steps so no need to update a migration after run rake db:migrate , you should make a new migration to do the change you want to your db schema
and remember to
remove the added line form the old migration file as it might raise errors if you decided to rollback this migration
Rails 4.0 easy way to add single or multiple column
https://gist.github.com/pyk/8569812
You can also do this ..
rails g migration add_column_to_users list_id:string
then rake db:migrate
also add :list_id attribute in your user controller ;
for more detail check out http://guides.rubyonrails.org/active_record_migrations.html
If you already have files in your migrate folder, you could just add column you want there(just type the code), delete development.sqlite or whatever represents your db file, and run rake db:migrate.
It will then create a new sqlite file with new column in table, and you can check it in schema.rb
So, basically, everything you did seems good, except you didn't delete your database file.
Doing this seems the easiest for me, all though you will lose all the files in your database. If you're just testing and developing Rails app, this works.
Can anyone comment if there is something wrong with this approach, besides what i wrote?
Edit: I actually found an answer about that here
Editing Existing Rails Migrations is a good idea?
I can't seem to find an option or anything that allows me to skip migrations.
I know what you're thinking: "you should never have to do that..."
I need to skip a migration that makes changes to specific user records that don't exist in my development database. I don't want to change the migration because it is not part of the source I am supposed to be working with. Is there a way to skip a migration or skip failed migrations?
Thanks in advance!
I think you should fix the offending migrations to be less fragile, I'd guess that a couple of if statements and perhaps a rescue would be sufficient.
But, if fixing the migrations really isn't an option, you can fake it in various ways. First of all, you could just comment out the migration methods, run rake db:migrate, and then uncomment (or revert) the offending migration.
You can also fake it inside the database but this sort of chicanery is not recommended unless you know what you're doing and you don't mind manually patching things up when you (inevitably) make a mistake. There is a table in your database called schema_migrations that has a single varchar(255) column called version; this table is used by db:migrate to keep track of which migrations have been applied. All you need to do is INSERT the appropriate version value and rake db:migrate will think that the migration has been done. Find the offending migration file:
db/migrate/99999999999999_XXXX.rb
then go into your database and say:
insert into schema_migrations (version) values ('99999999999999');
where 99999999999999 is, of course, the number from the migration's file name. Then running rake db:migrate should skip that migration.
I'd go with the second option before the third, I'm only including the "hack schema_versions" option for completeness.
I had an issue where I had a migration to add a table that already existed, so in my case I had to skip this migration as well, because I was getting the error
SQLite3::SQLException: table "posts" already exists: CREATE TABLE "posts"
I simply commented out the content of the create table method, ran the migration, and then uncommented it out. It's kind of a manual way to get around it, but it worked. See below:
class CreatePosts < ActiveRecord::Migration
def change
# create_table :posts do |t|
# t.string :title
# t.text :message
# t.string :attachment
# t.integer :user_id
# t.boolean :comment
# t.integer :phase_id
# t.timestamps
# end
end
end
This is a good way to do it for one-off errors.
db:migrate:up VERSION=my_version
This will run one specific migration's "up" actions. (There is also the opposite if you need it, just replace "up" with "down".) So this way you can either run the future migration that makes the older one (that you need to skip) work, or just run each migration ahead of it selectively.
I also believe that you can redo migrations this way:
rake db:migrate:redo VERSION=my_version
I have not tried that method personally, so YMMV.
If you have to do that, your app's migrations are messed up!
Inserts all missing migrations:
def insert(xxx)
ActiveRecord::Base.connection.execute("insert into schema_migrations (version) values (#{xxx})") rescue nil
end
files = Dir.glob("db/migrate/*")
files.collect { |f| f.split("/").last.split("_").first }.map { |n| insert(n) }
To skip all pending migrations, run this in your terminal:
echo "a = [" $(rails db:migrate:status | grep "down" | grep -o '[0-9]\{1,\}' | tr '\n' ', ') "];def insert(b);ActiveRecord::Base.connection.execute(\"insert into schema_migrations (version) values (#{b})\") rescue nil;end;a.map { |b| insert(b)}" | xclip
(For macOS use pbcopy instead of xclip)
Then CTRL-V the result inside rails console:
a = [ 20180927120600,20180927120700 ];def insert(b);ActiveRecord::Base.connection.execute("insert into schema_migrations (version) values (#{b})") rescue nil;end;a.map { |b| insert(b)}
And hit ENTER.
You can change the list of migrations you want to skip by removing them from array a before executing the line.
Instead of skip the migration you could make your migration smart, adding some IF to it, so you can check "specific users"
sometimes, it is necessary to re-fill schema_migrations table with definitely correct migrations...
ONLY FOR THIS PURPOSE i have created this method
def self.insert_missing_migrations(stop_migration=nil)
files = Dir.glob("db/migrate/*")
timestamps = files.collect{|f| f.split("/").last.split("_").first}
only_n_first_migrations = timestamps.split(stop_migration).first
only_n_first_migrations.each do |version|
sql = "insert into `schema_migrations` (`version`) values (#{version})"
ActiveRecord::Base.connection.execute(sql) rescue nil
end
end
you can copy-paste it into any model you want and use it from console
YourModel.insert_missing_migrations("xxxxxxxxxxxxxx")
(or somehow else)
where "xxxxxxxxxxxxxx" - is timestamp of migration before which you want to stop insertion (you can leave it empty)
!!! use it only if you absolutely understand what result will you get !!!