Other frameworks had big mapping files (name in the Customer model maps to name in the customers table) that you had to tediously write out by hand, or pay money to buy a tool that would do it for you (and then edit it by hand). This looks like a ruby-fied version of your database schema. Well, if you want to make a change to your Rails app’s database, you use migrations.
These are a series of files, in the db/migrate folder, that have long version numbers (actually time-stamps) attached to them.
And, because everybody makes mistakes, it’s easy to rollback migrations with the .
The code and more detailed documentation are on Git Hub Seed migration emerged from our internal needs at Harry’s.
After we started working on it, we found those libraries that have similar yet different behavior.
Databases are very strict and often refuse to do things if they’re not comfortable with it.
Just as schema migrations apply incremental changes to your database, seed migrations apply incremental data updates.
A few examples of real world seed migrations: Applying those migrations will automatically update the seeds file with instructions to recreate all the objects.
) or by running a manually written one off script against your production database (yuk again! The Seed Migration gem solves these issues by allowing you to define .
At their core they are extremely similar to Rails’ built-in schema migrations.