hkalexling / mg Goto Github PK

Hi

after_up and after_down don't seem to be executed when calling migrate. My puts statements there did not show up.

Hello,

Using Tags annotation with Posgres causes this SQL error:

STATEMENT:  PRAGMA user_version
ERROR:  syntax error at or near "PRAGMA" at character 1

Caused by https://github.com/hkalexling/mg/blob/master/src/mg/migration.cr#L83
Because PRAGMA is SQLite specific.

  @[MG::Tags("db1")]
  class CreateTables < MG::Base

When I remove Tags, the migrations are ok but the error is always here.
What is the use of Tags annotation?

Hello,

Thanks for this useful shards. The fact of managing migrations in Crystal code instead of raw SQL files allows some possibilities (available with migration libs in other languages, but non-existent in Crystal).

Unless I am mistaken, MG only allows to do actions before the migration and at the end of all migrations of course (after mg.migrate).

In the idea to be able to program actions during migrations, it would be interesting to have (optional) lifecycle methods in each class.

Example:

def up : String
   puts "before up.  Actually it's already possible"

  <<-SQL
    # SQL statements....
  SQL
end

def up_done
  puts "after up is done"
end

def down : String
   puts "before down.  Actually it's already possible"

  <<-SQL
    # SQL statements....
  SQL
end

def down_done
  puts "after down is done"
end

This can be useful to perform data conversions (due to a new DB structure by example), clean cache, ... Example for migrating entries linked by foreign keys, useful for the next migration.

Just a suggestion, this can be implemented by adding empty methods (example: up_done and down_done) in MG::Base. Then call them after exec query

What do you think?

Also, I have another question by the way. Is it an occasional shard (no particular need for you) or are you planning to maintain it for a long time?

This (curious) question because I want to add MG here https://github.com/Nicolab/crystal-dbx/blob/master/guide/migration.md (DBX docs) as well as use it by default in a framework that I will release soon 🙂

Hi

I have 2 sqlite3 databases - can this tool support migrating each of them? when I tried it gets confused saying duplicate versions found.