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https://github.com/cogini/ecto_extract_migrations
Elixir library to generate Ecto migrations from a PostgreSQL schema SQL file. Uses NimbleParsec and macro-style code generation.
https://github.com/cogini/ecto_extract_migrations
ecto elixir-library postgresql sql
Last synced: 10 days ago
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Elixir library to generate Ecto migrations from a PostgreSQL schema SQL file. Uses NimbleParsec and macro-style code generation.
- Host: GitHub
- URL: https://github.com/cogini/ecto_extract_migrations
- Owner: cogini
- License: apache-2.0
- Created: 2020-05-28T03:36:31.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2021-01-22T08:52:09.000Z (almost 4 years ago)
- Last Synced: 2024-09-17T20:07:38.734Z (about 2 months ago)
- Topics: ecto, elixir-library, postgresql, sql
- Language: Elixir
- Homepage:
- Size: 322 KB
- Stars: 17
- Watchers: 5
- Forks: 3
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- License: LICENSE
Awesome Lists containing this project
README
# ecto_extract_migrations
[](https://hex.pm/packages/ecto_extract_migrations)
[](https://hexdocs.pm/ecto_extract_migrations/)
[](https://hex.pm/packages/ecto_extract_migrations)
[](https://hex.pm/packages/ecto_extract_migrations)
[](https://github.com/cogini/ecto_extract_migrations/commits/master)
Mix task to generate Ecto migrations from a Postgres schema SQL file.
This lets you take an existing project and move it into Elixir
with a proper development workflow.
## Usage
1. Generate a schema-only dump of the database to SQL:
```shell
pg_dump --schema-only --no-owner postgres://dbuser:dbpassword@localhost/dbname > dbname.schema.sql
```
2. Generate migrations from the SQL file:
```shell
mix ecto.extract.migrations --sql-file dbname.schema.sql
```
or, from outside the target project:
```shell
mix ecto.extract.migrations --sql-file dbname.schema.sql --repo "MyProject.Repo" --migrations-path ../myproject/priv/repo/migrations
```
3. Create a test database, run migrations to create the schema, then
export it and verify that it matches the original database:
```shell
createuser --encrypted --pwprompt dbuser
dropdb dbname_migrations
createdb -Odbuser -Eutf8 dbname_migrations
mix ecto.migrate --log-sql
pg_dump --schema-only --no-owner postgres://dbuser@localhost/dbname_migrations > dbname_migrations.sql
cat dbname.schema.sql | grep -v -E '^--|^$' > old.sql
cat dbname_migrations.sql | grep -v -E '^--|^$' > new.sql
diff -wu old.sql new.sql
```
## Details
This was written to migrate a legacy database with hundreds of tables and
objects.
The parser uses [NimbleParsec](https://github.com/dashbitco/nimble_parsec), and
is based on the SQL grammar, so it is precise (unlike regex) and reasonably
complete. It doesn't support every esoteric option, just what we needed, but
that was quite a lot. Patches are welcome.
Supports:
* `ALTER SEQUENCE`
* `ALTER TABLE`
* `CREATE EXTENSION`
* `CREATE FUNCTION`
* `CREATE INDEX`
* `CREATE SCHEMA`
* `CREATE SEQUENCE`
* `CREATE TABLE`
* `CREATE TRIGGER`
* `CREATE TYPE`
* `CREATE VIEW`
## Installation
Add `ecto_extract_migrations` to your list of dependencies in `mix.exs`:
```elixir
def deps do
[
{:ecto_extract_migrations, "~> 0.1.0"}
]
end
```
## Resources
Here are some useful resources for NimbleParsec:
* https://stefan.lapers.be/posts/elixir-writing-an-expression-parser-with-nimble-parsec/
* https://github.com/slapers/ex_sel
## Alternatives
* [ecto_generator](https://github.com/pmarreck/ecto_generator) generates Ecto schemas by querying
the database [information schema](https://www.postgresql.org/docs/13/information-schema.html)
* [ex_abnf](https://github.com/marcelog/ex_abnf) generates a parser based on an
[ABNF grammar](https://en.wikipedia.org/wiki/Augmented_Backus%E2%80%93Naur_form).