# Ecto
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Ecto is a domain specific language for writing queries and interacting with databases in Elixir. Here is an example:
```elixir
# In your config/config.exs file
config :my_app, Sample.Repo,
adapter: Ecto.Adapters.Postgres,
database: "ecto_simple",
username: "postgres",
password: "postgres"
# In your application code
defmodule Sample.Repo do
use Ecto.Repo,
otp_app: :my_app
end
defmodule Sample.Weather do
use Ecto.Model
schema "weather" do
field :city # Defaults to type :string
field :temp_lo, :integer
field :temp_hi, :integer
field :prcp, :float, default: 0.0
end
end
defmodule Sample.App do
import Ecto.Query
alias Sample.Weather
alias Sample.Repo
def sample_query do
query = from w in Weather,
where: w.prcp > 0 or is_nil(w.prcp),
select: w
Repo.all(query)
end
end
```
See the [online documentation](http://hexdocs.pm/ecto) or [run the sample application](https://github.com/elixir-lang/ecto/tree/master/examples/simple) for more information.
## Usage
You need to add both Ecto and the database adapter as a dependency to your `mix.exs` file. The supported databases and their adapters are:
Database | Ecto Adapter | Dependency
:---------------------- | :--------------------- | :-------------------
PostgreSQL | Ecto.Adapters.Postgres | [postgrex][postgrex]
MySQL | Ecto.Adapters.MySQL | [mariaex][mariaex]
MSSQL | Tds.Ecto | [tds_ecto][tds_ecto]
SQLite3 | Sqlite.Ecto | [sqlite_ecto][sqlite_ecto]
[postgrex]: http://github.com/ericmj/postgrex
[mariaex]: http://github.com/xerions/mariaex
[tds_ecto]: https://github.com/livehelpnow/tds_ecto
[sqlite_ecto]: https://github.com/jazzyb/sqlite_ecto
For example, if you want to use PostgreSQL, add to your `mix.exs` file:
```elixir
defp deps do
[{:postgrex, ">= 0.0.0"},
{:ecto, "~> 0.9.0"}]
end
```
and update your applications list to include both projects:
```elixir
def application do
[applications: [:postgrex, :ecto]]
end
```
Then run `mix deps.get` in your shell to fetch the dependencies. If you want to use another database, just choose the proper dependency from the table above.
Finally, in the repository configuration, you will need to specify the `adapter:` respective to the chosen dependency. For PostgreSQL it is:
```elixir
config :my_app, Repo,
adapter: Ecto.Adapters.Postgres,
...
```
We are currently looking for contributions to add support for other SQL databases and folks interested in exploring non-relational databases too.
## Important links
* [Documentation](http://hexdocs.pm/ecto)
* [Mailing list](https://groups.google.com/forum/#!forum/elixir-ecto)
* [Examples](https://github.com/elixir-lang/ecto/tree/master/examples)
## Contributing
Ecto is on the bleeding edge of Elixir so the latest master build is most likely needed, see [Elixir's README](https://github.com/elixir-lang/elixir) on how to build from source.
To contribute you need to compile Ecto from source and test it:
```
$ git clone https://github.com/elixir-lang/ecto.git
$ cd ecto
$ mix deps.get
$ mix test
```
Besides the unit tests above, it is recommended to run the adapter integration tests too:
```
# Run only PostgreSQL tests
MIX_ENV=pg mix test
# Run all tests (unit and all adapters/pools)
mix test.all
```
## License
Copyright 2012 Plataformatec
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.