Hocto

Easily query your PostgreSQL data with Ecto && Elixir.

👻 Setting up database

Rename example.config . exs (config folder) to config.exs and fill out the strings with your db informations.

import Config # <- don't delete this :: required.

# feel free to rename it to your own project name
config :hocto, ecto_repos: [Hocto.Repo]
config :hocto, Hocto.Repo,
  database: "", # localhost
  username: "", # postgres
  password: "", # either empty or <your password>
  hostname: ""  # localhost (if dev mode)

😝 Commands

Database basics

$ mix ecto.create

• [CLI]: The database for <> has been created.

Migration

$ mix ecto.gen.migration <some name>

priv/repo/migrations should be created (empty by default)

After writing schemas/migrations:

$ mix ecto.migrate

###> Queries After our data is saved, lets run some queries within the CLI.

$ iex -S mix
iex> person = %Hocto.Person{}
__meta__: #Ecto.Schema.Metadata<:built, "people">,
  first_name: nil,
  id: nil,
  last_name: nil,
  pin: nil
}

Our values are set to nil currently. We can set values on these fields by generating a new struct.

person = %Hocto.Person{pin: 445}
%Hocto.Person{
  __meta__: #Ecto.Schema.Metadata<:built, "people">,
  first_name: nil,
  id: nil,
  last_name: nil,
  pin: 445
}

This would work too (same thing but different syntax):

person = %{person | pin: 445}.

We can now retrive values with the following syntax

person.pin => 445.

New data (insert)

iex> person = %Hocto.Person{}
iex> Hocto.Repo.insert(person)

[debug] QUERY OK db=1.5ms decode=0.8ms queue=0.8ms idle=10.7ms
INSERT INTO "people" VALUES (DEFAULT) RETURNING "id" []
{:ok,
 %Hocto.Person{
   __meta__: #Ecto.Schema.Metadata<:loaded, "people">,
   first_name: nil,
   id: 1,
   last_name: nil,
   pin: nil
 }}

Awesome! 🎉

Let's go one step deeper and use pattern matching.

iex> {:ok, person} = Hocto.Repo.insert person

Nice, it's a cool && powerful syntax feature that elixir offers.

More (test) data

$ iex -S mix
iex> people = [
  %Friends.Person{first_name: "Koni", last_name: "Konrad", pin: 445},
  %Friends.Person{first_name: "Alex", last_name: "Alexander", pin: 667},
]
Enum.each(people, fn (person) -> Hocto.Repo.insert(person) end)

The result is going to be:

INSERT INTO "people" ("first_name","last_name","pin") VALUES ($1,$2,$3) RETURNING "id" ["Koni", "Konrad", 445]

12:24:52.279 [debug] QUERY OK db=1.2ms queue=0.7ms idle=718.4ms
INSERT INTO "people" ("first_name","last_name","pin") VALUES ($1,$2,$3) RETURNING "id" ["Alex", "Alexander", 667]
:ok

Fetching records

iex> Hocto.Person |> Ecto.Query.first
#Ecto.Query<from p0 in Hocto.Person, order_by: [asc: p0.id], limit: 1>

the same syntax would be

require Ecto.Query
Ecto.Query.from p in Hocto.Person, order_by: [asc: p.id], limit: 1

to execute that, we could do

Hocto.Person |> Ecto.Query.first |> Hocto.Repo.one

Result:

SELECT p0."id", p0."first_name", p0."last_name", p0."pin" FROM "people" AS p0 
ORDER BY p0."id" LIMIT 1 []
%Hocto.Person{
  __meta__: #Ecto.Schema.Metadata<:loaded, "people">,
  first_name: "Koni",
  id: 1,
  last_name: "Konrad",
  pin: 445
}