Product Perfect

Elixir Ecto is a database wrapper and query generator for the Elixir programming language, specifically designed to work efficiently with relational databases. Developed by Plataformatec and introduced in 2012, it provides a robust way of handling data access (source: GitHub). The software's main features include schema definitions, migrations support, and efficient data manipulation through its DSL (Domain Specific Language). It encourages good security practices by preventing common mistakes like SQL injection attacks. Its versatility makes it an indispensable tool for developers working with Elixir-based applications.

Ask the right questions secure the right Elixir Ecto talent among an increasingly shrinking pool of talent.

First 20 minutes

General Elixir Ecto app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in Elixir Ecto application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

What is the purpose of Elixir Ecto?

Elixir Ecto is a database wrapper and query generator that allows Elixir developers to interact with databases in a more efficient and reliable way. It provides a DSL for writing queries and handling data.

How would you define a schema in Ecto?

In Ecto, a schema is defined using the 'schema' keyword followed by the name of the database table. The fields of the table are then defined within a 'do' block, specifying the field name and type.

What are changesets in Elixir Ecto?

Changesets in Elixir Ecto are a way to filter, cast, validate, and define constraints when manipulating structs. They provide a way to track and validate changes before they are applied to the database.

How would you use Ecto to perform a simple query?

To perform a simple query in Ecto, you would use the 'from' function in combination with the 'Repo.all' function. For example, 'from(p in Post, where: p.published == true) |> Repo.all()' would return all published posts.

Describe the difference between 'preload' and 'join' in Ecto.

'preload' and 'join' are both used to load associated data in Ecto. However, 'preload' loads the data in separate queries, while 'join' loads the data in a single query. 'preload' is generally easier to use, while 'join' can be more efficient for complex queries.

The hiring guide has been successfully sent to your email address.

Oops! Something went wrong while submitting the form.

What you’re looking for early on

Does the candidate have a solid understanding of Elixir and Ecto?

Can the applicant demonstrate experience with building and managing databases using Elixir Ecto?

Has the candidate shown an understanding of OTP, the framework upon which Elixir is built?

Is the candidate able to solve problems and debug issues in Elixir and Ecto?

Next 20 minutes

Specific Elixir Ecto development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

What is the role of Ecto.Repo in Elixir Ecto?

Ecto.Repo is a repository that represents the application's database. It is used to perform all database operations, such as queries, inserts, updates, and deletes.

How would you handle database migrations in Ecto?

Database migrations in Ecto are handled using the 'mix ecto.migrate' command. This command runs all pending migrations. Migrations are defined in separate files in the 'priv/repo/migrations' directory.

What are the main components of Ecto and their roles?

The main components of Ecto are Ecto.Schema, Ecto.Changeset, and Ecto.Repo. Ecto.Schema is used to map database tables to Elixir structs. Ecto.Changeset is used to filter, cast, validate, and define constraints when manipulating structs. Ecto.Repo is used to perform all database operations.

How would you use Ecto to perform a complex query with multiple conditions?

To perform a complex query with multiple conditions in Ecto, you would use the 'from' function in combination with the 'where' function. For example, 'from(p in Post, where: p.published == true, where: p.views > 1000) |> Repo.all()' would return all published posts with more than 1000 views.

Describe the difference between 'Ecto.Query' and 'Ecto.Multi'.

'Ecto.Query' is used to write database queries, while 'Ecto.Multi' is used to perform multiple database operations in a single transaction. If any operation in the 'Ecto.Multi' fails, all operations are rolled back.

The hiring guide has been successfully sent to your email address.

Oops! Something went wrong while submitting the form.

At this point, a skilled Elixir Ecto engineer should demonstrate strong problem-solving abilities, proficiency in Elixir Ecto programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with Elixir Ecto.

What does this simple Elixir Ecto code do?
defmodule Repo.Migrations.CreateUsers do
  use Ecto.Migration

  def change do
    create table(:users) do
      add :name, :string
      add :email, :string
    end
  end
end
This Elixir Ecto code creates a new database migration that, when run, will create a new 'users' table with 'name' and 'email' fields, both of which are strings.
What does the following Elixir Ecto code do?
defmodule MyApp.User do
  use Ecto.Schema
  import Ecto.Changeset

  schema "users" do
    field :name, :string
    field :email, :string

    timestamps()
  end

  def changeset(user, attrs) do
    user
    |> cast(attrs, [:name, :email])
    |> validate_required([:name, :email])
  end
end
This Elixir Ecto code defines a 'User' schema that maps to the 'users' table in the database. It also defines a changeset function that is used to cast and validate changes before they are applied to the database.
What will be the output of the following Elixir Ecto code?
Repo.all(from u in User, select: u.name)
This Elixir Ecto code will return a list of all user names from the 'User' schema.
What does the following Elixir Ecto code do?
Repo.transaction(fn ->
  Repo.insert!(%User{name: "John", email: "john@example.com"})
  Repo.insert!(%User{name: "Jane", email: "jane@example.com"})
end)
This Elixir Ecto code creates a transaction that inserts two new users into the 'User' schema. If either insert fails, the entire transaction will be rolled back.

Wrap-up questions

Final candidate for Elixir Ecto Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle Elixir Ecto application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

What is the purpose of 'Ecto.Adapters.SQL' in Elixir Ecto?

'Ecto.Adapters.SQL' is used to interact with SQL databases. It provides functions for executing raw SQL queries and transactions.

How would you handle associations in Ecto?

Associations in Ecto are handled using the 'has_many', 'has_one', and 'belongs_to' functions in the schema definition. These functions define the relationship between different schemas.

What are the different types of associations in Ecto and how do they work?

The different types of associations in Ecto are 'has_many', 'has_one', and 'belongs_to'. 'has_many' and 'has_one' are used when a schema has one or many associated records. 'belongs_to' is used when a schema belongs to another schema.

Elixir Ecto application related

Product Perfect's Elixir Ecto development capabilities

Beyond hiring for your Elixir Ecto engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in Elixir Ecto projects, and can engage in multiple capacities.

Elixir Ecto Consultive assessments

Elixir Ecto Application Conversion Assessment Elixir Ecto Application Integration Assessment Elixir Ecto Data & Database Integration Assessment

Custom Elixir Ecto development projects

Custom Elixir Ecto App Conversion Elixir Ecto Custom App Development Process App UI Design for Elixir Ecto Facelifts

Hiring guide for Elixir Ecto Engineers

Elixir Ecto Developer Hiring Guide

What you’re looking for early on

The ideal back-end app developer

What you’re looking to see on the Elixir Ecto engineer at this point.

Elixir Ecto Consultive assessments

Custom Elixir Ecto development projects