SQL com Arel no Rails

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Transcript

1. SQL com Arel no Rails
2. $ whoami Desenvolvedor Backend na Codeminer42 Github, Twitter, Linkedin: @luchiago
3. Active Record Arel Introdução ao SQL Agenda Exemplo 01 02 03 04
4. Introdução ao SQL 01
6. O que é o SQL? • Structured Query Language (ou, Linguagem de Consulta Estruturada) • Inspirada na Álgebra Relacional • Desenvolvida pela IBM • NoSQL
7. Exemplos Leitura Escrita Atualização Deleção SELECT * FROM Customers; INSERT INTO Customers (CustomerName, ContactName, Address, City, PostalCode, Country) VALUES ('Cardinal','Tom B. Erichsen','Skagen 21','Stavanger','4006','Norway'); UPDATE Customers SET ContactName='Alfred Schmidt', City='Frankfurt' WHERE CustomerID=1; DELETE FROM Customers WHERE CustomerName='Alfreds Futterkiste';
8. Active Record 02
9. Active Record • Padrão de projeto • Patterns of Enterprise Application Architecture, por Martin Fowler • ORM • MVC
10. Exemplos SQL Rails ActiveRecord SELECT 1 AS one FROM "users" WHERE "users"."email" = $1 LIMIT $2 [["email", "kinginthenorth@example.com"], ["LIMIT", 1]] INSERT INTO "users" ("email", "password", "name", "password_confirmation") VALUES ($1, $2, $3, $4) RETURNING "id" [["email", "kinginthenorth@example.com"], ["password", "123456"], ["name", "João das Neves"], ["password_confirmation", "123456"]] User.create(name: 'João das Neves', email: 'kinginthenorth@example.com', password: '123456', password_confirmation: '123456')
12. Arel 03
13. Arel • A principio, uma framework de framework • Álgebra relacional para Ruby • Gerenciamento da SQL AST • Mantida pela organização Rails
15. Exemplo 04
16. User.arel_table => #<Arel::Table:0x0000556cca67ed28 @name="users", @type_caster=#<ActiveRecord::TypeCaster::Map:0x0000556cca67eda0 @types=User (call 'User.connection' to establish a connection)>, @table_alias=nil>
17. User.where("age > ? OR (name = ? AND age < ?)", age1, name1, age2) User.where(column[:age].gt(age1).or(column[:name].eq(name1).and(column[: age2].lt(age2)))) private def column(symbol) User.arel_table[symbol] end
18. Dúvidas?
19. Obrigado!