class Cql::Schema

Reference < Object

The Schema class represents a database schema.

This class provides methods to build and manage a database schema, including creating tables, executing SQL statements, and generating queries.

Example Creating a new schema

schema = Cql::Schema.define(:northwind, "sqlite3://db.sqlite3") do
  table :users do
    primary :id, Int64, auto_increment: true
    column :name, String
    column :email, String
  end
end

Example Executing a SQL statement

schema.exec("CREATE TABLE products (id INTEGER PRIMARY KEY, name TEXT)")

Example Creating a new query

query = schema.query

The Schema class represents a database schema.

Constants

Log

::Log.for(self)

Constructors

def new(name : Symbol, uri : String, adapter : Adapter = Adapter::Sqlite, version : String = "1.0")

Initializes a new schema.

• @param name [Symbol] the name of the schema

• @param uri [String] the URI of the database

• @param adapter [Adapter] the database adapter (default: Adapter::Sqlite)

• @param version [String] the version of the schema (default: "1.0")

Example Initializing a new schema

schema = Cql::Schema.new(:northwind, "sqlite3://db.sqlite3")

Class Methods

def define(name : Symbol, uri : String, adapter : Adapter = Adapter::Sqlite, version : String = "1.0", &)

Builds a new schema.

• @param name [Symbol] the name of the schema

• @param uri [String] the URI of the database

• @param adapter [Adapter] the database adapter (default: Adapter::Sqlite)

• @param version [String] the version of the schema (default: "1.0")

• @yield [Schema] the schema being built

• @return [Schema] the built schema

Example

schema = Cql::Schema.define(:northwind, "sqlite3://db.sqlite3") do |s|
  s.create_table :users do
    primary :id, Int64, auto_increment: true
    column :name, String
    column :email, String
  end
end

Instance Methods

def adapter

• @return [Adapter] the database adapter (default: Adapter::Sqlite)

def alter(table_name : Symbol, &)

Alter a table in the schema.

• @param table_name [Symbol] the name of the table

• @yield [AlterTable] the table being altered Example

schema.alter(:users) do |t|
  t.add_column :age, Int32
end

Example

schema.alter(:users) do |t|
  t.drop_column :age
end

def db

• @return [DB::Connection] the database connection

def delete

Creates a new delete query for the schema.

• @return [Delete] the new delete query Example

delete = schema.delete

def exec(sql : String)

Executes a SQL statement.

• @param sql [String] the SQL statement to execute

Example

schema.exec("CREATE TABLE users (id INTEGER PRIMARY KEY, name TEXT)")

def gen

• @return [Expression::Generator] the expression generator

def insert

Creates a new insert query for the schema.

• @return [Insert] the new insert query Example

insert = schema.insert

def migrator

Creates a new migrator for the schema.

• @return [Migrator] the new migrator Example

migrator = schema.migrator

def name

• @return [Symbol] the name of the schema

def query

Creates a new query for the schema.

• @return [Query] the new query

Example

query = schema.query

def table(name : Symbol, as as_name = nil, &)

Creates a new table in the schema.

• @param name [Symbol] the name of the table

• @param as_name [Symbol] the alias of the table

• @yield [Table] the table being created

• @return [Table] the created table Example

schema.create_table :users do
  primary :id, Int64, auto_increment: true
  column :name, String
  column :email, String
end

def tables

• @return [Hash(Symbol, Table)] the tables in the schema

def update

Creates a new update query for the schema.

• @return [Update] the new update query Example

update = schema.update

def uri

• @return [String] the URI of the database

def version

• @return [String] the version of the schema

Macros

macro method_missing(call)