Experimental Mongo support for ActiveRecord.
Here is an instructional video:
Created
February 27, 2011 00:34
-
-
Save tenderlove/845782 to your computer and use it in GitHub Desktop.
readme
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| module Arel | |
| module Visitors | |
| ### | |
| # The Identity visitor returns anything passed to the `accept` method. | |
| class Identity < Arel::Visitors::Visitor | |
| def initialize engine | |
| end | |
| def accept ast | |
| ast | |
| end | |
| end | |
| end | |
| end |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| module Arel | |
| module Visitors | |
| class Mongo < Arel::Visitors::Visitor | |
| attr_reader :db | |
| def initialize db | |
| @db = db | |
| end | |
| Query = Struct.new(:collection_name, :fields, :conditions) | |
| private | |
| def visit_Arel_Nodes_SelectStatement o | |
| o.cores.map { |c| visit_Arel_Nodes_SelectCore c }.map { |query| | |
| collection = db.collection query.collection_name | |
| fields = query.fields | |
| selector = Hash[query.conditions] | |
| opts = {} | |
| opts[:fields] = fields unless fields.empty? | |
| opts[:limit] = o.limit.expr.to_i if o.limit | |
| collection.find(selector, opts).to_a | |
| }.flatten | |
| end | |
| def visit_Arel_Nodes_SelectCore o | |
| fields = o.projections.map { |proj| visit(proj) }.compact | |
| conditions = o.wheres.map { |condition| visit(condition) }.flatten(1) | |
| Query.new(visit(o.source), fields, conditions) | |
| end | |
| def visit_Arel_Nodes_And o | |
| o.children.map { |child| visit child } | |
| end | |
| def visit_Arel_Nodes_Equality o | |
| [visit(o.left), visit(o.right)] | |
| end | |
| def visit_Arel_Attributes_Attribute o | |
| return if o.name == '*' | |
| o.name | |
| end | |
| def visit_Arel_Nodes_JoinSource o | |
| visit o.left | |
| end | |
| def visit_Arel_Table o | |
| o.name | |
| end | |
| def literal o; o; end | |
| alias :visit_String :literal | |
| alias :visit_Fixnum :literal | |
| end | |
| end | |
| end |
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| require 'active_record/connection_adapters/abstract_adapter' | |
| require 'arel/visitors/identity' | |
| require 'arel/visitors/mongo' | |
| # Ensure that to_sql returns the AST. | |
| Arel::Visitors::VISITORS['mongo'] = Arel::Visitors::Identity | |
| require 'mongo' | |
| module ActiveRecord | |
| class Base | |
| def self.mongo_connection(config) | |
| connection = Mongo::Connection.new | |
| ConnectionAdapters::MongoAdapter.new(connection, logger, config) | |
| end | |
| end | |
| module ConnectionAdapters | |
| class MongoAdapter < AbstractAdapter | |
| attr_reader :db | |
| def initialize connection, logger, config | |
| super(connection, logger) | |
| @config = config | |
| @db = connection.db config[:database] | |
| end | |
| ### | |
| # There is no concept of columns, so return an empty set. | |
| def columns(table_name, name = nil) | |
| [] | |
| end | |
| def table_exists? name | |
| true | |
| end | |
| def primary_key table | |
| "_id" | |
| end | |
| def select(ast, name = nil, binds = []) | |
| visitor = Arel::Visitors::Mongo.new db | |
| visitor.accept ast | |
| end | |
| end | |
| end | |
| end |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment