Dm adapter RubyConf.TW

Custom DataMapper Adapters By Josh Moore ( )

About Me• Josh Moore• Optimis Dev• github.com/joshsmoore• twitter.com/codingforrent• www.codingforrent.com• joshsmoore@gmail.com

DataMapper seams to be losing popularity why talk about it?

I enjoy non standard things...

It still has featuresActiveRecord/ActiveModel does not...

Try something new...

Examplesclass Comment class Post include include DataMapper::Resource DataMapper::Resource property :id, Serial property :id, Serial property :body, String property :title, String belongs_to :post has n, :commentsend end

Terms term meaningResource A model field A property on a modelRepository DataMapper term for the storage engine

Preamblerequire dm-core Just do itmodule DataMapper Just do it module Adapters class TestAdapter < AbstractAdapter ... end Just do it const_added(:TestAdapter) endend

Symbol Hashdef initialize(name, options)end

def initialize(name, options) Just do it superend

def initialize(name, options) superend

Connect to yourdef initialize(name, options) adapter super @conn = Mongo::Connection.new( options[:host], options[:port]) @adapter = @conn[options[:database]]end

def initialize(name, options) super @conn = Mongo::Connection.new( Sub class of: DataMapper::Property options[:host], options[:port]) @adapter = @conn[options[:database]] @field_naming_convention = Proc.new do |field| field.model.storage_name + _ + field.name.to_s end Return a Stringend

def initialize(name, options) super @conn = Mongo::Connection.new( options[:host], options[:port]) @adapter = @conn[options[:database]] @field_naming_convention = Proc.new do |field| field.model.storage_name String (class.to_s) + _ + field.name.to_s end @resource_naming_convention = Proc.new do |resource| resource.downcase end Return a Stringend

def initialize(name, options) super @conn = Mongo::Connection.new( options[:host], options[:port]) @adapter = @conn[options[:database]] @field_naming_convention = Proc.new do |field| field.model.storage_name + _ + field.name.to_s end @resource_naming_convention = Proc.new do |resource| resource.downcase endend

Array of Resourcesdef create(resources)end Return number of resources created

def create(resources) resources.collect do |resource| initialize_serial(resource, @adapter[resource.class.storage_name].find.count) fields = attributes_as_fields( resource.attributes(:property)) @adapter[resource.class.storage_name].insert(fields) end.sizeend

• Accepts: Hash • Key: Sub class of: DataMapper::Property • Value: non marshaled data • example: {<DataMapper::Property::String(title)> => "hasdf"}def create(resources) resources.collect do |resource| initialize_serial(resource, @adapter[resource.class.storage_name].find.count) fields = attributes_as_fields( resource.attributes(:property)) @adapter[resource.class.storage_name].insert(fields) end.size • Return: Hash • Key: @field_naming_convention resultend • Value: Marshaled data • Only values that are set •Example: {"post_title" => "hasdf"}

def create(resources) resources.collect do |resource| initialize_serial(resource, @adapter[resource.class.storage_name].find.count) fields = attributes_as_fields( resource.attributes(:property)) @adapter[resource.class.storage_name].insert(fields) end.sizeend

def create(resources) resources.collect do |resource| initialize_serial(resource, @adapter[resource.class.storage_name].find.count) fields = attributes_as_fields( resource.attributes(:property)) @adapter[resource.class.storage_name].insert(fields) end.sizeend Unless an Exception is raised the resource will be considered saved

DataMapper::Querydef read(query)end Return a Array of Hashes key: field name value: unmarshed value {field_name => value}

def read(query) conditions = parse_query_conditions(query) @adapter[query.model.storage_name].find( conditions)end

Query Structure DataMapper::Query #conditions Operation #operands Set Operation Condition Array #subject Field Association

Query Structure DataMapper::Query #conditions Operation #operands Set Operation Condition Array #subject Field Association:conditions => ["updated_at > ?", Time.now]

Query Structure DataMapper::Query #conditions Operation #operands Set Operation Condition Array #subject Field Association :conditions => ["updated_at > ?", Time.now]:conditions => {:updated_at => {"$gte" => Time.now}}

Query Structure DataMapper::Query #conditions Operation #operands Set Operation Condition Hash Array #subject Field Association :conditions => ["updated_at > ?", Time.now]:conditions => {:updated_at => {"$gte" => Time.now}}

DataMapper::Querydef parse_query_conditions(query) mongo_conditions = {} Return a hash mongo_conditions

query.conditions.operands.each do |condition| def parse_query_conditions(query) mongo_conditions = {} case condition.class.to_s when DataMapper::Query::Conditions::GreaterThanComparison mongo_conditions[condition.subject.field] = { "$gt" => condition.value} when DataMapper::Query::Conditions::LessThanComparison mongo_conditions[condition.subject.field] = { "$lt" => condition.value} else mongo_conditions[condition.subject.field] = condition.value end mongo_conditionsend end

def parse_query_conditions(query) mongo_conditions = {} query.conditions.operands.each do |condition| case condition.class.to_s when DataMapper::Query::Conditions::GreaterThanComparison mongo_conditions[condition.subject.field] = { "$gt" => condition.value} when DataMapper::Query::Conditions::LessThanComparison mongo_conditions[condition.subject.field] = { "$lt" => condition.value} else mongo_conditions[condition.subject.field] = condition.value end end mongo_conditionsend

Post.all(:comments => {:body => hi})comments = Comment.all(:body => hi)post_ids = comments.collect { |c| c.post_id }Post.all(:id => post_ids)

conditions.operands.each do |condition| ... case condition.class.to_s when ...InclusionComparison if condition.subject.instance_of?DataMapper::Associations::OneToMany::Relationship pk = condition.subject.parent_key.first.field ck = condition.subject.child_key.first.name mongo_conditions[pk] = {"$in" => condition.value.collect {|r| r.send(ck)}} else...

conditions.operands.each do |condition| ... Array of properties case condition.class.to_s * property - subclass of DataMapper::Property * ex. Post#id when ...InclusionComparison if condition.subject.instance_of?DataMapper::Associations::OneToMany::Relationship pk = condition.subject.parent_key.first.field ck = condition.subject.child_key.first.name mongo_conditions[pk] = {"$in" => condition.value.collect {|r| r.send(ck)}} elseArray of properties * property - subclass of DataMapper::Property... * ex Coment#post_id

conditions.operands.each do |condition| ... case condition.class.to_s when ...InclusionComparison if condition.subject.instance_of?DataMapper::Associations::OneToMany::Relationship Array of resources pk = condition.subject.parent_key.first.field * [#<Comment..>, #<Comment..>,...] ck = condition.subject.child_key.first.name mongo_conditions[pk] = {"$in" => condition.value.collect {|r| r.send(ck)}} else...

conditions.operands.each do |condition| ... case condition.class.to_s when ...InclusionComparison if condition.subject.instance_of?DataMapper::Associations::OneToMany::Relationship pk = condition.subject.parent_key.first.field ck = condition.subject.child_key.first.name mongo_conditions[pk] = {"$in" => condition.value.collect {|r| r.send(ck)}} else...

Operation• DataMapper::Query::Conditions::AndOperation• DataMapper::Query::Conditions::OrOperation• DataMapper::Query::Conditions::NotOperation

Condition• DataMapper::Query::Conditions::EqualToComparison• DataMapper::Query::Conditions::InclusionComparison• DataMapper::Query::Conditions::RegexpComparison• DataMapper::Query::Conditions::LikeComparison• DataMapper::Query::Conditions::GreaterThanComparison• DataMapper::Query::Conditions::LessThanComparison• DataMapper::Query::Conditions::GreaterThanOrEqualToComparison• DataMapper::Query::Conditions::LessThanOrEqualToComparison

What is not covered• Nested Operands

If your backed does not have a query language A Array of Hashes key: field name value: unmarshed value [{field_name => value}]def read(query) query.filter_records(records)end

def delete(resources) conditions = parse_query_conditions(resources.query) record_count = read(resources.query).count @adapter[resources.storage_name].remove(conditions) record_countend

DataMapper::Collectiondef delete(resources) conditions = parse_query_conditions(resources.query) record_count = read(resources.query).count @adapter[resources.storage_name].remove(conditions) record_countend Number of resources deleted (int)

def delete(resources) conditions = parse_query_conditions(resources.query) record_count = read(resources.query).count @adapter[resources.storage_name].remove(conditions) record_countend Unless an Exception is raised the resource will be considered saved

def update(changes, resources) conditions = parse_query_conditions(resources.query) @adapter[resources.storage_name].update(conditions, {"$set" => attributes_as_fields(changes)}, {:multi => true}) read(resources.query).countend

Unmarshaled hash of changes {<DataMapper::Property::String(title)> => "hasdf"} DataMapper::Collectiondef update(changes, resources) conditions = parse_query_conditions(resources.query) @adapter[resources.storage_name].update(conditions, {"$set" => attributes_as_fields(changes)}, {:multi => true}) read(resources.query).countend Number of resources updated (int)

def update(changes, resources) conditions = parse_query_conditions(resources.query) @adapter[resources.storage_name].update(conditions, {"$set" => attributes_as_fields(changes)}, {:multi => true}) read(resources.query).countend Unless an Exception is raised the resource will be considered saved

Be Kind log• DataMapper.logger

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