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Dm adapter RubyConf.TW

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Dm adapter RubyConf.TW

  1. 1. Custom DataMapper Adapters By Josh Moore ( )
  2. 2. About Me• Josh Moore• Optimis Dev• github.com/joshsmoore• twitter.com/codingforrent• www.codingforrent.com• joshsmoore@gmail.com
  3. 3. DataMapper seams to be losing popularity why talk about it?
  4. 4. I enjoy non standard things...
  5. 5. It still has featuresActiveRecord/ActiveModel does not...
  6. 6. Try something new...
  7. 7. 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
  8. 8. Terms term meaningResource A model field A property on a modelRepository DataMapper term for the storage engine
  9. 9. Preamblerequire dm-core Just do itmodule DataMapper Just do it module Adapters class TestAdapter < AbstractAdapter ... end Just do it const_added(:TestAdapter) endend
  10. 10. Symbol Hashdef initialize(name, options)end
  11. 11. def initialize(name, options) Just do it superend
  12. 12. def initialize(name, options) superend
  13. 13. Connect to yourdef initialize(name, options) adapter super @conn = Mongo::Connection.new( options[:host], options[:port]) @adapter = @conn[options[:database]]end
  14. 14. 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
  15. 15. 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
  16. 16. 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
  17. 17. Array of Resourcesdef create(resources)end Return number of resources created
  18. 18. 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
  19. 19. 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
  20. 20. • 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"}
  21. 21. 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
  22. 22. 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
  23. 23. DataMapper::Querydef read(query)end Return a Array of Hashes key: field name value: unmarshed value {field_name => value}
  24. 24. def read(query) conditions = parse_query_conditions(query) @adapter[query.model.storage_name].find( conditions)end
  25. 25. Query Structure DataMapper::Query #conditions Operation #operands Set Operation Condition Array #subject Field Association
  26. 26. Query Structure DataMapper::Query #conditions Operation #operands Set Operation Condition Array #subject Field Association:conditions => ["updated_at > ?", Time.now]
  27. 27. Query Structure DataMapper::Query #conditions Operation #operands Set Operation Condition Array #subject Field Association :conditions => ["updated_at > ?", Time.now]:conditions => {:updated_at => {"$gte" => Time.now}}
  28. 28. Query Structure DataMapper::Query #conditions Operation #operands Set Operation Condition Hash Array #subject Field Association :conditions => ["updated_at > ?", Time.now]:conditions => {:updated_at => {"$gte" => Time.now}}
  29. 29. DataMapper::Querydef parse_query_conditions(query) mongo_conditions = {} Return a hash mongo_conditions
  30. 30. 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
  31. 31. 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
  32. 32. 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
  33. 33. 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
  34. 34. Post.all(:comments => {:body => hi})comments = Comment.all(:body => hi)post_ids = comments.collect { |c| c.post_id }Post.all(:id => post_ids)
  35. 35. 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] = {"$in" => condition.value.collect {|r| r.send(ck)}} else...
  36. 36. conditions.operands.each do |condition| ... case condition.class.to_s when ...InclusionComparison if condition.subject.instance_of?DataMapper::Associations::OneToMany::Relationship pk = condition.subject.parent_key.first.field ck = condition.subject.child_key.first.name mongo_conditions[pk] = {"$in" => condition.value.collect {|r| r.send(ck)}} else...
  37. 37. 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] = {"$in" => condition.value.collect {|r| r.send(ck)}} elseArray of properties * property - subclass of DataMapper::Property... * ex Coment#post_id
  38. 38. conditions.operands.each do |condition| ... case condition.class.to_s when ...InclusionComparison if condition.subject.instance_of?DataMapper::Associations::OneToMany::Relationship Array of resources pk = condition.subject.parent_key.first.field * [#<Comment..>, #<Comment..>,...] ck = condition.subject.child_key.first.name mongo_conditions[pk] = {"$in" => condition.value.collect {|r| r.send(ck)}} else...
  39. 39. 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] = {"$in" => condition.value.collect {|r| r.send(ck)}} else...
  40. 40. conditions.operands.each do |condition| ... case condition.class.to_s when ...InclusionComparison if condition.subject.instance_of?DataMapper::Associations::OneToMany::Relationship pk = condition.subject.parent_key.first.field ck = condition.subject.child_key.first.name mongo_conditions[pk] = {"$in" => condition.value.collect {|r| r.send(ck)}} else...
  41. 41. Operation• DataMapper::Query::Conditions::AndOperation• DataMapper::Query::Conditions::OrOperation• DataMapper::Query::Conditions::NotOperation
  42. 42. 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
  43. 43. What is not covered• Nested Operands
  44. 44. 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
  45. 45. def delete(resources) conditions = parse_query_conditions(resources.query) record_count = read(resources.query).count @adapter[resources.storage_name].remove(conditions) record_countend
  46. 46. 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)
  47. 47. 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
  48. 48. def update(changes, resources) conditions = parse_query_conditions(resources.query) @adapter[resources.storage_name].update(conditions, {"$set" => attributes_as_fields(changes)}, {:multi => true}) read(resources.query).countend
  49. 49. Unmarshaled hash of changes {<DataMapper::Property::String(title)> => "hasdf"} DataMapper::Collectiondef update(changes, resources) conditions = parse_query_conditions(resources.query) @adapter[resources.storage_name].update(conditions, {"$set" => attributes_as_fields(changes)}, {:multi => true}) read(resources.query).countend Number of resources updated (int)
  50. 50. 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
  51. 51. Be Kind log• DataMapper.logger
  52. 52. You can stop now end

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