Class: SqlcachedClient::Entity

Inherits:
Object
  • Object
show all
Extended by:
Arel, TreeVisitor
Defined in:
lib/sqlcached_client/entity.rb

Class Attribute Summary collapse

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Arel

build_arel

Methods included from TreeVisitor

visit_in_preorder

Constructor Details

#initialize(attributes) ⇒ Entity

Returns a new instance of Entity.

Parameters:

  • attributes (Hash) 


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# File 'lib/sqlcached_client/entity.rb', line 14

def initialize(attributes)
  @attributes = attributes
  define_readers(attributes.keys)
end

Class Attribute Details

.query_id ⇒ Object (readonly)

Returns the value of attribute query_id.



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# File 'lib/sqlcached_client/entity.rb', line 21

def query_id
  @query_id
end

Instance Attribute Details

#attributes ⇒ Object (readonly)

Returns the value of attribute attributes.



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# File 'lib/sqlcached_client/entity.rb', line 11

def attributes
  @attributes
end

Class Method Details

.association_names ⇒ Object 



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# File 'lib/sqlcached_client/entity.rb', line 181

def association_names
  registered_associations.map(&:accessor_name)
end

.build_query_tree ⇒ Object 



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# File 'lib/sqlcached_client/entity.rb', line 207

def build_query_tree
  # returns the subtrees (associated classes) of the given entity class
  get_associated_entities = -> (entity) {
    entity.registered_associations.map do |a|
      Module.const_get(a.class_name)
    end
  }

  # function to apply to each node while traversing the tree
  visit = -> (entity, parent, index) {
    entity.server.build_request_item(
      entity.query_id,
      entity.query,
      # query_params
      if parent
        Hash[
          parent.registered_associations[index].join_attributes.map do |j_attr|
            [ j_attr[0], {
              value: j_attr[1],
              type:
                if entity.join_constant_value?(j_attr[1])
                  'constant'
                else
                  'parent_attribute'
                end
            } ]
          end
        ]
      else
        nil
      end,
      entity.cache
    ).merge(associations: entity.association_names)
  }

  # builds the result of a visit step
  result_builder = -> (root, subtrees) {
    { root: root, subtrees: subtrees }
  }

  # traverse the tree
  visit_in_preorder(get_associated_entities, visit, result_builder)
end

.cache(seconds = nil) ⇒ Object

Configures the caching timing if a parameter is provided, otherwise returns the value set in the current class or in a superclass. Default value is true.



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# File 'lib/sqlcached_client/entity.rb', line 193

def cache(seconds = nil)
  if seconds.nil?
    @cache ||
      if superclass = ancestors[1..-1].detect { |a| a.respond_to?(:cache) }
        superclass.cache
      else
        true
      end
  else
    @cache = seconds
  end
end

.entity_name(value) ⇒ Object

Sets the name of this entity



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# File 'lib/sqlcached_client/entity.rb', line 24

def entity_name(value)
  @query_id = value
end

.has_many(accessor_name, options) ⇒ Object

Defines a ‘has_many’ relationship. Available options are

class_name

Specifies the class of the associated objects, if not given it’s inferred from the accessor_name (singularized + camelized).

where

Specifies how to fill the query template for the associated objects. It’s an hash where each key is a foreign parameter that will be set to the value provided. A special case occours when the value is a Symbol, in this case it represents the value of the attribute named as the symbol. For example, where: { id: :user_id } fills the parameter id of the foreign entity with the value of self.user_id.



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# File 'lib/sqlcached_client/entity.rb', line 114

def has_many(accessor_name, options)
  foreign_class_name =
    if options[:class_name].present?
      options[:class_name]
    else
      accessor_name.to_s.singularize.camelize
    end
  # the query to run to get the data
  association = -> (this, foreign_entity, join_attributes, dry_run) {
    foreign_entity.where(Hash[ join_attributes.map do |attr_names|
      attr_value =
        if this.join_constant_value?(attr_names[1])
          attr_names[1]
        else
          this.send(attr_names[1])
        end
      [ attr_names[0], attr_value ]
    end ], dry_run)
  }
  # get the attributes to define the foreign scope
  join_attributes = (options[:where] || []).to_a
  # memoize the associated resultset
  memoize_var = "@has_many_#{accessor_name}"
  # define the accessor method
  define_method(accessor_name) do |dry_run = false|
    # get the associated entity class
    foreign_entity = Module.const_get(foreign_class_name)
    if dry_run
      association.(self, foreign_entity, join_attributes, true)
    else
      instance_variable_get(memoize_var) ||
        instance_variable_set(memoize_var,
          association.(self, foreign_entity, join_attributes, false))
    end
  end
  # define the setter method
  define_method("#{accessor_name}=") do |array|
    # get the associated entity class
    foreign_entity = Module.const_get(foreign_class_name)
    instance_variable_set(memoize_var,
      Resultset.new(foreign_entity, array))
  end
  # save the newly created association
  register_association(OpenStruct.new({
    accessor_name: accessor_name.to_sym,
    class_name: foreign_class_name,
    join_attributes: join_attributes
  }))
end

.has_one(accessor_name, options) ⇒ Object

Defines a ‘has_one’ relationship. See ‘has_many’ for the available options



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# File 'lib/sqlcached_client/entity.rb', line 166

def has_one(accessor_name, options)
  plural_accessor_name = "s_#{accessor_name}".to_s.pluralize
  class_name = accessor_name.to_s.camelize
  has_many(plural_accessor_name, { class_name: class_name }.merge(options))
  define_method(accessor_name) do
    send(plural_accessor_name).first
  end
end

.is_an_association?(name) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sqlcached_client/entity.rb', line 186

def is_an_association?(name)
  association_names.include?(name.to_sym)
end

.join_constant_value?(value) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sqlcached_client/entity.rb', line 252

def join_constant_value?(value)
  !value.is_a?(Symbol)
end

.load_tree(root_conditions) ⇒ Object

Like ‘where’ but loads every associated entity recursively at any level,

with only one interaction with the server

Parameters:

  • root_conditions (Array) 


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# File 'lib/sqlcached_client/entity.rb', line 259

def load_tree(root_conditions)
  server.session do |server, session|
    Resultset.new(
      self,
      server.run_query(
        session,
        server.build_tree_request(build_query_tree, root_conditions)
      )
    )
  end
end

.query(*args, &block) ⇒ Object

Sets the query of this entity if a parameter is provided, otherwise returns the value previously set.



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# File 'lib/sqlcached_client/entity.rb', line 30

def query(*args, &block)
  if args.empty?
    @query
  else
    if args[0].is_a?(String)
      @query = args[0].strip
    else
      @query = build_arel(
        args.inject({}) do |acc, param|
          acc.merge(
            param.is_a?(Hash) ? param : Hash[ [[param, nil]] ]
          )
        end,
        block).to_sql
    end
  end
end

.registered_associations ⇒ Object 



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# File 'lib/sqlcached_client/entity.rb', line 176

def registered_associations
  @registered_associations || []
end

.server(config = nil) ⇒ Object

Configures the server of this entity if a parameter is provided, otherwise returns the server object previously set.



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# File 'lib/sqlcached_client/entity.rb', line 50

def server(config = nil)
  if config.nil?
    @server ||
      if superclass = ancestors[1..-1].detect { |a| a.respond_to?(:server) }
        superclass.server
      else
        nil
      end
  else
    @server =
      if config.is_a?(Hash)
        Server.new(config)
      else
        config
      end
  end
end

.server_session(&block) ⇒ Object

Gets a session from the server and yields the passed block



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# File 'lib/sqlcached_client/entity.rb', line 69

def server_session(&block)
  server.session(&block)
end

.where(params, dry_run = false) ⇒ Resultset

Runs the entity query with the provided parameters

Returns:



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# File 'lib/sqlcached_client/entity.rb', line 75

def where(params, dry_run = false)
  request =
    begin
      paramIterator = -> (parameter) {
        server.build_request_item(query_id, query, parameter, cache)
      }
      if params.is_a?(Array)
        params.map { |p| instance_exec(p, &paramIterator) }
      else
        instance_exec(params, &paramIterator)
      end
    end
  if dry_run
    request
  else
    data =
      server.session do |server, session|
        server.run_query(session, server.build_request(
          request.is_a?(Array) ? request : [request]
        ))
      end
    data.flatten!(1) if data.is_a?(Array)
    Resultset.new(self, data)
  end
end

Instance Method Details

#build_associations(max_depth = false) ⇒ Object 



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# File 'lib/sqlcached_client/entity.rb', line 330

def build_associations(max_depth = false)
  Resultset.new(self.class, [self]).build_associations(max_depth)
end

#define_readers(attr_names) ⇒ Object

Define the readers for the attribute names specified

Parameters:

  • attr_names (Array) 


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# File 'lib/sqlcached_client/entity.rb', line 281

def define_readers(attr_names)
  attr_names.each do |attr_name|
    if respond_to?(attr_name)
      if self.class.is_an_association?(attr_name)
        # lazy instantiate associated records
        association_writer = method("#{attr_name}=")
        association_reader = method(attr_name)
        define_singleton_method(attr_name) do
          association_writer.(attributes[attr_name])
          association_reader.()
        end
      else
        raise "Cannot define accessor: #{attr_name}"
      end
    else
      define_singleton_method(attr_name) do
        attributes[attr_name]
      end
    end
  end
end

#get_association_requests ⇒ Object 



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# File 'lib/sqlcached_client/entity.rb', line 309

def get_association_requests
  self.class.association_names.map do |a_name|
    send(a_name, true)
  end
end

#get_associations ⇒ Object 



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# File 'lib/sqlcached_client/entity.rb', line 323

def get_associations
  self.class.association_names.map do |a_name|
    send(a_name)
  end
end

#join_constant_value?(value) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sqlcached_client/entity.rb', line 304

def join_constant_value?(value)
  self.class.join_constant_value?(value)
end

#set_associations_data(associations_data) ⇒ Object 



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# File 'lib/sqlcached_client/entity.rb', line 316

def set_associations_data(associations_data)
  self.class.association_names.map.with_index do |a_name, i|
    send("#{a_name}=", associations_data[i])
  end
end

#to_h ⇒ Object 



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# File 'lib/sqlcached_client/entity.rb', line 335

def to_h
  attributes
end