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Diffstat (limited to 'activerecord/lib/active_record/model_schema.rb')
| -rw-r--r-- | activerecord/lib/active_record/model_schema.rb | 303 |
1 files changed, 303 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb new file mode 100644 index 0000000000..c1a8583119 --- /dev/null +++ b/activerecord/lib/active_record/model_schema.rb @@ -0,0 +1,303 @@ +require 'active_support/concern' +require 'active_support/core_ext/class/attribute_accessors' + +module ActiveRecord + module ModelSchema + extend ActiveSupport::Concern + + included do + ## + # :singleton-method: + # Accessor for the prefix type that will be prepended to every primary key column name. + # The options are :table_name and :table_name_with_underscore. If the first is specified, + # the Product class will look for "productid" instead of "id" as the primary column. If the + # latter is specified, the Product class will look for "product_id" instead of "id". Remember + # that this is a global setting for all Active Records. + config_attribute :primary_key_prefix_type, :global => true + + ## + # :singleton-method: + # Accessor for the name of the prefix string to prepend to every table name. So if set + # to "basecamp_", all table names will be named like "basecamp_projects", "basecamp_people", + # etc. This is a convenient way of creating a namespace for tables in a shared database. + # By default, the prefix is the empty string. + # + # If you are organising your models within modules you can add a prefix to the models within + # a namespace by defining a singleton method in the parent module called table_name_prefix which + # returns your chosen prefix. + config_attribute :table_name_prefix + self.table_name_prefix = "" + + ## + # :singleton-method: + # Works like +table_name_prefix+, but appends instead of prepends (set to "_basecamp" gives "projects_basecamp", + # "people_basecamp"). By default, the suffix is the empty string. + config_attribute :table_name_suffix + self.table_name_suffix = "" + + ## + # :singleton-method: + # Indicates whether table names should be the pluralized versions of the corresponding class names. + # If true, the default table name for a Product class will be +products+. If false, it would just be +product+. + # See table_name for the full rules on table/class naming. This is true, by default. + config_attribute :pluralize_table_names + self.pluralize_table_names = true + end + + module ClassMethods + # Guesses the table name (in forced lower-case) based on the name of the class in the + # inheritance hierarchy descending directly from ActiveRecord::Base. So if the hierarchy + # looks like: Reply < Message < ActiveRecord::Base, then Message is used + # to guess the table name even when called on Reply. The rules used to do the guess + # are handled by the Inflector class in Active Support, which knows almost all common + # English inflections. You can add new inflections in config/initializers/inflections.rb. + # + # Nested classes are given table names prefixed by the singular form of + # the parent's table name. Enclosing modules are not considered. + # + # ==== Examples + # + # class Invoice < ActiveRecord::Base + # end + # + # file class table_name + # invoice.rb Invoice invoices + # + # class Invoice < ActiveRecord::Base + # class Lineitem < ActiveRecord::Base + # end + # end + # + # file class table_name + # invoice.rb Invoice::Lineitem invoice_lineitems + # + # module Invoice + # class Lineitem < ActiveRecord::Base + # end + # end + # + # file class table_name + # invoice/lineitem.rb Invoice::Lineitem lineitems + # + # Additionally, the class-level +table_name_prefix+ is prepended and the + # +table_name_suffix+ is appended. So if you have "myapp_" as a prefix, + # the table name guess for an Invoice class becomes "myapp_invoices". + # Invoice::Lineitem becomes "myapp_invoice_lineitems". + # + # You can also set your own table name explicitly: + # + # class Mouse < ActiveRecord::Base + # self.table_name = "mice" + # end + # + # Alternatively, you can override the table_name method to define your + # own computation. (Possibly using <tt>super</tt> to manipulate the default + # table name.) Example: + # + # class Post < ActiveRecord::Base + # def self.table_name + # "special_" + super + # end + # end + # Post.table_name # => "special_posts" + def table_name + reset_table_name unless defined?(@table_name) + @table_name + end + + # Sets the table name explicitly. Example: + # + # class Project < ActiveRecord::Base + # self.table_name = "project" + # end + # + # You can also just define your own <tt>self.table_name</tt> method; see + # the documentation for ActiveRecord::Base#table_name. + def table_name=(value) + @original_table_name = @table_name if defined?(@table_name) + @table_name = value + @quoted_table_name = nil + @arel_table = nil + @relation = Relation.new(self, arel_table) + end + + # Returns a quoted version of the table name, used to construct SQL statements. + def quoted_table_name + @quoted_table_name ||= connection.quote_table_name(table_name) + end + + # Computes the table name, (re)sets it internally, and returns it. + def reset_table_name #:nodoc: + if active_record_super.abstract_class? + self.table_name = active_record_super.table_name || compute_table_name + elsif abstract_class? + self.table_name = active_record_super == Base ? nil : active_record_super.table_name + else + self.table_name = compute_table_name + end + end + + def full_table_name_prefix #:nodoc: + (parents.detect{ |p| p.respond_to?(:table_name_prefix) } || self).table_name_prefix + end + + # The name of the column containing the object's class when Single Table Inheritance is used + def inheritance_column + (@inheritance_column ||= nil) || active_record_super.inheritance_column + end + + # Sets the value of inheritance_column + def inheritance_column=(value) + @original_inheritance_column = inheritance_column + @inheritance_column = value.to_s + end + + def sequence_name + if base_class == self + @sequence_name ||= reset_sequence_name + else + (@sequence_name ||= nil) || base_class.sequence_name + end + end + + def reset_sequence_name #:nodoc: + self.sequence_name = connection.default_sequence_name(table_name, primary_key) + end + + # Sets the name of the sequence to use when generating ids to the given + # value, or (if the value is nil or false) to the value returned by the + # given block. This is required for Oracle and is useful for any + # database which relies on sequences for primary key generation. + # + # If a sequence name is not explicitly set when using Oracle or Firebird, + # it will default to the commonly used pattern of: #{table_name}_seq + # + # If a sequence name is not explicitly set when using PostgreSQL, it + # will discover the sequence corresponding to your primary key for you. + # + # class Project < ActiveRecord::Base + # self.sequence_name = "projectseq" # default would have been "project_seq" + # end + def sequence_name=(value) + @original_sequence_name = @sequence_name if defined?(@sequence_name) + @sequence_name = value.to_s + end + + # Indicates whether the table associated with this class exists + def table_exists? + connection.schema_cache.table_exists?(table_name) + end + + # Returns an array of column objects for the table associated with this class. + def columns + @columns ||= connection.schema_cache.columns[table_name].map do |col| + col = col.dup + col.primary = (col.name == primary_key) + col + end + end + + # Returns a hash of column objects for the table associated with this class. + def columns_hash + @columns_hash ||= Hash[columns.map { |c| [c.name, c] }] + end + + # Returns a hash where the keys are column names and the values are + # default values when instantiating the AR object for this table. + def column_defaults + @column_defaults ||= Hash[columns.map { |c| [c.name, c.default] }] + end + + # Returns an array of column names as strings. + def column_names + @column_names ||= columns.map { |column| column.name } + end + + # Returns an array of column objects where the primary id, all columns ending in "_id" or "_count", + # and columns used for single table inheritance have been removed. + def content_columns + @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column } + end + + # Returns a hash of all the methods added to query each of the columns in the table with the name of the method as the key + # and true as the value. This makes it possible to do O(1) lookups in respond_to? to check if a given method for attribute + # is available. + def column_methods_hash #:nodoc: + @dynamic_methods_hash ||= column_names.inject(Hash.new(false)) do |methods, attr| + attr_name = attr.to_s + methods[attr.to_sym] = attr_name + methods["#{attr}=".to_sym] = attr_name + methods["#{attr}?".to_sym] = attr_name + methods["#{attr}_before_type_cast".to_sym] = attr_name + methods + end + end + + # Resets all the cached information about columns, which will cause them + # to be reloaded on the next request. + # + # The most common usage pattern for this method is probably in a migration, + # when just after creating a table you want to populate it with some default + # values, eg: + # + # class CreateJobLevels < ActiveRecord::Migration + # def up + # create_table :job_levels do |t| + # t.integer :id + # t.string :name + # + # t.timestamps + # end + # + # JobLevel.reset_column_information + # %w{assistant executive manager director}.each do |type| + # JobLevel.create(:name => type) + # end + # end + # + # def down + # drop_table :job_levels + # end + # end + def reset_column_information + connection.clear_cache! + undefine_attribute_methods + connection.schema_cache.clear_table_cache!(table_name) if table_exists? + + @column_names = @content_columns = @column_defaults = @columns = @columns_hash = nil + @dynamic_methods_hash = @inheritance_column = nil + @arel_engine = @relation = nil + end + + def clear_cache! # :nodoc: + connection.schema_cache.clear! + end + + private + + # Guesses the table name, but does not decorate it with prefix and suffix information. + def undecorated_table_name(class_name = base_class.name) + table_name = class_name.to_s.demodulize.underscore + table_name = table_name.pluralize if pluralize_table_names + table_name + end + + # Computes and returns a table name according to default conventions. + def compute_table_name + base = base_class + if self == base + # Nested classes are prefixed with singular parent table name. + if parent < ActiveRecord::Model && !parent.abstract_class? + contained = parent.table_name + contained = contained.singularize if parent.pluralize_table_names + contained += '_' + end + "#{full_table_name_prefix}#{contained}#{undecorated_table_name(name)}#{table_name_suffix}" + else + # STI subclasses always use their superclass' table. + base.table_name + end + end + end + end +end |