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ActiveRecord::ModelSchema::ClassMethods

Public Instance Methods

column_defaults() click to toggle source

Returns a hash where the keys are column names and the values are default values when instantiating the AR object for this table.

# File lib/active_record/model_schema.rb, line 242
def column_defaults
  @column_defaults ||= Hash[columns.map { |c| [c.name, c.default] }]
end
column_names() click to toggle source

Returns an array of column names as strings.

# File lib/active_record/model_schema.rb, line 247
def column_names
  @column_names ||= columns.map { |column| column.name }
end
columns() click to toggle source

Returns an array of column objects for the table associated with this class.

# File lib/active_record/model_schema.rb, line 227
def columns
  @columns ||= connection.schema_cache.columns[table_name].map do |col|
    col = col.dup
    col.primary = (col.name == primary_key)
    col
  end
end
columns_hash() click to toggle source

Returns a hash of column objects for the table associated with this class.

# File lib/active_record/model_schema.rb, line 236
def columns_hash
  @columns_hash ||= Hash[columns.map { |c| [c.name, c] }]
end
content_columns() click to toggle source

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.

# File lib/active_record/model_schema.rb, line 253
def content_columns
  @content_columns ||= columns.reject { |c| c.primary || c.name =~ /(_id|_count)$/ || c.name == inheritance_column }
end
inheritance_column() click to toggle source

The name of the column containing the object's class when Single Table Inheritance is used

# File lib/active_record/model_schema.rb, line 160
def inheritance_column
  if self == Base
    'type'
  else
    (@inheritance_column ||= nil) || superclass.inheritance_column
  end
end
inheritance_column=(value) click to toggle source

Sets the value of inheritance_column

# File lib/active_record/model_schema.rb, line 173
def inheritance_column=(value)
  @original_inheritance_column = inheritance_column
  @inheritance_column          = value.to_s
end
quoted_table_name() click to toggle source

Returns a quoted version of the table name, used to construct SQL statements.

# File lib/active_record/model_schema.rb, line 136
def quoted_table_name
  @quoted_table_name ||= connection.quote_table_name(table_name)
end
reset_column_information() click to toggle source

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
# File lib/active_record/model_schema.rb, line 297
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
sequence_name() click to toggle source
# File lib/active_record/model_schema.rb, line 182
def sequence_name
  if base_class == self
    @sequence_name ||= reset_sequence_name
  else
    (@sequence_name ||= nil) || base_class.sequence_name
  end
end
sequence_name=(value) click to toggle source

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
# File lib/active_record/model_schema.rb, line 212
def sequence_name=(value)
  @original_sequence_name = @sequence_name if defined?(@sequence_name)
  @sequence_name          = value.to_s
end
table_exists?() click to toggle source

Indicates whether the table associated with this class exists

# File lib/active_record/model_schema.rb, line 222
def table_exists?
  connection.schema_cache.table_exists?(table_name)
end
table_name() click to toggle source

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 super to manipulate the default table name.) Example:

class Post < ActiveRecord::Base
  def self.table_name
    "special_" + super
  end
end
Post.table_name # => "special_posts"
# File lib/active_record/model_schema.rb, line 103
def table_name
  reset_table_name unless defined?(@table_name)
  @table_name
end
table_name=(value) click to toggle source

Sets the table name explicitly. Example:

class Project < ActiveRecord::Base
  self.table_name = "project"
end

You can also just define your own self.table_name method; see the documentation for ActiveRecord::Base#table_name.

# File lib/active_record/model_schema.rb, line 120
def table_name=(value)
  @original_table_name = @table_name if defined?(@table_name)
  @table_name          = value && value.to_s
  @quoted_table_name   = nil
  @arel_table          = nil
  @relation            = Relation.new(self, arel_table)
end

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