Module: ActiveRecord::ModelSchema::ClassMethods

### Home Classes Methods

### In Files

- lib/active_record/model_schema.rb

### Methods

- #column_defaults
- #column_names
- #columns
- #columns_hash
- #content_columns
- #inheritance_column
- #inheritance_column=
- #quoted_table_name
- #reset_column_information
- #sequence_name
- #sequence_name=
- #table_exists?
- #table_name
- #table_name=

### Files

- README.rdoc

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No matching classes.

# 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 243
    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 248
    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 228
    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 237
    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 254
    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
        (@inheritance_column ||= nil) || '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
      @explicit_inheritance_column = true
    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 298
    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 = nil
      @inheritance_column = nil unless defined?(@explicit_inheritance_column) && @explicit_inheritance_column
      @arel_engine = @relation = nil
    end

sequence_name() click to toggle source

    # File lib/active_record/model_schema.rb, line 183
    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 213
    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 223
    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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