### Home Classes Methods

### In Files

- lib/active_record/connection_adapters/schema_cache.rb

### Parent

Object

### Methods

- ::new
- #clear!
- #clear_table_cache!
- #columns
- #columns_hash
- #table_exists?

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- README.rdoc

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No matching classes.

# ActiveRecord::ConnectionAdapters::SchemaCache

### Attributes

connection[R]
primary_keys[R]
tables[R]

### Public Class Methods

new(conn) click to toggle source

    # File lib/active_record/connection_adapters/schema_cache.rb, line 7
    def initialize(conn)
      @connection = conn
      @tables     = {}

      @columns = Hash.new do |h, table_name|
        h[table_name] = connection.columns(table_name, "#{table_name} Columns")
      end

      @columns_hash = Hash.new do |h, table_name|
        h[table_name] = Hash[columns[table_name].map { |col|
          [col.name, col]
        }]
      end

      @primary_keys = Hash.new do |h, table_name|
        h[table_name] = table_exists?(table_name) ? connection.primary_key(table_name) : nil
      end
    end

### Public Instance Methods

clear!() click to toggle source

Clears out internal caches

    # File lib/active_record/connection_adapters/schema_cache.rb, line 53
    def clear!
      @columns.clear
      @columns_hash.clear
      @primary_keys.clear
      @tables.clear
    end

clear_table_cache!(table_name) click to toggle source

Clear out internal caches for table with `table_name`.

    # File lib/active_record/connection_adapters/schema_cache.rb, line 61
    def clear_table_cache!(table_name)
      @columns.delete table_name
      @columns_hash.delete table_name
      @primary_keys.delete table_name
      @tables.delete table_name
    end

columns(table = nil) click to toggle source

Get the columns for a table

    # File lib/active_record/connection_adapters/schema_cache.rb, line 34
    def columns(table = nil)
      if table
        @columns[table]
      else
        @columns
      end
    end

columns_hash(table = nil) click to toggle source

Get the columns for a table as a hash, key is the column name value is the column object.

    # File lib/active_record/connection_adapters/schema_cache.rb, line 44
    def columns_hash(table = nil)
      if table
        @columns_hash[table]
      else
        @columns_hash
      end
    end

table_exists?(name) click to toggle source

A cached lookup for table existence.

    # File lib/active_record/connection_adapters/schema_cache.rb, line 27
    def table_exists?(name)
      return @tables[name] if @tables.key? name

      @tables[name] = connection.table_exists?(name)
    end

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