Module: DataMapper::Reflection::PostgresAdapter

Defined in:
lib/dm-reflection/adapters/postgres.rb

Overview

TODO:

The postgres adapter extensions have not been tested yet.

Instance Method Summary collapse

Instance Method Details

#get_primary_keys(table) ⇒ Array<String>

Returna list of columns in the primary key

Parameters:

  • the (String) —

    table name

Returns:

  • (Array<String>) —

    the names of the columns in the primary key



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# File 'lib/dm-reflection/adapters/postgres.rb', line 55

def get_primary_keys(table)
  select(<<-SQL.compress_lines, table).to_set
        SELECT "key_column_usage"."column_name"
          FROM "information_schema"."table_constraints"
    INNER JOIN "information_schema"."key_column_usage" USING("constraint_schema", "constraint_name")
         WHERE "table_constraints"."constraint_type" = 'PRIMARY KEY'
           AND "table_constraints"."table_name" = ?
  SQL
end

#get_properties(table) ⇒ Hash

TODO:

Consider returning actual DataMapper::Properties from this. It would probably require passing in a Model Object.

Get the column specifications for a specific table

Parameters:

  • table (String) —

    the name of the table to get column specifications for

Returns:

  • (Hash) —

    the column specs are returned in a hash keyed by ‘:name`, `:field`, `:type`, `:required`, `:default`, `:key`



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# File 'lib/dm-reflection/adapters/postgres.rb', line 74

def get_properties(table)
  columns = select(<<-SQL.compress_lines, schema_name, table)
      SELECT "column_name"
           , "data_type"
           , "column_default"
           , "is_nullable"
           , "character_maximum_length"
           , "numeric_precision"
        FROM "information_schema"."columns"
       WHERE "table_schema" = ?
         AND "table_name" = ?
    ORDER BY "ordinal_position"
  SQL

  primary_keys = get_primary_keys(table)

  columns.map do |column|
    type     = get_type(column.data_type)
    default  = column.column_default
    required = column.is_nullable == 'NO'
    key      = primary_keys.include?(column.column_name)
    length   = column.character_maximum_length

    if type == Integer && default
      if key
        type    = DataMapper::Types::Serial if default[/\Anextval/]
        default = nil
      else
        default = default.to_i
      end
    end

    if length
      length = (required ? 1 : 0)..length
    end
    
    field_name = column.column_name.downcase

    attribute = {
      :name     => field_name,
      :type     => type,
      :required => required,
      :default  => default,
      :key      => key,
      :length   => length,
    }

    if type == Integer && field_name[-3,3] == "_id"
      # This is a foriegn key. So this model belongs_to the other (_id) one.
      # Add a special set of values and flag this as a relationship so the reflection code
      # can rebuild the relationship when it's building the model.
      attribute[:type] = DataMapper::Associations::Relationship
      attribute[:relationship] = { 
        :parent => ActiveSupport::Inflector.classify(field_name[0..-4]), 
        :child => ActiveSupport::Inflector.classify(table), 
        # When we can detect more from the database we can optimize this
        :cardinality => Infinity, 
        :bidirectional => true }
    end

    # TODO: use the naming convention to compare the name vs the column name
    unless attribute[:name] == column.column_name
      attribute[:field] = column.column_name
    end

    attribute
  end
end

#get_storage_names ⇒ String Array

Get the list of table names

Returns:

  • (String Array) —

    the names of the tables in the database.



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# File 'lib/dm-reflection/adapters/postgres.rb', line 41

def get_storage_names
  select(<<-SQL.compress_lines)
    SELECT "relname"
      FROM "pg_stat_user_tables"
     WHERE "schemaname" = 'public'
  SQL
end

#get_type(db_type) ⇒ Type

TODO:

This should be verified to identify all mysql primitive types and that they map to the correct DataMapper/Ruby types.

Convert the database type into a DataMapper type

Parameters:

  • db_type (String) —

    type specified by the database

Returns:

  • (Type) —

    a DataMapper or Ruby type object.



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# File 'lib/dm-reflection/adapters/postgres.rb', line 17

def get_type(db_type)
  {
    'integer'                     =>  Integer        ,
    'varchar'                     =>  String         ,
    'character varying'           =>  String         ,
    'numeric'                     =>  BigDecimal     ,
    'double precision'            =>  Float          ,
    'datetime'                    =>  DateTime       ,
    'date'                        =>  Date           ,
    'boolean'                     =>  Types::Boolean ,
    'text'                        =>  Types::Text    ,
    'timestamp without time zone' =>  DateTime       ,
  }[db_type] || raise("unknown db type: #{db_type}")
end

#separator ⇒ Object 



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# File 'lib/dm-reflection/adapters/postgres.rb', line 32

def separator
  '--'
end