abstract class DB::ResultSet

• DB::ResultSet
• Reference
• Object

Overview

The response of a query performed on a Database.

See DB for a complete sample.

Each #read call consumes the result and moves to the next column. Each column must be read in order. At any moment a #move_next can be invoked, meaning to skip the remaining, or even all the columns, in the current row. Also it is not mandatory to consume the whole ResultSet, hence an iteration through #each or #move_next can be stopped.

Note: depending on how the ResultSet was obtained it might be mandatory an explicit call to #close. Check QueryMethods#query.

Note to implementors

1. Override #move_next to move to the next row.
2. Override #read returning the next value in the row.
3. (Optional) Override #read(t) for some types t for which custom logic other than a simple cast is needed.
4. Override #column_count, #column_name.

Included Modules

• DB::Disposable

Defined in:

Constructors

• .new(statement : DB::Statement)

Instance Method Summary

• #column_count : Int32

  Returns the number of columns in the result

• #column_name(index : Int32) : String

  Returns the name of the column in index 0-based position.

• #column_names

  Returns the name of the columns.

• #each(&)

  Iterates over all the rows

• #each_column(&)

  Iterates over all the columns

• #move_next : Bool

  Move the next row in the result.

• #next_column_index : Int32

  Returns the column index that corresponds to the next #read.

• #read(type : Enum.class)

  Read the value based on the given enum type, supporting both string and numeric column types.

• #read(type : DB::Mappable.class)

  Reads the next columns and maps them to a class

• #read(type : T.class) : T forall T

  Reads the next column value as a type

• #read

  Reads the next column value

• #read(*types : Class)

  Reads the next columns and returns a tuple of the values.

• #read(**types : Class)

  Reads the next columns and returns a named tuple of the values.

Constructor Detail

Instance Method Detail

enum Status
  Pending
  Complete
end

db.query "SELECT 'complete'" do |rs|
  rs.read Status # => Status::Complete
end