Class: SQLite::ResultSet

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/sqlite/resultset.rb

Overview

The ResultSet object encapsulates the enumerability of a query’s output. It is a simple cursor over the data that the query returns. It will very rarely (if ever) be instantiated directly. Instead, client’s should obtain a ResultSet instance via Statement#execute.

Defined Under Namespace

Modules: FieldsContainer, TypesContainer

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(db, sql) ⇒ ResultSet

Create a new ResultSet attached to the given database, using the given sql text.



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# File 'lib/sqlite/resultset.rb', line 62

def initialize( db, sql )
  @db = db
  @sql = sql
  commence
end

Instance Attribute Details

#columns ⇒ Object (readonly)

An array of the column names for this result set (may be empty)



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# File 'lib/sqlite/resultset.rb', line 55

def columns
  @columns
end

#types ⇒ Object (readonly)

An array of the column types for this result set (may be empty)



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# File 'lib/sqlite/resultset.rb', line 58

def types
  @types
end

Instance Method Details

#close ⇒ Object

Close the result set. Attempting to perform any operation (including #close) on a closed result set will have undefined results.



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# File 'lib/sqlite/resultset.rb', line 90

def close
  API.finalize( @vm )
end

#each ⇒ Object

Required by the Enumerable mixin. Provides an internal iterator over the rows of the result set.



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# File 'lib/sqlite/resultset.rb', line 160

def each
  while row=self.next
    yield row
  end
end

#eof? ⇒ Boolean

Query whether the cursor has reached the end of the result set or not.

Returns:

  • (Boolean) 


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# File 'lib/sqlite/resultset.rb', line 104

def eof?
  @eof
end

#next ⇒ Object

Obtain the next row from the cursor. If there are no more rows to be had, this will return nil. If type translation is active on the corresponding database, the values in the row will be translated according to their types.

The returned value will be an array, unless Database#results_as_hash has been set to true, in which case the returned value will be a hash.

For arrays, the column names are accessible via the fields property, and the column types are accessible via the types property.

For hashes, the column names are the keys of the hash, and the column types are accessible via the types property.



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# File 'lib/sqlite/resultset.rb', line 121

def next
  return nil if @eof

  if @current_row
    result, @current_row = @current_row, nil
  else
    result = API.step( @vm )
    check_eof( result )
  end

  unless @eof
    row = result[:row]

    if @db.type_translation
      row = @types.zip( row ).map do |type, value|
        @db.translator.translate( type, value )
      end
    end

    if @db.results_as_hash
      new_row = Hash[ *( @columns.zip( row ).flatten ) ]
      row.each_with_index { |value,idx| new_row[idx] = value }
      row = new_row
    else
      row.extend FieldsContainer unless row.respond_to?(:fields)
      row.fields = @columns
    end

    row.extend TypesContainer
    row.types = @types

    return row
  end

  nil
end

#reset ⇒ Object

Reset the cursor, so that a result set which has reached end-of-file can be rewound and reiterated. Note: this uses an experimental API, which is subject to change. Use at your own risk.



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# File 'lib/sqlite/resultset.rb', line 97

def reset
  API.finalize( @vm )
  commence
  @eof = false
end