Class: Hash

Inherits:
Object show all
Defined in:
lib/m4dbi/hash.rb

Constant Summary collapse

COMPACT_NILS = 
true
DONT_COMPACT_NILS = 
false

Instance Method Summary collapse

Instance Method Details

#slice(*desired_keys) ⇒ Object 



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# File 'lib/m4dbi/hash.rb', line 42

def slice( *desired_keys )
  Hash[
    *(
      select { |key,value|
        desired_keys.include? key
      }.flatten
    )
  ]
end

#to_clause(join_string, compact_nils = DONT_COMPACT_NILS) ⇒ Object

Takes an optional block to provide a single “field = ?” type subclause for each key-value pair.



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# File 'lib/m4dbi/hash.rb', line 7

def to_clause( join_string, compact_nils = DONT_COMPACT_NILS )
  # The clause items and the values have to be in the same order.
  keys_ = keys
  if block_given?
    mapping = keys_.map { |field| yield field }
  else
    mapping = keys_.map { |field| "#{field} = ?" }
  end
  clause = mapping.join( join_string )
  values_ = keys_.map { |key|
    self[ key ]
  }
  if compact_nils
    values_.compact!
  end
  [ clause, values_ ]
end

#to_set_clause ⇒ Object 



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# File 'lib/m4dbi/hash.rb', line 35

def to_set_clause
  to_clause( ", " )
end

#to_where_clause ⇒ Object 



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# File 'lib/m4dbi/hash.rb', line 25

def to_where_clause
  to_clause( " AND ", COMPACT_NILS ) { |field|
    if self[ field ].nil?
      "#{field} IS NULL"
    else
      "#{field} = ?"
    end
  }
end