Class: Kasket::QueryParser

Inherits:
Object
  • Object
show all
Defined in:
lib/kasket/query_parser.rb

Constant Summary collapse

AND =

Examples: SELECT * FROM ‘users` WHERE (`users`.`id` = 2) SELECT * FROM `users` WHERE (`users`.`id` = 2) LIMIT 1 ’SELECT * FROM 'posts' WHERE ('posts'.'id' = 574019247) ‘

/\s+AND\s+/i
VALUE =

Matches: 123, ?, ‘123’, ‘12”3’

/'?(\d+|\?|(?:(?:[^']|''|\\')*))'?/

Instance Method Summary collapse

Constructor Details

#initialize(model_class) ⇒ QueryParser

Returns a new instance of QueryParser.



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# File 'lib/kasket/query_parser.rb', line 12

def initialize(model_class)
  @model_class = model_class
  @supported_query_pattern = if AR30
    /^select\s+(?:`#{@model_class.table_name}`.)?\* from (?:`|")#{@model_class.table_name}(?:`|") where (.*?)\s*$/i
  else
    /^select \* from (?:`|")#{@model_class.table_name}(?:`|") where \((.*)\)(|\s+limit 1)\s*$/i
  end
  @table_and_column_pattern = /(?:(?:`|")?#{@model_class.table_name}(?:`|")?\.)?(?:`|")?([a-zA-Z]\w*)(?:`|")?/ # Matches: `users`.id, `users`.`id`, users.id, id
  @key_eq_value_pattern = /^[\(\s]*#{@table_and_column_pattern}\s+(=|IN)\s+#{VALUE}[\)\s]*$/ # Matches: KEY = VALUE, (KEY = VALUE), ()(KEY = VALUE))
end

Instance Method Details

#parse(sql) ⇒ Object 



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# File 'lib/kasket/query_parser.rb', line 23

def parse(sql)
  if match = @supported_query_pattern.match(sql)
    where, limit = match[1], match[2]
    if AR30
      return if where =~ / (order by|group by|join|having) /i
      if where =~ /limit \d+\s*$/i
        # limit is harder to find in rails 3.0 since where does not use surrounding braces
        return unless where =~ /(.*?)(\s+limit 1)\s*$/i
        where, limit = $1, $2
      end
    end

    query = Hash.new
    query[:attributes] = sorted_attribute_value_pairs(where)
    return nil if query[:attributes].nil?

    if query[:attributes].size > 1 && query[:attributes].map(&:last).any? {|a| a.is_a?(Array)}
      # this is a query with IN conditions AND other conditions
      return nil
    end

    query[:index] = query[:attributes].map(&:first)
    query[:limit] = limit.blank? ? nil : 1
    query[:key] = @model_class.kasket_key_for(query[:attributes])
    query[:key] << '/first' if query[:limit] == 1 && !query[:index].include?(:id)
    query
  end
end