Class: Montage::QueryParser

Inherits:
Object
  • Object
show all
Includes:
Support
Defined in:
lib/montage/query/query_parser.rb

Constant Summary collapse

TYPE_MAP = 
{
  is_i?: :to_i,
  is_f?: :to_f,
  is_s?: :to_s
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from Support

#is_f?, #is_i?, #nillify

Constructor Details

#initialize(query) ⇒ QueryParser

Creates a QueryParser instance based on a query argument. The instance can then be parsed into a ReQON compatible array and used as a filter for queries

  • Args :

    • query -> A hash or string that includes the database column name, a logical operator, and the associated value

  • Returns :

    • A Montage::QueryParser instance



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# File 'lib/montage/query/query_parser.rb', line 28

def initialize(query)
  @query = query
end

Instance Attribute Details

#query ⇒ Object (readonly)

Returns the value of attribute query.



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# File 'lib/montage/query/query_parser.rb', line 10

def query
  @query
end

Instance Method Details

#get_column_name(part, splitter = " ") ⇒ Object

Parse the column name from the specific query part

  • Args :

    • part -> The query string

    • splitter -> The value to split on

  • Returns :

    • A string value for the provided column name

  • Examples :

    @part = "bobross = 'amazing'"
get_column_name(@part, " ")
=> "bobross"



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# File 'lib/montage/query/query_parser.rb', line 44

def get_column_name(part, splitter = " ")
  part.downcase.split(splitter)[0].strip
end

#get_parts(str) ⇒ Object

Get all the parts of the query string

  • Args :

    • str -> The query string

  • Returns :

    • An array containing the column name, the montage operator, and the value for comparison.

  • Raises :

    • QueryError -> When incomplete queries or queries without valid operators are initialized

  • Examples :

    @part = "tree_happiness_level > 9"
get_parts(@part)
=> ["tree_happiness_level", "$gt", 9]



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# File 'lib/montage/query/query_parser.rb', line 125

def get_parts(str)
  operator, montage_operator = get_query_operator(str)

  fail QueryError, "Invalid Montage query operator!" unless montage_operator

  column_name = get_column_name(str, operator)

  fail QueryError, "Your query has an undetermined error" unless column_name

  value = parse_part(parse_condition_set(str, operator))

  [column_name, montage_operator, value]
end

#get_query_operator(part) ⇒ Object

Grabs the proper query operator from the string

  • Args :

    • part -> The query string

  • Returns :

    • An array containing the supplied logical operator and the Montage equivalent

  • Examples :

    @part = "tree_happiness_level > 9"
get_query_operator(@part)
=> [">", "$gt"]



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# File 'lib/montage/query/query_parser.rb', line 60

def get_query_operator(part)
  operator = Montage::Operators.find_operator(part)
  [operator.operator, operator.montage_operator]
end

#parse ⇒ Object

Determines query datatype and triggers the correct parsing



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# File 'lib/montage/query/query_parser.rb', line 179

def parse
  if query.is_a?(Hash)
    parse_hash
  else
    parse_string
  end
end

#parse_condition_set(clause, splitter = " ") ⇒ Object

Extract the condition set from the given clause

  • Args :

    • clause -> The query string

    • splitter -> The logical operator to split on

  • Returns :

    • The value portion of the query

  • Examples :

    @part = "tree_happiness_level > 9"
parse_condition_set(@part, "<")
=> "9"



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# File 'lib/montage/query/query_parser.rb', line 77

def parse_condition_set(clause, splitter = " ")
  clause.split(/#{splitter}/i)[-1].strip
end

#parse_hash ⇒ Object

Parse a hash type query

  • Returns :

    • A ReQON compatible array

  • Examples :

    @test = Montage::QueryParser.new(tree_status: "happy")
@test.parse_hash
=> [["tree_status", "happy"]]



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# File 'lib/montage/query/query_parser.rb', line 148

def parse_hash
  query.map do |key, value|
    new_value = value.is_a?(Array) ? ["$in", value] : value
    [key.to_s, new_value]
  end
end

#parse_part(part) ⇒ Object

Parse a single portion of the query string. String values representing a float or integer are coerced into actual numerical values. Newline characters are removed and single quotes are replaced with double quotes

  • Args :

    • part -> The value element extracted from the query string

  • Returns :

    • A parsed form of the value element

  • Examples :

    @part = "9"
parse_part(@part)
=> 9



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# File 'lib/montage/query/query_parser.rb', line 94

def parse_part(part)
  parsed_part = JSON.parse(part) rescue part

  if is_i?(parsed_part)
    parsed_part.to_i
  elsif is_f?(parsed_part)
    parsed_part.to_f
  elsif parsed_part =~ /\(.*\)/
    to_array(parsed_part)
  elsif parsed_part.is_a?(Array)
    parsed_part
  else
    parsed_part.gsub(/('|')/, "")
  end
end

#parse_string ⇒ Object

Parse a string type query. Splits multiple conditions on case insensitive “and” strings that do not fall within single quotations. Note that the Montage equals operator is supplied as a blank string

  • Returns :

    • A ReQON compatible array

  • Examples :

    @test = Montage::QueryParser.new("tree_happiness_level > 9")
@test.parse_string
=> [["tree_happiness_level", ["$__gt", 9]]]



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# File 'lib/montage/query/query_parser.rb', line 166

def parse_string
  query.split(/\band\b(?=(?:[^']|'[^']*')*$)/i).map do |part|
    column_name, operator, value = get_parts(part)
    if operator == ""
      ["#{column_name}", value]
    else
      ["#{column_name}", ["#{operator}", value]]
    end
  end
end

#to_array(value) ⇒ Object

Takes a string value and splits it into an array Will coerce all values into the type of the first type

  • Args :

    • value -> A string value

  • Returns :

    • A array form of the value argument

  • Examples :

    @part = "(1, 2, 3)"
to_array(@part)
=> [1, 2, 3]



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# File 'lib/montage/query/query_parser.rb', line 199

def to_array(value)
  values = value.gsub(/('|\(|\))/, "").split(',')
  type = [:is_i?, :is_f?].find(Proc.new { :is_s? }) { |t| send(t, values.first) }
  values.map { |v| v.send(TYPE_MAP[type]) }
end