Class: ScopedSearch::QueryBuilder

Inherits:
Object
  • Object
show all
Defined in:
lib/scoped_search/query_builder.rb

Overview

The QueryBuilder class builds an SQL query based on aquery string that is provided to the search_for named scope. It uses a SearchDefinition instance to shape the query.

Direct Known Subclasses

Mysql2Adapter, MysqlAdapter, OracleEnhancedAdapter, PostgreSQLAdapter

Defined Under Namespace

Modules: AST, Field Classes: Mysql2Adapter, MysqlAdapter, OracleEnhancedAdapter, PostgreSQLAdapter

Constant Summary

SQL_OPERATORS =

A hash that maps the operators of the query language with the corresponding SQL operator.

{ :eq =>'=',  :ne => '<>', :like => 'LIKE', :unlike => 'NOT LIKE',
:gt => '>', :lt =>'<',   :lte => '<=',    :gte => '>=',
:in => 'IN',:notin => 'NOT IN' }

Instance Attribute Summary (collapse)

Class Method Summary (collapse)

Instance Method Summary (collapse)

Constructor Details

- (QueryBuilder) initialize(definition, ast, profile)

Initializes the instance by setting the relevant parameters



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# File 'lib/scoped_search/query_builder.rb', line 40

def initialize(definition, ast, profile)
  @definition, @ast, @definition.profile = definition, ast, profile
end

Instance Attribute Details

- (Object) ast (readonly)

Returns the value of attribute ast



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# File 'lib/scoped_search/query_builder.rb', line 8

def ast
  @ast
end

- (Object) definition (readonly)

Returns the value of attribute definition



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# File 'lib/scoped_search/query_builder.rb', line 8

def definition
  @definition
end

Class Method Details

+ (Object) build_query(definition, *args)

Creates a find parameter hash that can be passed to ActiveRecord::Base#find, given a search definition and query string. This method is called from the search_for named scope.

This method will parse the query string and build an SQL query using the search query. It will return an empty hash if the search query is empty, in which case the scope call will simply return all records.



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# File 'lib/scoped_search/query_builder.rb', line 17

def self.build_query(definition, *args)
  query = args[0] ||=''
  options = args[1] || {}

  query_builder_class = self.class_for(definition)
  if query.kind_of?(ScopedSearch::QueryLanguage::AST::Node)
    return query_builder_class.new(definition, query, options[:profile]).build_find_params(options)
  elsif query.kind_of?(String)
    return query_builder_class.new(definition, ScopedSearch::QueryLanguage::Compiler.parse(query), options[:profile]).build_find_params(options)
  else
    raise "Unsupported query object: #{query.inspect}!"
  end
end

+ (Object) class_for(definition)

Loads the QueryBuilder class for the connection of the given definition. If no specific adapter is found, the default QueryBuilder class is returned.



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# File 'lib/scoped_search/query_builder.rb', line 33

def self.class_for(definition)
  self.const_get(definition.klass.connection.class.name.split('::').last)
rescue
  self
end

Instance Method Details

- (Object) build_find_params(options)

Actually builds the find parameters hash that should be used in the search_for named scope.



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# File 'lib/scoped_search/query_builder.rb', line 46

def build_find_params(options)
  keyconditions = []
  keyparameters = []
  parameters = []
  includes   = []
  joins   = []

  # Build SQL WHERE clause using the AST
  sql = @ast.to_sql(self, definition) do |notification, value|

    # Handle the notifications encountered during the SQL generation:
    # Store the parameters, includes, etc so that they can be added to
    # the find-hash later on.
    case notification
      when :keycondition then keyconditions << value
      when :keyparameter then keyparameters << value
      when :parameter    then parameters    << value
      when :include      then includes      << value
      when :joins        then joins         << value
      else raise ScopedSearch::QueryNotSupported, "Cannot handle #{notification.inspect}: #{value.inspect}"
    end
  end
    # Build SQL ORDER BY clause
  order = order_by(options[:order]) do |notification, value|
    case notification
      when :parameter then parameters << value
      when :include   then includes   << value
      when :joins     then joins      << value
      else raise ScopedSearch::QueryNotSupported, "Cannot handle #{notification.inspect}: #{value.inspect}"
    end
  end
  sql = (keyconditions + (sql.blank? ? [] : [sql]) ).map {|c| "(#{c})"}.join(" AND ")
  # Build hash for ActiveRecord::Base#find for the named scope
  find_attributes = {}
  find_attributes[:conditions] = [sql] + keyparameters + parameters unless sql.blank?
  find_attributes[:include]    = includes.uniq                      unless includes.empty?
  find_attributes[:joins]      = joins.uniq                         unless joins.empty?
  find_attributes[:order]      = order                              unless order.nil?

  # p find_attributes # Uncomment for debugging
  return find_attributes
end

- (Object) datetime_test(field, operator, value) {|:parameter, timestamp| ... }

Perform a comparison between a field and a Date(Time) value.

This function makes sure the date is valid and adjust the comparison in some cases to return more logical results.

This function needs a block that can be used to pass other information about the query (parameters that should be escaped, includes) to the query builder.

field

The field to test.

operator

The operator used for comparison.

value

The value to compare the field with.

Yields:

  • (:parameter, timestamp) 


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# File 'lib/scoped_search/query_builder.rb', line 131

def datetime_test(field, operator, value, &block) # :yields: finder_option_type, value

  # Parse the value as a date/time and ignore invalid timestamps
  timestamp = definition.parse_temporal(value)
  return nil unless timestamp

  timestamp = timestamp.to_date if field.date?
  # Check for the case that a date-only value is given as search keyword,
  # but the field is of datetime type. Change the comparison to return
  # more logical results.
  if field.datetime?
    span = 1.minute if(value =~ /\A\s*\d+\s+\bminutes?\b\s+\bago\b\s*\z/i)
    span ||= (timestamp.day_fraction == 0) ? 1.day : 1.hour
    if [:eq, :ne].include?(operator)
      # Instead of looking for an exact (non-)match, look for dates that
      # fall inside/outside the range of timestamps of that day.
      yield(:parameter, timestamp)
      yield(:parameter, timestamp + span)
      negate    = (operator == :ne) ? 'NOT ' : ''
      field_sql = field.to_sql(operator, &block)
      return "#{negate}(#{field_sql} >= ? AND #{field_sql} < ?)"

    elsif operator == :gt
      # Make sure timestamps on the given date are not included in the results
      # by moving the date to the next day.
      timestamp += span
      operator = :gte

    elsif operator == :lte
      # Make sure the timestamps of the given date are included by moving the
      # date to the next date.
      timestamp += span
      operator = :lt
    end
  end

  # Yield the timestamp and return the SQL test
  yield(:parameter, timestamp)
  "#{field.to_sql(operator, &block)} #{sql_operator(operator, field)} ?"
end

- (Object) order_by(order, &block)

Raises:



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# File 'lib/scoped_search/query_builder.rb', line 89

def order_by(order, &block)
  order ||= definition.default_order
  return nil if order.blank?
  field = definition.field_by_name(order.to_s.split(' ')[0])
  raise ScopedSearch::QueryNotSupported, "the field '#{order.to_s.split(' ')[0]}' in the order statement is not valid field for search" unless field
  sql = field.to_sql(&block)
  direction = (order.to_s.downcase.include?('desc')) ? " DESC" : " ASC"
  order = sql + direction

  return order
end

- (Object) set_test(field, operator, value) {|:parameter, set_value| ... }

A 'set' is group of possible values, for example a status might be “on”, “off” or “unknown” and the database representation could be for example a numeric value. This method will validate the input and translate it into the database representation.

Yields:

  • (:parameter, set_value)

Raises:



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# File 'lib/scoped_search/query_builder.rb', line 181

def set_test(field, operator,value, &block)
  set_value = translate_value(field, value)
  raise ScopedSearch::QueryNotSupported, "Operator '#{operator}' not supported for '#{field.field}'" unless [:eq,:ne].include?(operator)
  negate = ''
  if [true,false].include?(set_value)
    negate = 'NOT ' if operator == :ne
    if field.numerical?
      operator =  (set_value == true) ?  :gt : :eq
      set_value = 0
    else
      operator = (set_value == true) ? :ne : :eq
      set_value = false
    end
  end
  yield(:parameter, set_value)
  return "#{negate}(#{field.to_sql(operator, &block)} #{self.sql_operator(operator, field)} ?)"
end

- (Object) sql_operator(operator, field)

Return the SQL operator to use given an operator symbol and field definition.

By default, it will simply look up the correct SQL operator in the SQL_OPERATORS hash, but this can be overridden by a database adapter.

Raises:



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# File 'lib/scoped_search/query_builder.rb', line 110

def sql_operator(operator, field)
  raise ScopedSearch::QueryNotSupported, "the operator '#{operator}' is not supported for field type '#{field.type}'" if [:like, :unlike].include?(operator) and !field.textual?
  SQL_OPERATORS[operator]
end

- (Object) sql_test(field, operator, value, lhs) {|:keyparameter, lhs.sub(/^.*\./,'')| ... }

Generates a simple SQL test expression, for a field and value using an operator.

This function needs a block that can be used to pass other information about the query (parameters that should be escaped, includes) to the query builder.

field

The field to test.

operator

The operator used for comparison.

value

The value to compare the field with.

Yields:

  • (:keyparameter, lhs.sub(/^.*\./,'')) 


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# File 'lib/scoped_search/query_builder.rb', line 207

def sql_test(field, operator, value, lhs, &block) # :yields: finder_option_type, value
  return field.to_ext_method_sql(lhs, sql_operator(operator, field), value, &block) if field.ext_method

  yield(:keyparameter, lhs.sub(/^.*\./,'')) if field.key_field

  if [:like, :unlike].include?(operator)
    yield(:parameter, (value !~ /^\%|\*/ && value !~ /\%|\*$/) ? "%#{value}%" : value.tr_s('%*', '%'))
    return "#{field.to_sql(operator, &block)} #{self.sql_operator(operator, field)} ?"
  elsif [:in, :notin].include?(operator)
    value.split(',').collect { |v| yield(:parameter, field.set? ? translate_value(field, v) : v.strip) }
    value = value.split(',').collect { "?" }.join(",")
    return "#{field.to_sql(operator, &block)} #{self.sql_operator(operator, field)} (#{value})"
  elsif field.temporal?
    return datetime_test(field, operator, value, &block)
  elsif field.set?
    return set_test(field, operator, value, &block)
  elsif field.definition.klass.reflections[field.relation].try(:macro) == :has_many
    value = value.to_i if field.offset
    yield(:parameter, value)
    return "#{field.definition.klass.table_name}.id IN (SELECT #{field.reflection_keys(field.definition.klass.reflections[field.relation])[1]} FROM #{field.klass.table_name} WHERE #{field.to_sql(operator, &block)} #{self.sql_operator(operator, field)} ? )"
  else
    value = value.to_i if field.offset
    yield(:parameter, value)
    return "#{field.to_sql(operator, &block)} #{self.sql_operator(operator, field)} ?"
  end
end

- (Object) to_not_sql(rhs, definition, &block)

Returns a NOT (…) SQL fragment that negates the current AST node's children



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# File 'lib/scoped_search/query_builder.rb', line 116

def to_not_sql(rhs, definition, &block)
  "NOT COALESCE(#{rhs.to_sql(self, definition, &block)}, 0)"
end

- (Object) translate_value(field, value)

Validate the key name is in the set and translate the value to the set value.

Raises:



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# File 'lib/scoped_search/query_builder.rb', line 173

def translate_value(field, value)
  translated_value = field.complete_value[value.to_sym]
  raise ScopedSearch::QueryNotSupported, "'#{field.field}' should be one of '#{field.complete_value.keys.join(', ')}', but the query was '#{value}'" if translated_value.nil?
  translated_value
end