Module: Queryfy

Extended by:
Configuration
Defined in:
lib/queryfy.rb,
lib/queryfy/version.rb

Constant Summary collapse

VERSION = 
"0.2.2"

Class Method Summary collapse

Methods included from Configuration

configuration, define_setting

Class Method Details

.build_query(klass, querystring, limit = 50, offset = 0) ⇒ Object

Actually builds the query



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# File 'lib/queryfy.rb', line 14

def self.build_query(klass, querystring, limit = 50, offset = 0)
  limit = [max_limit, limit.to_i].min
  offset = offset.to_i
  # Handle empty and nil queries
  if (querystring.nil? || querystring == '')
    return {
      data: klass.limit(limit).offset(offset), 
      count: klass.all.count, 
      limit: limit.to_i, offset: offset.to_i
    }
  end

  begin
    tree = FilterLexer::Parser.parse(querystring)
  rescue FilterLexer::ParseException => e
    raise FilterParseError, "Failed to parse querystring, #{ e.message }"
    return
  end

  # Build the query with pagination
  query = klass.arel_table.project(Arel.star).take(limit).skip(offset)

  cleaned_tree = self.clean_tree(tree)
  arel_tree = self.cleaned_to_arel(klass.arel_table, cleaned_tree)
  # If we want to actually query, add the conditions to query
  query = query.where(arel_tree) unless arel_tree.nil?

  total = 0
  if arel_tree.nil?
    total = klass.all.count
  else
    countquery = klass.arel_table.project(klass.arel_table[klass.primary_key.to_sym].count.as('total')).where(arel_tree)
    results = klass.connection.execute(countquery.to_sql)
    if results.count == 0
      raise QueryfyError, 'Failed to select count, this should not happen'
    else
      total = results[0]['total']
    end
  end

  # Return the results
  return {data: klass.find_by_sql(query.to_sql), count: total.to_i, limit: limit.to_i, offset: offset.to_i}
end

.clean_tree(tree, input = []) ⇒ Object

Cleans the filterlexer tree Output is an array with either filterentries and operators, or an array of filterentries and operators The latter represents a group



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# File 'lib/queryfy.rb', line 61

def self.clean_tree(tree, input = [])
  tree.elements.each do |el|
    if el.is_a?(FilterLexer::Expression)
      input += clean_tree(el)
    elsif el.is_a?(FilterLexer::Group)
      input += [clean_tree(el)]
    else
      input.push(el)
    end
  end
  return input
end

.cleaned_to_arel(arel_table, tree, ast = nil) ⇒ Object

Converts a cleaned tree to something arel can understand



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# File 'lib/queryfy.rb', line 75

def self.cleaned_to_arel(arel_table, tree, ast = nil)
  tree.each_with_index do |el, idx|
    next if el.is_a?(FilterLexer::LogicalOperator)
    operator = nil
    operator = tree[idx - 1] if idx > 0
    if el.is_a?(Array)
      ast = join_ast(ast, arel_table.grouping(cleaned_to_arel(arel_table, el)), operator)
    else
      ast = join_ast(ast, el.to_arel(arel_table), operator)
    end
  end

  return ast
end

.from_queryparams(klass, queryparams) ⇒ Object 



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# File 'lib/queryfy.rb', line 103

def self.from_queryparams(klass, queryparams)
  filter = ''
  offset = 0
  limit = Queryfy::default_limit
  if (queryparams.is_a?(Hash))
    filter = queryparams['filter'] unless queryparams['filter'].nil?
    offset = queryparams['offset'] unless queryparams['offset'].nil?
    limit = queryparams['limit'] unless queryparams['limit'].nil?
  elsif(queryparams.is_a?(String))
    filter = queryparams
  end
  return Queryfy.build_query(klass, filter, limit, offset)
end

.join_ast(ast, nodes, operator) ⇒ Object

Merges an existing ast with the passed nodes and uses the operator as a merge operator



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# File 'lib/queryfy.rb', line 91

def self.join_ast(ast, nodes, operator)
  if ast.nil? && !operator.nil?
    raise InvalidFilterFormat, "Cannot join on nil tree with operator near #{operator.text_value}"
  end
  if operator.nil? || ast.nil?
    ast = nodes
  else
    ast = ast.send(operator.to_arel, nodes)
  end
  return ast
end