Class: Qdsl::Select

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

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(column_set) ⇒ Select

Returns a new instance of Select.



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# File 'lib/select.rb', line 5

def initialize(column_set)
  @column_set = column_set
  @inner_joins = []
end

Instance Attribute Details

#source ⇒ Object (readonly)

Returns the value of attribute source.



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# File 'lib/select.rb', line 3

def source
  @source
end

Instance Method Details

#add_inner_join(source, predicate_block) ⇒ Object 



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# File 'lib/select.rb', line 38

def add_inner_join(source, predicate_block)
  @inner_joins << InnerJoin.new(source, predicate_block)
  self
end

#create_query ⇒ Object 



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# File 'lib/select.rb', line 34

def create_query
  SelectQuery.new(self, @column_set)
end

#from(source) ⇒ Object 



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# File 'lib/select.rb', line 10

def from(source)
  @source = source
  self
end

#inner_join(source) ⇒ Object 



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# File 'lib/select.rb', line 30

def inner_join(source)
  InnerJoinBuilder.new(self, source)
end

#limit(count) ⇒ Object 



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# File 'lib/select.rb', line 25

def limit(count)
  @count = count
  self
end

#order_by(*columns, &block) ⇒ Object 



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# File 'lib/select.rb', line 20

def order_by(*columns, &block)
  @order_by_column_set = ColumnSet.new(columns, block)
  self
end

#render(context = nil, depth = 0, id = nil) ⇒ Object 



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# File 'lib/select.rb', line 43

def render(context = nil, depth = 0, id = nil)
  raise 'No FROM clause was specified' unless @source

  indent = '  ' * depth

  context ||= Context.new

  parameters = {}

  source_query = @source.create_query
  source_query_id = context.create_id
  source_result = source_query.render(context, depth + 1, source_query_id)

  inner_join_fragments = []
  inner_join_results = []
  @inner_joins.each do |inner_join|
    inner_join_query = inner_join.source.create_query
    inner_join_query_id = context.create_id
    inner_join_result = inner_join_query.render(context, depth + 1, inner_join_query_id)
    inner_join_results << inner_join_result
    x = ColumnProxy.new(source_result)
    y = ColumnProxy.new(inner_join_result)
    predicate = inner_join.predicate_block.call(x, y)

    # Should just use id attribute instead of passing dictionary!
    bah = {
      source_result => source_result.id,
      inner_join_result => inner_join_result.id,
    }

    predicate_result = predicate.render_sql(context, bah)

    inner_join_fragments << "#{indent}INNER JOIN #{inner_join_result.sql}"
    inner_join_fragments << "#{indent}ON #{predicate_result.sql}\n"
  end

  columns = @column_set.capture(source_result, inner_join_results)

  column_results = columns.collect { |x| x.render_sql(context, x.source.id) }

  fragments = []

  fragments << "#{indent}SELECT\n"
  column_results.each_with_index do |column_result, index|
    fragments << "#{indent}  #{column_result.sql}#{index < column_results.size - 1 ? ',' : ''}\n"
  end

  fragments << "#{indent}FROM #{source_result.sql}"

  fragments += inner_join_fragments

  if @where_predicate_block
    blah = [source_result] + inner_join_results
    proxies = blah.collect { |x| ColumnProxy.new(x) }
    where_predicate = @where_predicate_block.call(Util::fix_block_params(proxies))

    # Should just use id attribute instead of passing dictionary!
    bah = blah.inject({}) { |acc, x| acc[x] = x.id; acc }

    where_predicate_result = where_predicate.render_sql(context, bah)
    parameters.merge!(where_predicate_result.parameters)

    fragments << "#{indent}WHERE #{where_predicate_result.sql}\n"
  end

  if @order_by_column_set
    order_by_columns = @order_by_column_set.capture(source_result, inner_join_results)
    order_by_column_results = order_by_columns.collect { |x| x.render_sql(context, x.source.id) }
    fragments << "#{indent}ORDER BY #{order_by_column_results.collect(&:sql).join(', ')}\n"
  end

  if @count
    fragments << "LIMIT #{@count}"
  end

  sql = fragments.join
  RenderResult.new(
    id,
    sql,
    columns.collect(&:name),
    parameters
  )
end

#where(&predicate_block) ⇒ Object 



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# File 'lib/select.rb', line 15

def where(&predicate_block)
  @where_predicate_block = predicate_block
  self
end