Submodule box.tuple

The box.tuple submodule provides read-only access for the tuple userdata type. It allows, for a single tuple: selective retrieval of the field contents, retrieval of information about size, iteration over all the fields, and conversion to a Lua table.

Below is a list of all box.tuple functions.

This function will illustrate how to convert tuples to/from Lua tables and lists of scalars:

 
tuple = box.tuple.new({scalar1, scalar2, ... scalar_n}) -- scalars to tuplelua_table = {tuple:unpack()}                            -- tuple to Lua tablelua_table = tuple:totable()                             -- tuple to Lua tablescalar1, scalar2, ... scalar_n = tuple:unpack()         -- tuple to scalarstuple = box.tuple.new(lua_table)                        -- Lua table to tuple

Then it will find the field that contains 'b', remove that field from the tuple, and display how many bytes remain in the tuple. The function uses Tarantool box.tuple functions new(), unpack(), find(), transform(), bsize().

 
function example()  local tuple1, tuple2, lua_table_1, scalar1, scalar2, scalar3, field_number  local luatable1 = {}  tuple1 = box.tuple.new({'a', 'b', 'c'})  luatable1 = tuple1:totable()  scalar1, scalar2, scalar3 = tuple1:unpack()  tuple2 = box.tuple.new(luatable1[1],luatable1[2],luatable1[3])  field_number = tuple2:find('b')  tuple2 = tuple2:transform(field_number, 1)  return 'tuple2 = ' , tuple2 , ' # of bytes = ' , tuple2:bsize()end

... And here is what happens when one invokes the function:

 
tarantool> example()---- tuple2 =- ['a', 'c']- ' # of bytes = '- 5...