Remove 1:1* connection, change 1:1 behaviour

Changes in 1:1 connection behaviour:

* The case when all connection parts are null is allowed (gives null
  child object instead of an error).
* The case when no child object were matched is allowed.
  - FULL MATCH contraint does not verified entirely (further work is
    needed).
  - The following bug was fixed: usage of filtering arguments now cannot
    trigger 'expect one matching object' error if data are consistent.

Other changes:

* GraphQL auto configuration behaviour was changed in case when a
  connection parts count is the same with underlying index, the index is
  unique and some index parts are nullable and some are not. Now it
  generates 1:1 connection (and lean on runtime checks) instead of
  giving an error.

Part of #135.

Author: Totktonada

graphql/accessor_general.lua

@@ -883,8 +883,7 @@ local function process_tuple(self, state, tuple, opts)
         if obj[k] == nil then
             local field_name = k
             local sub_filter = v
-            local sub_opts = {dont_force_nullability = true}
-            local field = resolveField(field_name, obj, sub_filter, sub_opts)
+            local field = resolveField(field_name, obj, sub_filter)
             if field == nil then return true end
             obj[k] = field
             -- XXX: Remove the value from a filter? But then we need to copy

graphql/config_complement.lua

@@ -9,64 +9,25 @@
 local json = require('json')
 local yaml = require('yaml')
 local log = require('log')
+
 local utils = require('graphql.utils')
 local check = utils.check
-local get_spaces_formats = require('graphql.simple_config').get_spaces_formats
 
 local config_complement = {}
 
---- The function determines connection type by connection.parts
---- and source collection space format.
----
---- XXX Currently there are two possible situations when connection_parts form
---- unique index - all source_fields are nullable (1:1*) or all source_fields
---- are non nullable (1:1). In case of partially nullable connection_parts (which
---- form unique index) the error is raised. There is an alternative: relax
---- this requirement and deduce non-null connection type in the case.
-local function determine_connection_type(connection_parts, index, source_space_format)
-    local type
-
-    if #connection_parts < #(index.fields) then
-        type = '1:N'
-    end
-
-    if #connection_parts == #(index.fields) then
-        if index.unique then
-            type = '1:1'
-        else
-            type = '1:N'
-        end
-    end
-
-    local is_all_nullable = true
-    local is_all_not_nullable = true
-
-    for _, connection_part in pairs(connection_parts) do
-        for _,field_format in ipairs(source_space_format) do
-            if connection_part.source_field == field_format.name then
-                if field_format.is_nullable == true then
-                    is_all_not_nullable = false
-                else
-                    is_all_nullable = false
-                end
-            end
-        end
-    end
-
-    if is_all_nullable == is_all_not_nullable and type == '1:1' then
-        error('source_fields in connection_parts must be all nullable or ' ..
-            'not nullable at the same time')
+--- Determine connection type by connection.parts and index uniqueness.
+local function determine_connection_type(connection_parts, index)
+    if #connection_parts < #index.fields then
+        return '1:N'
+    elseif #connection_parts == #index.fields then
+        return index.unique and '1:1' or '1:N'
     end
 
-    if is_all_nullable and type == '1:1' then
-        type = '1:1*'
-    end
-
-    return type
+    error(('Connection parts count is more then index parts count: %d > %d')
+        :format(#connection_parts, #index.fields))
 end
 
--- The function returns connection_parts sorted by destination_fields as
--- index_fields prefix.
+-- Return connection_parts sorted by destination_fields as index_fields prefix.
 local function sort_parts(connection_parts, index_fields)
     local sorted_parts = {}
 
@@ -211,8 +172,6 @@ local function complement_connections(collections, connections, indexes)
     check(collections, 'collections', 'table')
     check(connections, 'connections', 'table')
 
-    local spaces_formats = get_spaces_formats()
-
     for _, c in pairs(connections) do
         check(c.name, 'connection.name', 'string')
         check(c.source_collection, 'connection.source_collection', 'string')
@@ -230,10 +189,7 @@ local function complement_connections(collections, connections, indexes)
         result_c.destination_collection = c.destination_collection
         result_c.parts = determine_connection_parts(c.parts, index)
 
-        local source_space_format = spaces_formats[result_c.source_collection]
-
-        result_c.type = determine_connection_type(result_c.parts, index,
-            source_space_format)
+        result_c.type = determine_connection_type(result_c.parts, index)
         result_c.index_name = c.index_name
         result_c.name = c.name
 

graphql/convert_schema/resolve.lua

@@ -106,29 +106,16 @@ function resolve.gen_resolve_function(collection_name, connection,
         local opts = opts or {}
         assert(type(opts) == 'table',
             'opts must be nil or a table, got ' .. type(opts))
-        local dont_force_nullability =
-            opts.dont_force_nullability or false
-        assert(type(dont_force_nullability) == 'boolean',
-            'opts.dont_force_nullability ' ..
-            'must be nil or a boolean, got ' ..
-            type(dont_force_nullability))
+        -- no opts for now
 
         local from = gen_from_parameter(collection_name, parent, c)
 
         -- Avoid non-needed index lookup on a destination collection when
         -- all connection parts are null:
-        -- * return null for 1:1* connection;
+        -- * return null for 1:1 connection;
         -- * return {} for 1:N connection (except the case when source
         --   collection is the query or the mutation pseudo-collection).
         if collection_name ~= nil and are_all_parts_null(parent, c.parts) then
-            if c.type ~= '1:1*' and c.type ~= '1:N' then
-                -- `if` is to avoid extra json.encode
-                assert(c.type == '1:1*' or c.type == '1:N',
-                    ('only 1:1* or 1:N connections can have ' ..
-                    'all key parts null; parent is %s from ' ..
-                    'collection "%s"'):format(json.encode(parent),
-                        tostring(collection_name)))
-            end
             return c.type == '1:N' and {} or nil
         end
 
@@ -152,14 +139,8 @@ function resolve.gen_resolve_function(collection_name, connection,
         assert(type(objs) == 'table',
             'objs list received from an accessor ' ..
             'must be a table, got ' .. type(objs))
-        if c.type == '1:1' or c.type == '1:1*' then
-            -- we expect here exactly one object even for 1:1*
-            -- connections because we processed all-parts-are-null
-            -- situation above
-            assert(#objs == 1 or dont_force_nullability,
-                'expect one matching object, got ' ..
-                tostring(#objs))
-            return objs[1]
+        if c.type == '1:1' then
+            return objs[1] -- nil for empty list of matching objects
         else -- c.type == '1:N'
             return objs
         end

graphql/convert_schema/schema.lua

@@ -25,7 +25,7 @@ local schema = {}
 --- * DONE: Move avro-schema -> GraphQL arguments translating into its own
 ---   module.
 --- * DONE: Support a sub-record arguments and others (union, array, ...).
---- * TBD: Generate arguments for cartesian product of {1:1, 1:1*, 1:N, all} x
+--- * TBD: Generate arguments for cartesian product of {1:1, 1:N, all} x
 ---   {query, mutation, all} x {top-level, nested, all} x {collections}.
 --- * TBD: Use generated arguments in GraphQL types (schema) generation.
 ---
@@ -138,7 +138,8 @@ local function create_root_collection(state)
     })
 end
 
---- Execute a function for each 1:1 or 1:1* connection of each collection.
+--- Execute a function for each connection of one of specified types in each
+--- collection.
 ---
 --- @tparam table state tarantool_graphql instance
 ---
@@ -160,7 +161,7 @@ local function for_each_connection(state, connection_types, func)
     end
 end
 
---- Add arguments corresponding to 1:1 and 1:1* connections (nested filters).
+--- Add arguments corresponding to 1:1 connections (nested filters).
 ---
 --- @tparam table state graphql_tarantool instance
 local function add_connection_arguments(state)
@@ -169,8 +170,8 @@ local function add_connection_arguments(state)
     -- map source collection and connection name to an input object
     local lookup_input_objects = {}
 
-    -- create InputObjects for each 1:1 or 1:1* connection of each collection
-    for_each_connection(state, {'1:1', '1:1*'}, function(collection_name, c)
+    -- create InputObjects for each 1:1 connection of each collection
+    for_each_connection(state, {'1:1'}, function(collection_name, c)
         -- XXX: support multihead connections
         if c.variants ~= nil then return end
 
@@ -195,7 +196,7 @@ local function add_connection_arguments(state)
 
     -- update fields of collection arguments and input objects with other input
     -- objects
-    for_each_connection(state, {'1:1', '1:1*'}, function(collection_name, c)
+    for_each_connection(state, {'1:1'}, function(collection_name, c)
         -- XXX: support multihead connections
         if c.variants ~= nil then return end
 

graphql/convert_schema/types.lua

@@ -49,8 +49,6 @@ local function args_from_destination_collection(state, collection,
                                                 connection_type)
     if connection_type == '1:1' then
         return state.object_arguments[collection]
-    elseif connection_type == '1:1*' then
-        return state.object_arguments[collection]
     elseif connection_type == '1:N' then
         return state.all_arguments[collection]
     else
@@ -60,8 +58,6 @@ end
 
 local function specify_destination_type(destination_type, connection_type)
     if connection_type == '1:1' then
-        return core_types.nonNull(destination_type)
-    elseif connection_type == '1:1*' then
         return destination_type
     elseif connection_type == '1:N' then
         return core_types.nonNull(core_types.list(core_types.nonNull(
@@ -77,7 +73,7 @@ end
 --- described in comments to @{convert_multihead_connection}.
 ---
 --- @tparam table type_to_box GraphQL Object type (which represents a collection)
---- @tparam string connection_type of given collection (1:1, 1:1* or 1:N)
+--- @tparam string connection_type of given collection (1:1, 1:N)
 --- @tparam string type_to_box_name name of given 'type_to_box' (It can not
 --- be taken from 'type_to_box' because at the time of function execution
 --- 'type_to_box' refers to an empty table, which later will be filled with
@@ -96,9 +92,6 @@ local function box_collection_type(type_to_box, connection_type,
     if connection_type == '1:1' then
         box_type_name = 'box_' .. type_to_box_name
         box_type_description = 'Box around 1:1 multi-head variant'
-    elseif connection_type == '1:1*' then
-        box_type_name = 'box_' .. type_to_box_name
-        box_type_description = 'Box around 1:1* multi-head variant'
     elseif connection_type == '1:N' then
         box_type_name = 'box_array_' .. type_to_box_name
         box_type_description = 'Box around 1:N multi-head variant'
@@ -317,9 +310,8 @@ end
 local convert_connection_to_field = function(state, connection, collection_name,
         context)
     check(connection.type, 'connection.type', 'string')
-    assert(connection.type == '1:1' or connection.type == '1:1*' or
-        connection.type == '1:N', 'connection.type must be 1:1, 1:1* or 1:N, '..
-        'got ' .. connection.type)
+    assert(connection.type == '1:1' or connection.type == '1:N',
+        'connection.type must be 1:1 or 1:N, got ' .. connection.type)
     check(connection.name, 'connection.name', 'string')
     assert(connection.destination_collection or connection.variants,
         'connection must either destination_collection or variants field')

graphql/impl.lua

@@ -244,7 +244,7 @@ end
 ---                 --   any query-related data;
 ---                 -- * `resolveField(field_name, object, filter, opts)`
 ---                 --   (function) for performing a subrequest on a fields
----                 --   connected using a 1:1 or 1:1* connection.
+---                 --   connected using a 1:1 connection.
 ---                 --
 ---                 return ...
 ---             end,

test/extra/to_avro_huge.test.lua

@@ -114,7 +114,7 @@ fields:
                     type: int
                   - name: order_item__item
                     type:
-                      type: record
+                      type: record*
                       fields:
                       - name: id
                         type: int
@@ -144,7 +144,7 @@ fields:
         type: string
       - name: user_connection
         type:
-          type: record
+          type: record*
           fields:
           - name: id
             type: int
@@ -168,7 +168,7 @@ fields:
                       fields:
                       - name: order_item__item
                         type:
-                          type: record
+                          type: record*
                           fields:
                           - name: name
                             type: string

test/testdata/nullable_1_1_conn_testdata.lua

@@ -51,7 +51,7 @@ function nullable_1_1_conn_testdata.get_test_metadata()
                     "index_name": "in_reply_to"
                 },
                 {
-                    "type": "1:1*",
+                    "type": "1:1",
                     "name": "in_reply_to",
                     "destination_collection": "email",
                     "parts": [