WIP: Integrate expressions into GraphQL

Part of #13.

Author: Totktonada

graphql/core/rules.lua

@@ -604,4 +604,43 @@ end
 
 -- }}}
 
+-- {{{ compile filter argument
+
+function rules.compileFilterArgument(node, context)
+  local expressions = require('expressions') -- XXX: move upward
+
+  assert(node.kind == 'argument')
+  local name = node.name.value
+
+  -- XXX: 1:1-connected object can have field 'filter'
+  if name ~= 'filter' then return end
+
+  -- save compiled expression
+  local value = node.value
+  assert(type(value) == 'string') -- XXX: better error
+  node.compiled = expressions.new(value)
+
+  -- XXX: don't blindly find the pattern {kind = 'variable', ...}, but either
+  -- traverse a tree according to node kinds or export used variables info from
+  -- expressions module
+
+  -- mark used variables
+  local open_set = {node.compiled}
+  while true do
+    local e_node = table.remove(open_set, 1)
+    if e_node == nil then break end
+    if type(e_node) == 'table' then
+      if e_node.kind == 'variable' then
+        context.variableReferences[e_node.name] = true
+      else
+        for _, child_e_node in pairs(e_node) do
+          table.insert(open_set, child_e_node)
+        end
+      end
+    end
+  end
+end
+
+-- }}}
+
 return rules

graphql/core/validate.lua

@@ -265,7 +265,10 @@ local visitors = {
         end)
     end,
 
-    rules = { rules.uniqueInputObjectFields }
+    rules = {
+      rules.uniqueInputObjectFields,
+      rules.compileFilterArgument,
+    }
   },
 
   inputObject = {

graphql/gen_arguments.lua

@@ -348,7 +348,7 @@ function gen_arguments.list_args(db_schema, collection_name)
     return {
         {name = 'limit', type = 'int*'},
         {name = 'offset', type = offset_type},
-        -- {name = 'filter', type = ...},
+        {name = 'filter', type = 'string*'},
         pcre_field,
     }
 end

test/common/expressions.test.lua

@@ -0,0 +1,149 @@
+#!/usr/bin/env tarantool
+
+-- https://github.com/tarantool/graphql/issues/13
+
+local fio = require('fio')
+
+-- require in-repo version of graphql/ sources despite current working directory
+package.path = fio.abspath(debug.getinfo(1).source:match("@?(.*/)")
+    :gsub('/./', '/'):gsub('/+$', '')) .. '/../../?.lua' .. ';' .. package.path
+
+local tap = require('tap')
+local yaml = require('yaml')
+local test_utils = require('test.test_utils')
+local testdata = require('test.testdata.common_testdata')
+
+local function run_queries(gql_wrapper)
+    local test = tap.test('expressions')
+    test:plan(3)
+
+    local exp_result_1_and_2 = test_utils.deeply_number_tostring(yaml.decode(([[
+        ---
+        order_collection:
+        - order_id: order_id_4
+          price: 4.3333333333333
+        - order_id: order_id_5
+          price: 4.6666666666667
+    ]]):strip()))
+
+    -- {{{ test expresion (use variables and &&)
+
+    local query_1 = [[
+        query get_by_expr($order_id_from: Double, $order_id_to: Double) {
+            order_collection(
+                filter: "order_id >= $order_id_from && order_id < $order_id_to"
+            ) {
+                order_id
+                price
+            }
+        }
+    ]]
+
+    local gql_query_1 = test_utils.show_trace(function()
+        return gql_wrapper:compile(query_1)
+    end)
+
+    local variables_1 = {
+        order_id_from = 4,
+        order_id_to = 5,
+    }
+
+    local result_1 = test_utils.show_trace(function()
+        return gql_query_1:execute(variables_1)
+    end)
+
+    local result_1_data = test_utils.deeply_number_tostring(result_1.data)
+    test:is_deeply(result_1_data, exp_result_1_and_2,
+        'expressions with variables and &&')
+
+    -- }}}
+
+    -- {{{ test expresion (use immediate values and &&)
+
+    local query_2 = [[
+        query get_by_expr {
+            order_collection(
+                filter: "order_id >= 4 && order_id < 5"
+            ) {
+                order_id
+                price
+            }
+        }
+    ]]
+
+    local gql_query_2 = test_utils.show_trace(function()
+        return gql_wrapper:compile(query_2)
+    end)
+
+    local variables_2 = {}
+
+    local result_2 = test_utils.show_trace(function()
+        return gql_query_2:execute(variables_2)
+    end)
+
+    local result_2_data = test_utils.deeply_number_tostring(result_2.data)
+    test:is_deeply(result_2_data, exp_result_1_and_2,
+        'expression with immediate values and &&')
+
+    -- }}}
+
+    -- {{{ test expression with nested fields and ||
+
+    local query_3 = [[
+        query get_by_expr {
+            order_metainfo_collection(
+                filter: "store.address.city == 1 || store.address.city == 42"
+            ) {
+                order_metainfo_id
+                store {
+                    address {
+                        city
+                    }
+                }
+            }
+        }
+    ]]
+
+    local gql_query_3 = test_utils.show_trace(function()
+        return gql_wrapper:compile(query_3)
+    end)
+
+    local exp_result_3 = test_utils.deeply_number_tostring(yaml.decode(([[
+        ---
+        order_metainfo_collection:
+        - order_metainfo_id: order_metainfo_id_1
+          store:
+            address:
+              city: city 1
+        - order_metainfo_id: order_metainfo_id_42
+          store:
+            address:
+              city: city 42
+    ]]):strip()))
+
+    local variables_3 = {}
+
+    local result_3 = test_utils.show_trace(function()
+        return gql_query_3:execute(variables_3)
+    end)
+
+    local result_3_data = test_utils.deeply_number_tostring(result_3.data)
+    test:is_deeply(result_3_data, exp_result_3,
+        'expression with nested fields and ||')
+
+    -- }}}
+
+    assert(test:check(), 'check plan')
+end
+
+box.cfg({})
+
+test_utils.run_testdata(testdata, {
+    run_queries = run_queries,
+    graphql_opts = {
+        -- gh-137: timeout exceeded
+        timeout_ms = 10000, -- 10 seconds
+    }
+})
+
+os.exit()