Postgres adapter: Allow source fields in json_extract_path (#660)

Author: greg-rychlewski

integration_test/myxql/test_helper.exs

@@ -119,7 +119,9 @@ excludes = [
   # MySQL doesn't support specifying columns for ON DELETE SET NULL
   :on_delete_nilify_column_list,
   # MySQL doesnt' support anything except a single column in DISTINCT
-  :multicolumn_distinct
+  :multicolumn_distinct,
+  # uncertain whether we can support this. needs more exploring
+  :json_extract_path_with_field
 ]
 
 if Version.match?(version, ">= 8.0.0") do

integration_test/support/migration.exs

@@ -89,6 +89,7 @@ defmodule Ecto.Integration.Migration do
     end
 
     create table(:orders) do
+      add :label, :string
       add :item, :map
       add :items, :map
       add :meta, :map

lib/ecto/adapters/myxql/connection.ex

@@ -812,6 +812,12 @@ if Code.ensure_loaded?(MyXQL) do
 
           integer when is_integer(integer) ->
             "[#{integer}]"
+
+          _ ->
+            error!(
+              query,
+              "MySQL adapter does not support references to source fields inside of `json_extract_path`"
+            )
         end)
 
       ["json_extract(", expr(expr, sources, query), ", '$", path, "')"]

lib/ecto/adapters/postgres/connection.ex

@@ -1141,8 +1141,8 @@ if Code.ensure_loaded?(Postgrex) do
     end
 
     defp json_extract_path(expr, path, sources, query) do
-      path = Enum.map_intersperse(path, ?,, &escape_json/1)
-      [?(, expr(expr, sources, query), "#>'{", path, "}')"]
+      path = Enum.map_intersperse(path, ?,, &escape_json(&1, sources, query))
+      [?(, expr(expr, sources, query), "#>array[", path, "]::text[])"]
     end
 
     defp values_list(types, idx, num_rows) do
@@ -2022,6 +2022,26 @@ if Code.ensure_loaded?(Postgrex) do
     defp escape_json(true), do: ["true"]
     defp escape_json(false), do: ["false"]
 
+    # To allow columns in json paths, we use the array[...] syntax
+    # which requires special handling for strings and column references.
+    # We still keep the escape_json/1 variant for strings because it is
+    # needed for the queries using @>
+    defp escape_json(value, _, _) when is_binary(value) do
+      [?', escape_string(value), ?']
+    end
+
+    defp escape_json({{:., _, [{:&, _, [_]}, _]}, _, []} = expr, sources, query) do
+      expr(expr, sources, query)
+    end
+
+    defp escape_json({{:., _, [{:parent_as, _, [_]}, _]}, _, []} = expr, sources, query) do
+      expr(expr, sources, query)
+    end
+
+    defp escape_json(other, _, _) do
+      escape_json(other)
+    end
+
     defp ecto_to_db({:array, t}), do: [ecto_to_db(t), ?[, ?]]
     defp ecto_to_db(:id), do: "integer"
     defp ecto_to_db(:identity), do: "bigint"

mix.lock

@@ -4,7 +4,7 @@
   "decimal": {:hex, :decimal, "2.3.0", "3ad6255aa77b4a3c4f818171b12d237500e63525c2fd056699967a3e7ea20f62", [:mix], [], "hexpm", "a4d66355cb29cb47c3cf30e71329e58361cfcb37c34235ef3bf1d7bf3773aeac"},
   "deep_merge": {:hex, :deep_merge, "1.0.0", "b4aa1a0d1acac393bdf38b2291af38cb1d4a52806cf7a4906f718e1feb5ee961", [:mix], [], "hexpm", "ce708e5f094b9cd4e8f2be4f00d2f4250c4095be93f8cd6d018c753894885430"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.41", "ab34711c9dc6212dda44fcd20ecb87ac3f3fce6f0ca2f28d4a00e4154f8cd599", [:mix], [], "hexpm", "a81a04c7e34b6617c2792e291b5a2e57ab316365c2644ddc553bb9ed863ebefa"},
-  "ecto": {:git, "https://github.com/elixir-ecto/ecto.git", "b02e921b7d2a2a4d5a73fe0ead6500a6bec9d207", []},
+  "ecto": {:git, "https://github.com/elixir-ecto/ecto.git", "60120357088650119b6e1b0ee6277637bae943c1", []},
   "ex_doc": {:hex, :ex_doc, "0.34.2", "13eedf3844ccdce25cfd837b99bea9ad92c4e511233199440488d217c92571e8", [:mix], [{:earmark_parser, "~> 1.4.39", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_c, ">= 0.1.0", [hex: :makeup_c, repo: "hexpm", optional: true]}, {:makeup_elixir, "~> 0.14 or ~> 1.0", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1 or ~> 1.0", [hex: :makeup_erlang, repo: "hexpm", optional: false]}, {:makeup_html, ">= 0.1.0", [hex: :makeup_html, repo: "hexpm", optional: true]}], "hexpm", "5ce5f16b41208a50106afed3de6a2ed34f4acfd65715b82a0b84b49d995f95c1"},
   "jason": {:hex, :jason, "1.4.4", "b9226785a9aa77b6857ca22832cffa5d5011a667207eb2a0ad56adb5db443b8a", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "c5eb0cab91f094599f94d55bc63409236a8ec69a21a67814529e8d5f6cc90b3b"},
   "makeup": {:hex, :makeup, "1.1.2", "9ba8837913bdf757787e71c1581c21f9d2455f4dd04cfca785c70bbfff1a76a3", [:mix], [{:nimble_parsec, "~> 1.2.2 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "cce1566b81fbcbd21eca8ffe808f33b221f9eee2cbc7a1706fc3da9ff18e6cac"},

test/ecto/adapters/postgres_test.exs

@@ -963,16 +963,36 @@ defmodule Ecto.Adapters.PostgresTest do
 
   test "json_extract_path" do
     query = Schema |> select([s], json_extract_path(s.meta, [0, 1])) |> plan()
-    assert all(query) == ~s|SELECT (s0.\"meta\"#>'{0,1}') FROM "schema" AS s0|
+    assert all(query) == ~s|SELECT (s0.\"meta\"#>array[0,1]::text[]) FROM "schema" AS s0|
 
     query = Schema |> select([s], json_extract_path(s.meta, ["a", "b"])) |> plan()
-    assert all(query) == ~s|SELECT (s0.\"meta\"#>'{"a","b"}') FROM "schema" AS s0|
+    assert all(query) == ~s|SELECT (s0.\"meta\"#>array['a','b']::text[]) FROM "schema" AS s0|
 
     query = Schema |> select([s], json_extract_path(s.meta, ["'a"])) |> plan()
-    assert all(query) == ~s|SELECT (s0.\"meta\"#>'{"''a"}') FROM "schema" AS s0|
+    assert all(query) == ~s|SELECT (s0.\"meta\"#>array['''a']::text[]) FROM "schema" AS s0|
 
     query = Schema |> select([s], json_extract_path(s.meta, ["\"a"])) |> plan()
-    assert all(query) == ~s|SELECT (s0.\"meta\"#>'{"\\"a"}') FROM "schema" AS s0|
+    assert all(query) == ~s|SELECT (s0.\"meta\"#>array['\"a']::text[]) FROM "schema" AS s0|
+
+    query = Schema |> select([s], json_extract_path(s.meta, [s.x])) |> plan()
+    assert all(query) == ~s|SELECT (s0.\"meta\"#>array[s0.\"x\"]::text[]) FROM "schema" AS s0|
+
+    query = Schema |> select([s], json_extract_path(s.meta, ["a", s.x, 0])) |> plan()
+
+    assert all(query) ==
+             ~s|SELECT (s0.\"meta\"#>array['a',s0.\"x\",0]::text[]) FROM "schema" AS s0|
+
+    squery =
+      Schema
+      |> where([s], is_nil(json_extract_path(s.meta, [parent_as(:s).x])))
+      |> select([s], s.x)
+
+    query =
+      Schema |> from(as: :s) |> where([s], s.x in subquery(squery)) |> select([s], s.x) |> plan()
+
+    assert all(query) ==
+             ~s|SELECT s0.\"x\" FROM "schema" AS s0 WHERE (s0.\"x\" IN | <>
+               ~s|(SELECT ss0.\"x\" FROM \"schema\" AS ss0 WHERE ((ss0.\"meta\"#>array[s0.\"x\"]::text[]) IS NULL)))|
   end
 
   test "optimized json_extract_path" do
@@ -985,10 +1005,12 @@ defmodule Ecto.Adapters.PostgresTest do
     query = Schema |> where([s], s.meta["tags"][0]["name"] == "123") |> select(true) |> plan()
 
     assert all(query) ==
-             ~s|SELECT TRUE FROM "schema" AS s0 WHERE (((s0."meta"#>'{"tags",0}')@>'{"name": "123"}'))|
+             ~s|SELECT TRUE FROM "schema" AS s0 WHERE (((s0."meta"#>array['tags',0]::text[])@>'{"name": "123"}'))|
 
     query = Schema |> where([s], s.meta[0] == "123") |> select(true) |> plan()
-    assert all(query) == ~s|SELECT TRUE FROM "schema" AS s0 WHERE ((s0.\"meta\"#>'{0}') = '123')|
+
+    assert all(query) ==
+             ~s|SELECT TRUE FROM "schema" AS s0 WHERE ((s0.\"meta\"#>array[0]::text[]) = '123')|
 
     query = Schema |> where([s], s.meta["enabled"] == true) |> select(true) |> plan()
 
@@ -998,7 +1020,12 @@ defmodule Ecto.Adapters.PostgresTest do
     query = Schema |> where([s], s.meta["extra"][0]["enabled"] == false) |> select(true) |> plan()
 
     assert all(query) ==
-             ~s|SELECT TRUE FROM "schema" AS s0 WHERE (((s0."meta"#>'{"extra",0}')@>'{"enabled": false}'))|
+             ~s|SELECT TRUE FROM "schema" AS s0 WHERE (((s0."meta"#>array['extra',0]::text[])@>'{"enabled": false}'))|
+
+    query = Schema |> where([s], s.meta[s.x][0]["name"] == "123") |> select(true) |> plan()
+
+    assert all(query) ==
+             ~s|SELECT TRUE FROM "schema" AS s0 WHERE (((s0."meta"#>array[s0.\"x\",0]::text[])@>'{"name": "123"}'))|
   end
 
   test "nested expressions" do