From 2022492f21ca65bd0eb7e73adb96648784bf2bd8 Mon Sep 17 00:00:00 2001
From: Michael Hoennig <michael@hoennig.de>
Date: Tue, 23 Aug 2022 09:36:39 +0200
Subject: [PATCH] implements jsonb-changes-delta
---
.../db/changelog/004-jsonb-changes-delta.sql | 134 ++++++++++++++++++
.../db/changelog/db.changelog-master.yaml | 2 +
2 files changed, 136 insertions(+)
create mode 100644 src/main/resources/db/changelog/004-jsonb-changes-delta.sql
diff --git a/src/main/resources/db/changelog/004-jsonb-changes-delta.sql b/src/main/resources/db/changelog/004-jsonb-changes-delta.sql
new file mode 100644
index 00000000..04ef1c18
--- /dev/null
+++ b/src/main/resources/db/changelog/004-jsonb-changes-delta.sql
@@ -0,0 +1,134 @@
+--liquibase formatted sql
+
+
+-- ============================================================================
+--changeset JSONB-CHANGES-DELTA:1 endDelimiter:--//
+-- ----------------------------------------------------------------------------
+/*
+ Recursively compares two jsonb values and returns what has changed.
+ This is a kind of right sided json diff.
+ */
+
+create or replace function jsonb_changes_delta(oldJson jsonb, newJson jsonb)
+ returns jsonb
+ called on null input
+ language plpgsql as $$
+declare
+ diffJson jsonb;
+ oldJsonElement record;
+begin
+ raise notice '>>> diffing: % % vs. % %', jsonb_typeof(oldJson), oldJson, jsonb_typeof(newJson), newJson;
+
+ if oldJson is null or jsonb_typeof(oldJson) = 'null' or
+ newJson is null or jsonb_typeof(newJson) = 'null' then
+ return newJson;
+ end if;
+
+ diffJson = newJson;
+ for oldJsonElement in select * from jsonb_each(oldJson)
+ loop
+ raise notice 'intermediate result: %', diffJson;
+ raise notice 'record: %', oldJsonElement;
+ if diffJson @> jsonb_build_object(oldJsonElement.key, oldJsonElement.value) then
+ raise notice 'ignoring equal: %', oldJsonElement.key;
+ diffJson = diffJson - oldJsonElement.key;
+ elsif diffJson ? oldJsonElement.key then
+ if jsonb_typeof(newJson -> (oldJsonElement.key)) = 'object' then
+ raise notice 'diffing new: % -> %', oldJsonElement.key, newJson -> (oldJsonElement.key);
+ diffJson = diffJson ||
+ jsonb_build_object(oldJsonElement.key,
+ jsonb_changes_delta(oldJsonElement.value, newJson -> (oldJsonElement.key)));
+ else
+ raise notice 'not an object: %, leaving %', oldJsonElement.key, newJson -> (oldJsonElement.key);
+ end if;
+ continue;
+ else
+ raise notice 'nulling old: %', oldJsonElement.key;
+ diffJson = diffJson || jsonb_build_object(oldJsonElement.key, null);
+ end if;
+ end loop;
+ raise notice '<<< result: %', diffJson;
+ return diffJson;
+end; $$;
+
+/*
+ Tests jsonb_diff.
+ */
+do language plpgsql $$
+ declare
+ expected text;
+ actual text;
+ begin
+
+ select jsonb_changes_delta(null::jsonb, null::jsonb) into actual;
+ if actual is not null then
+ raise exception 'jsonb_diff #1 failed:% expected: %,% actually: %', E'\n', expected, E'\n', actual;
+ end if;
+
+ select jsonb_changes_delta(null::jsonb, '{"a": "new"}'::jsonb) into actual;
+ expected := '{"a": "new"}'::jsonb;
+ if actual <> expected then
+ raise exception 'jsonb_diff #2 failed:% expected: %,% actual: %', E'\n', expected, E'\n', actual;
+ end if;
+
+ select jsonb_changes_delta('{"a": "old"}'::jsonb, '{"a": "new"}'::jsonb) into actual;
+ expected := '{"a": "new"}'::jsonb;
+ if actual <> expected then
+ raise exception 'jsonb_diff #3 failed:% expected: %,% actual: %', E'\n', expected, E'\n', actual;
+ end if;
+
+ select jsonb_changes_delta('{"a": "old"}'::jsonb, '{"a": "old"}'::jsonb) into actual;
+ expected := '{}'::jsonb;
+ if actual <> expected then
+ raise exception 'jsonb_diff #4 failed:% expected: %,% actual: %', E'\n', expected, E'\n', actual;
+ end if;
+
+ select jsonb_changes_delta(
+ $json${
+ "a": "same",
+ "b": "old",
+ "c": "set",
+ "d": "set",
+ "e": null,
+ "i": {
+ "x": "equal",
+ "y": "old",
+ "z": "old"
+ },
+ "j": {
+ "k": "set"
+ },
+ "l": {
+ "m": "equal",
+ "n": null
+ }
+ }$json$::jsonb,
+ $json${
+ "a": "same",
+ "b": "new",
+ "c": null,
+ "e": {
+ "f": "set"
+ },
+ "g": "set",
+ "i": {
+ "x": "equal",
+ "y": "new",
+ "z": null
+ },
+ "j": null,
+ "l": {
+ "m": "equal",
+ "n": null
+ }
+ }$json$::jsonb
+ )
+ into actual;
+ expected :=
+ $json${"b": "new", "c": null, "d": null, "e": {"f": "set"}, "g": "set", "i": {"y": "new", "z": null}, "j": null}$json$;
+ if actual <> expected then
+ raise exception 'jsonb_diff #5 failed:% expected: %,% actual: %', E'\n', expected, E'\n', actual;
+ end if;
+ end; $$;
+--//
+
diff --git a/src/main/resources/db/changelog/db.changelog-master.yaml b/src/main/resources/db/changelog/db.changelog-master.yaml
index c7175eb0..929a6f33 100644
--- a/src/main/resources/db/changelog/db.changelog-master.yaml
+++ b/src/main/resources/db/changelog/db.changelog-master.yaml
@@ -5,6 +5,8 @@ databaseChangeLog:
file: db/changelog/002-int-to-var.sql
- include:
file: db/changelog/003-random-in-range.sql
+ - include:
+ file: db/changelog/004-jsonb-changes-delta.sql
- include:
file: db/changelog/005-uuid-ossp-extension.sql
- include: