PostgreSQL比较两个jsonb对象
使用,格式提供了极好的机会。但现在我被一个看起来相对简单的操作困住了 比较两个jsonb对象;查看一个文档与另一个文档的不同之处或缺失之处 到目前为止我拥有的PostgreSQL比较两个jsonb对象,postgresql,jsonb,postgresql-9.5,Postgresql,Jsonb,Postgresql 9.5,使用,格式提供了极好的机会。但现在我被一个看起来相对简单的操作困住了 比较两个jsonb对象;查看一个文档与另一个文档的不同之处或缺失之处 到目前为止我拥有的 WITH reports(id,DATA) AS ( VALUES (1,'{"a":"aaa", "b":"bbb", "c":"ccc"}'::jsonb), (2,'{"a":"aaa", "b":"jjj", "d":"ddd"}'::jsonb) ) SELECT jsonb
WITH reports(id,DATA) AS (
VALUES (1,'{"a":"aaa", "b":"bbb", "c":"ccc"}'::jsonb),
(2,'{"a":"aaa", "b":"jjj", "d":"ddd"}'::jsonb) )
SELECT jsonb_object_agg(anon_1.key, anon_1.value)
FROM
(SELECT anon_2.key AS KEY,
reports.data -> anon_2.KEY AS value
FROM reports,
(SELECT DISTINCT jsonb_object_keys(reports.data) AS KEY
FROM reports) AS anon_2
ORDER BY reports.id DESC) AS anon_1
应返回第1行与第2行的差值:
'{"b":"bbb", "c":"ccc", "d":null}'
相反,它还返回重复项({“a”:“aaa”}
)。也;总的来说,可能有一种更优雅的方法 更新
查询:
SELECT jsonb_diff_val(
'{"a":"aaa", "b":"bbb", "c":"ccc"}'::jsonb,
'{"a":"aaa", "b":"jjj", "d":"ddd"}'::jsonb
);
jsonb_diff_val
---------------------------------------
{"b": "bbb", "c": "ccc", "d": "null"}
(1 row)
我创建了类似的函数,该函数将递归扫描对象,并返回新对象和旧对象之间的差异。我无法找到一种“更好”的方法来确定jsonb对象是否“为空”——因此,如果有任何建议可以简化它,我将不胜感激。我计划使用它来跟踪对jsonb对象的更新,所以我只存储已经更改的内容 以下是函数:
CREATE OR REPLACE FUNCTION jsonb_diff_val(val1 JSONB,val2 JSONB)
RETURNS JSONB AS $$
DECLARE
result JSONB;
object_result JSONB;
i int;
v RECORD;
BEGIN
IF jsonb_typeof(val1) = 'null'
THEN
RETURN val2;
END IF;
result = val1;
FOR v IN SELECT * FROM jsonb_each(val1) LOOP
result = result || jsonb_build_object(v.key, null);
END LOOP;
FOR v IN SELECT * FROM jsonb_each(val2) LOOP
IF jsonb_typeof(val1->v.key) = 'object' AND jsonb_typeof(val2->v.key) = 'object'
THEN
object_result = jsonb_diff_val(val1->v.key, val2->v.key);
-- check if result is not empty
i := (SELECT count(*) FROM jsonb_each(object_result));
IF i = 0
THEN
result = result - v.key; --if empty remove
ELSE
result = result || jsonb_build_object(v.key,object_result);
END IF;
ELSIF val1->v.key = val2->v.key THEN
result = result - v.key;
ELSE
result = result || jsonb_build_object(v.key,v.value);
END IF;
END LOOP;
RETURN result;
END;
$$ LANGUAGE plpgsql;
然后简单查询如下所示:
SELECT jsonb_diff_val(
'{"a":"aaa", "b":{"b1":"b","b2":"bb","b3":{"b3a":"aaa","b3c":"ccc"}}, "c":"ccc"}'::jsonb,
'{"a":"aaa", "b":{"b1":"b1","b3":{"b3a":"aaa","b3c":"cccc"}}, "d":"ddd"}'::jsonb
);
jsonb_diff_val
-------------------------------------------------------------------------------
{"b": {"b1": "b1", "b2": null, "b3": {"b3c": "cccc"}}, "c": null, "d": "ddd"}
(1 row)
SELECT * FROM jsonb_object_diff(
'{"a": 1, "b": 5, "extra1": "woo", "old_null": null, "just_null": null}'::jsonb,
'{"a": 1, "b": 4, "extra2": "ahoj", "new_null": null, "just_null": null}'::jsonb);
-[ RECORD 1 ]--------------------------------------
old | {"b": 5, "extra1": "woo", "old_null": null}
new | {"b": 4, "extra2": "ahoj", "new_null": null}
same | {"a": 1, "just_null": null}
我的解决方案不是递归的,但您可以使用它来检测公共键/值:
-- Diff two jsonb objects
CREATE TYPE jsonb_object_diff_result AS (
old jsonb,
new jsonb,
same jsonb
);
CREATE OR REPLACE FUNCTION jsonb_object_diff(in_old jsonb, in_new jsonb)
RETURNS jsonb_object_diff_result AS
$jsonb_object_diff$
DECLARE
_key text;
_value jsonb;
_old jsonb;
_new jsonb;
_same jsonb;
BEGIN
_old := in_old;
_new := in_new;
FOR _key, _value IN SELECT * FROM jsonb_each(_old) LOOP
IF (_new -> _key) = _value THEN
_old := _old - _key;
_new := _new - _key;
IF _same IS NULL THEN
_same := jsonb_build_object(_key, _value);
ELSE
_same := _same || jsonb_build_object(_key, _value);
END IF;
END IF;
END LOOP;
RETURN (_old, _new, _same);
END;
$jsonb_object_diff$
LANGUAGE plpgsql;
结果可以如下所示:
SELECT jsonb_diff_val(
'{"a":"aaa", "b":{"b1":"b","b2":"bb","b3":{"b3a":"aaa","b3c":"ccc"}}, "c":"ccc"}'::jsonb,
'{"a":"aaa", "b":{"b1":"b1","b3":{"b3a":"aaa","b3c":"cccc"}}, "d":"ddd"}'::jsonb
);
jsonb_diff_val
-------------------------------------------------------------------------------
{"b": {"b1": "b1", "b2": null, "b3": {"b3c": "cccc"}}, "c": null, "d": "ddd"}
(1 row)
SELECT * FROM jsonb_object_diff(
'{"a": 1, "b": 5, "extra1": "woo", "old_null": null, "just_null": null}'::jsonb,
'{"a": 1, "b": 4, "extra2": "ahoj", "new_null": null, "just_null": null}'::jsonb);
-[ RECORD 1 ]--------------------------------------
old | {"b": 5, "extra1": "woo", "old_null": null}
new | {"b": 4, "extra2": "ahoj", "new_null": null}
same | {"a": 1, "just_null": null}
这是一个没有创建新函数的解决方案
SELECT
json_object_agg(COALESCE(old.key, new.key), old.value)
FROM json_each_text('{"a":"aaa", "b":"bbb", "c":"ccc"}') old
FULL OUTER JOIN json_each_text('{"a":"aaa", "b":"jjj", "d":"ddd"}') new ON new.key = old.key
WHERE
new.value IS DISTINCT FROM old.value
结果是
{"b" : "bbb", "c" : "ccc", "d" : null}
此方法仅比较json的第一级。它不会遍历整个对象树。感谢您的回答:创建函数似乎是件好事。但是,<代码>'{b:“bbb”,“c:“ccc”,“d”:null}'不是打字错误,因为
“d”
不在第1行,因此函数应该返回“d”:null
在我的问题中,我将“json数组”更改为“json对象”;我不知道这些定义显示我们可以在postgres 9.4中使用它。这非常优雅,Dmitry。我用它作为一个简单的json审计/日志触发器——希望没问题。您可以使用IF object_result='{}::jsonb然后
作为注释,因为jsonb_build_object
以及使用|
连接jsonb对象来测试空json对象,这是第9.5+页。我认为您可以使用json_build_object(…)::jsonb
来解决第一个问题,但我认为在9.5之前没有办法连接两个jsonb字段(没有足够的注释点),因为它工作得很好,但是jsonb_typeof(val1)=“null”检查只适用于“null”字符串/jsonb值。如果将实际null传递给val1,它将返回null。更改如果val1为NULL或jsonb_typeof(val1)=“NULL”
让我返回整个val2,对于val1为NULL的情况(此场景在执行滞后函数时出现,第一行)哇,这太棒了!