Question

我想在json下面的a3中添加一个新的数组元素：

{
    "a1": "e1",
    "a2": {
        "b1": "y1",
        "b2": "y2"
    },
    "a3": [{
            "arr1": "1"
        },
        {
            "arr2": "2"
        }
    ]
}

所以我希望上面的json像这样：

{
    "a1": "e1",
    "a2": {
        "b1": "y1",
        "b2": "y2"
    },
    "a3": [{
            "arr1": "1"
        },
        {
            "arr2": "2"
        },
        {
            "arr3": "3"
        }
    ]
}

我可以使用以下命令添加新元素。但是当涉及到数组时，我找不到添加新元素的方法。

SELECT jsonb_set('{ "a1": "e1", "a2": { "b1": "y1", "b2": "y2" }, "a3": [{ "arr1": "1" }, { "arr2": "2" }] }'::jsonb,
'{a2,b3}', 
'"4"');

我要使用什么命令将{“ arr3”：“ 3”}添加到a3？

edit：如果arr3已经存在，则该命令应更改其值。不应添加重复的{“ arr3”：“ 3”}。

Answer 1

对数组使用串联运算符||：

with my_data(json_data) as (
values
    ('{ "a1": "e1", "a2": { "b1": "y1", "b2": "y2" }, "a3": [{ "arr1": "1" }, { "arr2": "2" }] }'::jsonb)
)

select jsonb_set(json_data, '{a3}', json_data->'a3' || '{"arr3": "3"}')
from my_data;

                                             jsonb_set                                             
---------------------------------------------------------------------------------------------------
 {"a1": "e1", "a2": {"b1": "y1", "b2": "y2"}, "a3": [{"arr1": "1"}, {"arr2": "2"}, {"arr3": "3"}]}
(1 row)

检查键是否在嵌套数组中存在有点复杂。您应该使用jsonb_array_elements()取消嵌套数组的操作：

with my_data(json_data) as (
values
    ('{ "a1": "e1", "a2": { "b1": "y1", "b2": "y2" }, "a3": [{ "arr1": "1" }, { "arr2": "2" }] }'::jsonb)
)

select 
    case when already_exists then json_data
    else jsonb_set(json_data, '{a3}', json_data->'a3' || '{"arr3": "3"}')
    end as json_data
from (
    select json_data, bool_or(value ? 'arr3') as already_exists
    from my_data
    cross join jsonb_array_elements(json_data->'a3')
    group by 1
    ) s

向Json数组添加新元素

1 个答案: