Postgres JSONB:数组数组的where子句

Question

在postgres(第9.5节,如果有关系):

create table json_test(
 id varchar NOT NULL,
 data jsonb NOT NULL,
 PRIMARY KEY(id)
);

数据是json并包含数组的数组

{
    "attribute": "0",
    "array1": [{
        "id": "a12",
        "attribute": "1",
        "array2": [{
            "id": "a21",
            "attribute": "21"
        }]
    },
    {
        "id": "a12",
        "attribute": "2",
        "array2": [{
            "id": "22",
            "attribute": "22"
        }]
    }]
}

需要:

select id from json_test where 
    json_test->>'attribute'='0' and
    array1.[id='a12'].array2.attribute='22'

查询应该意味着:给我所有的ID

1. 一些顶级属性具有特定值
2. 数组中的特定对象具有必需属性
3. 某些对象(来自array2),特别是array1具有必需的属性

诀窍是如何实现最后一个条件.

---

另一个例子:

{
    "attribute": "0",
    "array1": [{
        "id": "a12",
        "attribute": "1",
        "array2": [{
            "id": "a21_1",
            "attribute_1": "21_1"
        },{
            "id": "a21_2",
            "attribute_2": "21_2"
        }]
    }]
}

select * from json_test where 
    array1.[id='a12'].array2.attribute_1='21_1' and  
    array1.[id='a12'].array2.attribute_2='21_2'

Answer 1

检索嵌套json数组的最常用方法是jsonb_array_elements()在横向连接中使用多个.例:

with json_test(id, data) as (
    values
        (1, 
        '{
            "attribute": "0",
            "array1": [{
                "id": "a12",
                "attribute": "1",
                "array2": [{
                    "id": "a21",
                    "attribute": "21"
                }]
            },
            {
                "id": "a12",
                "attribute": "2",
                "array2": [{
                    "id": "22",
                    "attribute": "22"
                }]
            }]
        }'::jsonb)
    )

select id, elem2
from 
    json_test, 
    jsonb_array_elements(data->'array1') array1(elem1),
    jsonb_array_elements(elem1->'array2') array2(elem2)
where elem2->>'id' = '22';

 id |              elem2              
----+---------------------------------
  1 | {"id": "22", "attribute": "22"}
(1 row)

该方法是通用的,因为您可以在任何级别轻松访问任何json对象的任何值,例如:

...
where 
    data->>'attribute' = '0'
    and elem1->>'id' = 'a12'
    and elem2->>'id' = 'a21_1';