Postgres 从 jsonb 数组中提取值
Postgres extract value from jsonb array
我有一个 jsonb 字段,其中包含如下所示的数组:
[
{
"type":"discount",
"title":"Discount 10%"
},
{
"file":"zx5rP8EoacyfhqGndcSOnP8VYtkr9Ya8Nvf7oYL98YDsM1CLMYIurYvfVUU4AGkzBsovwssT0bq.pdf",
"type":"menu",
"title":"Some menu title etc"
}
]
如果数组中有 type=menu,我想获取 file 属性。
我设法做的是知道是否有一个,但我如何最终提取文件值?
case when offers @> '[{"type":"menu"}]' then true else false end
我不想在下面做这样的事情,因为数组可能不包含折扣类型。
offers->1->'file'
使用 jsob_array_elements()
和 ->>
运算符(参见 JSON Functions and Operators。)
with a_table(json_col) as (
values (
'[
{
"type":"discount",
"title":"Discount 10%"
},
{
"file":"zx5rP8EoacyfhqGndcSOnP8VYtkr9Ya8Nvf7oYL98YDsM1CLMYIurYvfVUU4AGkzBsovwssT0bq.pdf",
"type":"menu",
"title":"Some menu title etc"
}
]'::jsonb)
)
select value->>'file' as filename
from a_table,
lateral jsonb_array_elements(json_col)
where value->>'type' = 'menu'
filename
---------------------------------------------------------------------------------
zx5rP8EoacyfhqGndcSOnP8VYtkr9Ya8Nvf7oYL98YDsM1CLMYIurYvfVUU4AGkzBsovwssT0bq.pdf
(1 row)
例如:
t=# with a as (with v as (select '[
{
"type":"discount",
"title":"Discount 10%"
},
{
"file":"zx5rP8EoacyfhqGndcSOnP8VYtkr9Ya8Nvf7oYL98YDsM1CLMYIurYvfVUU4AGkzBsovwssT0bq.pdf",
"type":"menu",
"title":"Some menu title etc"
}
]'::jsonb j)
select jsonb_array_elements(j) r from v) select r->>'file' from a where r->>'type' = 'menu';
?column?
---------------------------------------------------------------------------------
zx5rP8EoacyfhqGndcSOnP8VYtkr9Ya8Nvf7oYL98YDsM1CLMYIurYvfVUU4AGkzBsovwssT0bq.pdf
(1 row)
我有一个 jsonb 字段,其中包含如下所示的数组:
[
{
"type":"discount",
"title":"Discount 10%"
},
{
"file":"zx5rP8EoacyfhqGndcSOnP8VYtkr9Ya8Nvf7oYL98YDsM1CLMYIurYvfVUU4AGkzBsovwssT0bq.pdf",
"type":"menu",
"title":"Some menu title etc"
}
]
如果数组中有 type=menu,我想获取 file 属性。
我设法做的是知道是否有一个,但我如何最终提取文件值?
case when offers @> '[{"type":"menu"}]' then true else false end
我不想在下面做这样的事情,因为数组可能不包含折扣类型。
offers->1->'file'
使用 jsob_array_elements()
和 ->>
运算符(参见 JSON Functions and Operators。)
with a_table(json_col) as (
values (
'[
{
"type":"discount",
"title":"Discount 10%"
},
{
"file":"zx5rP8EoacyfhqGndcSOnP8VYtkr9Ya8Nvf7oYL98YDsM1CLMYIurYvfVUU4AGkzBsovwssT0bq.pdf",
"type":"menu",
"title":"Some menu title etc"
}
]'::jsonb)
)
select value->>'file' as filename
from a_table,
lateral jsonb_array_elements(json_col)
where value->>'type' = 'menu'
filename
---------------------------------------------------------------------------------
zx5rP8EoacyfhqGndcSOnP8VYtkr9Ya8Nvf7oYL98YDsM1CLMYIurYvfVUU4AGkzBsovwssT0bq.pdf
(1 row)
例如:
t=# with a as (with v as (select '[
{
"type":"discount",
"title":"Discount 10%"
},
{
"file":"zx5rP8EoacyfhqGndcSOnP8VYtkr9Ya8Nvf7oYL98YDsM1CLMYIurYvfVUU4AGkzBsovwssT0bq.pdf",
"type":"menu",
"title":"Some menu title etc"
}
]'::jsonb j)
select jsonb_array_elements(j) r from v) select r->>'file' from a where r->>'type' = 'menu';
?column?
---------------------------------------------------------------------------------
zx5rP8EoacyfhqGndcSOnP8VYtkr9Ya8Nvf7oYL98YDsM1CLMYIurYvfVUU4AGkzBsovwssT0bq.pdf
(1 row)