PostgREST自定义函数平面数组代替key:value

Question

我使用这个自定义函数从datalist查询group by。结果，我收到了唯一的查询结果，但作为嵌套对象[{substance: 'value'}]。它更希望我的回答是[value, value, value]。

SQL：

create or replace function api.substances(substance_group text) returns table(substance text) 
as 'select api.emissions.substance from api.emissions where api.emissions.substance_group = $1 group by api.emissions.substance;'
language sql;

响应：

[
  {
    "substance": "Arseen"
  },
  {
    "substance": "Benzo[b]fluorantheen"
  },
  ...
]

需要响应：

[
  "Arseen",
  "Benzo fluorantheen",
  ...
]

Answer 1

您需要返回一个文本数组(text[])而不是table(text)，并对查询使用array_agg函数。像这样：

create or replace function api.substances(substance_group text) returns text[] as $$
  select array_agg(api.emissions.substance)
  from api.emissions
  where api.emissions.substance_group = $1
  group by api.emissions.substance;
$$ language sql;