如何将jsonarray从hive转换为多列答案

【问题标题】：how to convert jsonarray to multi column from hive如何将jsonarray从hive转换为多列
【发布时间】：2020-07-15 05:03:13
【问题描述】：

示例：蜂巢表中有一个 json 数组列（类型：字符串），例如：

"[{"filed":"name", "value":"alice"}, {"filed":"age", "value":"14"}......]"

如何转换成：

name      age
alice     14

通过 hive sql？我试过横向视图爆炸，但它不起作用。非常感谢！

【问题讨论】：

是STRING列类型吗？
是，字符串类型

标签： sql json hive hiveql

【解决方案1】：

这是如何在 Hive 中解析它的工作示例。自己定制，在真实数据上调试，见代码中的cmets：

with your_table as (
select stack(1,
1,
'[{"field":"name", "value":"alice"}, {"field":"age", "value":"14"}, {"field":"something_else", "value":"somevalue"}]'
) as (id,str) --one row table with id and string with json. Use your table instead of this example
)


select id, 
       max(case when field_map['field'] = 'name' then field_map['value'] end) as name,
       max(case when field_map['field'] = 'age'  then field_map['value'] end) as age        --do the same for all fields 
from
(
select t.id,
       t.str as original_string,
       str_to_map(regexp_replace(regexp_replace(trim(a.field),', +',','),'\\{|\\}|"','')) field_map --remove extra characters and convert to map
  from your_table t
       lateral view outer explode(split(regexp_replace(regexp_replace(str,'\\[|\\]',''),'\\},','}|'),'\\|')) a as field --remove [], replace "}," with '}|" and explode 
) s 
group by id --aggregate in single row
;

结果：

OK
id      name    age
1       alice   14

另一种使用 get_json_object 的方法：

with your_table as (
select stack(1,
1,
'[{"field":"name", "value":"alice"}, {"field":"age", "value":"14"}, {"field":"something_else", "value":"somevalue"}]'
) as (id,str) --one row table with id and string with json. Use your table instead of this example
)


select id, 
       max(case when field = 'name' then value end) as name,
       max(case when field = 'age'  then value end) as age        --do the same for all fields 
from
(
select t.id,
       get_json_object(trim(a.field),'$.field') field,
       get_json_object(trim(a.field),'$.value') value
  from your_table t
       lateral view outer explode(split(regexp_replace(regexp_replace(str,'\\[|\\]',''),'\\},','}|'),'\\|')) a as field --remove [], replace "}," with '}|" and explode 
) s 
group by id --aggregate in single row
;

结果：

OK
id      name    age
1       alice   14

【讨论】：