Как преобразовать XML в JSONB в Postgres

Question

У меня есть таблица, Table1, содержащий XML data type колонку, ColumnA и еще один столбец JSONB ColumnB

Как преобразовать данные из ColumnA в ColumnB, предположительно с помощью SQL UPDATE заявление. Есть ли встроенная функция в Postgres, которая делает это?

Answer 1

Нет никаких функций из коробки, как я знаю.

Try:

create or replace function xml_to_json(p_xml xml) returns jsonb as $$ 
declare 
    result json; 
    root text; 
    childs jsonb; 
    attr jsonb; 
    txt text; 
begin 
    -- Get root element name 
    select (xpath('name(/*)', p_xml))[1]::text into root; 

    -- Process child nodes 
    select json_agg(xml_to_json(z)) 
    from unnest(xpath('/'||root||'/*', p_xml)) with ordinality as c(z,i) 
    into childs; 

    -- Read attributes 
    select jsonb_agg(jsonb_build_object((xpath('name(/'||root||'/@*['||i||'])', p_xml))[1]::text, v)) 
    from unnest(xpath('/'||root||'/@*', p_xml)::text[]) with ordinality as a(v,i) 
    into attr; 

    -- Read text 
    select (xpath('/'||root||'/text()', p_xml))[1]::text into txt; 

    -- Build object 
    result := jsonb_build_object(root, jsonb_build_object('attr', attr, 'text', txt, 'childs', childs)); 
    return result; 
end $$ language plpgsql immutable; 

Тест:

with t(x) as (values 
('<root bar="foo" name="test" foo="bar"> 
    <aaa bbb="111"> 
    foo 
    bar 
    </aaa> 
    <bbb> 
    <ccc>222</ccc> 
    </bbb> 
</root>'::xml), 
('<?xml version="1.0" encoding="UTF-8"?> 
<bookstore> 
    <book> 
    <title lang="en">Harry Potter</title> 
    <price>29.99</price> 
    </book> 
    <book> 
    <title lang="en">Learning XML</title> 
    <price>39.95</price> 
    </book> 
</bookstore>')) 
select jsonb_pretty(xml_to_json(x)) from t; 

И выход:

     jsonb_pretty      
--------------------------------------------------------- 
{              + 
    "root": {           + 
     "attr": [          + 
      {           + 
       "bar": "foo"       + 
      },           + 
      {           + 
       "name": "test"       + 
      },           + 
      {           + 
       "foo": "bar"       + 
      }           + 
     ],            + 
     "text": "\n ",        + 
     "childs": [         + 
      {           + 
       "aaa": {        + 
        "attr": [       + 
         {        + 
          "bbb": "111"    + 
         }        + 
        ],         + 
        "text": "\n foo\n bar\n ", + 
        "childs": null      + 
       }          + 
      },           + 
      {           + 
       "bbb": {        + 
        "attr": null,      + 
        "text": "\n ",     + 
        "childs": [      + 
         {        + 
          "ccc": {     + 
           "attr": null,   + 
           "text": "222",   + 
           "childs": null   + 
          }       + 
         }        + 
        ]         + 
       }          + 
      }           + 
     ]            + 
    }             + 
} 
{              + 
    "bookstore": {          + 
     "attr": null,         + 
     "text": "\n ",        + 
     "childs": [         + 
      {           + 
       "book": {        + 
        "attr": null,      + 
        "text": "\n ",     + 
        "childs": [      + 
         {        + 
          "title": {     + 
           "attr": [    + 
            {     + 
             "lang": "en" + 
            }     + 
           ],      + 
           "text": "Harry Potter",+ 
           "childs": null   + 
          }       + 
         },        + 
         {        + 
          "price": {     + 
           "attr": null,   + 
           "text": "29.99",  + 
           "childs": null   + 
          }       + 
         }        + 
        ]         + 
       }          + 
      },           + 
      {           + 
       "book": {        + 
        "attr": null,      + 
        "text": "\n ",     + 
        "childs": [      + 
         {        + 
          "title": {     + 
           "attr": [    + 
            {     + 
             "lang": "en" + 
            }     + 
           ],      + 
           "text": "Learning XML",+ 
           "childs": null   + 
          }       + 
         },        + 
         {        + 
          "price": {     + 
           "attr": null,   + 
           "text": "39.95",  + 
           "childs": null   + 
          }       + 
         }        + 
        ]         + 
       }          + 
      }           + 
     ]            + 
    }             + 
} 
(2 rows)