Tuple to List - Python / PostgreSQL return type of SETOF Record

问题

so from this code:

from dosql import *
import cgi
import simplejson as json

def index(req, userID):
    userID = cgi.escape(userID)

    get = doSql()
    rec = get.execqry("select get_progressrecord('" + userID + "');", False)

    return json.dumps(rec)

Notice that the variable rec, receives a query from the database, from this defined function I created in PostgreSQL:

create or replace function
    get_progressrecord(in int, out decimal(5,2), out decimal(5,2), out decimal(4,2), out text, out int, out decimal(4,2))
    returns setof record as

$$
    select height, weight, bmi, healthStatus, age, changePercentage from progressrecord
    where userID = $1;
$$
language 'sql';

Now, suppose that the userID = 7, and the value of my table at userID (7) is:

But when I try to get that record, I receive this:

[["(300.00,30.00,3.33,underweight,21,0.00)"]]

To which I then found out (from thorough analysis), that this is a LIST OF TUPLES. Meaning, [(300.00,30.00,3.33,underweight,21,0.00)] is tuple[0] at the LIST, and (300.00,30.00,3.33,underweight,21,0.00) is element[0] at the TUPLE.

The problem is, that very (300.00,30.00,3.33,underweight,21,0.00) is recognized as ONE string or whatsoever, and it is deep down into the LIST of TUPLE. Is there other ways I could extract each element (cutting the string?) and place it into a proper list?

Like this: [300.00,30.00,3.33,underweight,21,0.00]

Much thanks. :)

回答1:

SELECT get_progressrecord(ID) will return a single column of type record.

SELECT * FROM get_progressrecord(ID) will return multiple columns (matching your out params).

As an aside, the fact that your output fields have no names might make your function a little difficult to work with. There's also an alternative syntax for RETURNS SETOF RECORD which I find easier:

CREATE OR REPLACE FUNCTION get_progressrecord(int)
  RETURNS TABLE(
    height decimal(5,2),
    weight decimal(5,2),
    bmi decimal(4,2),
    healthStatus text,
    age int,
    changePercentage decimal(4,2)
  ) AS
  ...

回答2:

You can use map function for this aim :

Demo :

>>> tuple_list=[(300.00,30.00,3.33,'underweight',21,0.00),(300.00,30.00,3.33,'underweight',21,0.00)]
>>> map(list,tuple_list)
[[300.0, 30.0, 3.33, 'underweight', 21, 0.0], [300.0, 30.0, 3.33, 'underweight', 21, 0.0]]

来源：https://stackoverflow.com/questions/26157093/tuple-to-list-python-postgresql-return-type-of-setof-record

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python

list

postgresql

tuples