Thanks a lot. Fixing `CREATE FUNCTION` statement fixed the crash issue.
On Tue, Mar 19, 2019 at 3:18 PM Michel Pelletier <pelletier.michel@xxxxxxxxx> wrote:
For server crashes you can't beat gdb in my opinion. It's a challenge but worth it in the long run to have gdb skills if you're coding in C (or Python, since pdb shares many of gdb's keybindings).But just looking at the function I don't see what's immediately wrong, what's your CREATE FUNCTION statement look like?On Tue, Mar 19, 2019 at 1:08 PM T L <tinlyx@xxxxxxxxx> wrote:Thanks a lot for the hint. I've used the iteration style and cleaned up the code as far as I can.It now correctly prints the keys and values, but the server crashes near function return.Any suggestions?-- function code --PG_FUNCTION_INFO_V1(print_kv_pair);
Datum
print_kv_pair(PG_FUNCTION_ARGS)
{
//1. extracting JsonbValue
Jsonb *jb = PG_GETARG_JSONB_P(0);
JsonbIterator *it;
JsonbValue v;
JsonbIteratorToken r;
JsonbParseState *state = NULL;
if (jb == NULL)
PG_RETURN_BOOL(false);
if (!JB_ROOT_IS_OBJECT(jb))
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("Can only take objects")));
it = JsonbIteratorInit(&jb->root);
r = JsonbIteratorNext(&it, &v, false);
if (r != WJB_BEGIN_OBJECT)
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("Iterator was not an object")));
//2. iterating through key-value pairs
char *buf;
while ((r = JsonbIteratorNext(&it, &v, true)) != WJB_DONE)
{
switch (r) {
case WJB_KEY:
buf = pnstrdup(v.val.string.val, v.val.string.len);
elog(NOTICE, "print_kv_pair(): k = %s", buf); //debug
break;
case WJB_VALUE:
if (v.type != jbvNumeric) {
ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("value must be numeric")));
}
elog(NOTICE, "print_kv_pair(): v = %s", DatumGetCString(DirectFunctionCall1(numeric_out,
NumericGetDatum(v.val.numeric))) ); //debug
break;
case WJB_END_OBJECT:
break;
default:
elog(ERROR, "invalid JsonbIteratorNext rc: %d", (int ) r);
}
}
elog(NOTICE, "print_kv_pair(): ok4");
PG_RETURN_BOOL(true);
}-- output --=> select print_kv_pair('{"a":1, "b": 2}');
NOTICE: print_kv_pair(): k = a
NOTICE: print_kv_pair(): v = 1
NOTICE: print_kv_pair(): k = b
NOTICE: print_kv_pair(): v = 2
NOTICE: print_kv_pair(): ok4
server closed the connection unexpectedly
This probably means the server terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset: Failed.
!>On Tue, Mar 19, 2019 at 2:22 PM Michel Pelletier <pelletier.michel@xxxxxxxxx> wrote:jsonb_each is a wrapper around each_worker_jsonb. It produces a row for every key/value pair in an object.the iteration is:while ((r = JsonbIteratorNext(&it, &v, skipNested)) != WJB_DONE)On Tue, Mar 19, 2019 at 11:20 AM T L <tinlyx@xxxxxxxxx> wrote:I need this in my C code on the server side. Any link to the `jsonb_each` for this? Examples I found in a quick search are on the client side in SQL.I am just confused about the various jsonb types and how to effectively extract values and convert between them:There are Jsonb, JsonbValue (plus the associated JsonbPair ) to begin with. The ` JsonbToCStringWorker ` example that Andrew pointed out uses still another "JsonbContainer" type.But the type I get from "PG_GETARG_JSONB_P" is Jsonb. And it doesn't fit into " JsonbContainer" or the pointer math about "JsonPair" that I found online.What I am struggling with adapting some of the iterator code I saw is how to delete irrelevant code without breaking it. My use case is very restricted and handles hstore-like jsonb's.I don't need or want the code to have the ability to descend into nested objects or handle arrays etc., as they are invalid input in my case.I thought the pointer math example I found is easier to adapt, but I couldn't get a valid "JsonbPair" from the input parameter to feed into the pointer math.On Tue, Mar 19, 2019 at 9:50 AM Michel Pelletier <pelletier.michel@xxxxxxxxx> wrote:Yeah I'm not sure why you're looping using pointer math, the iterators are there to provide that service. Another function to check out 'jsonb_each', other than the set returning function parts, it does what it looks like your are trying to do.-MichelOn Mon, Mar 18, 2019 at 4:12 PM Andrew Gierth <andrew@xxxxxxxxxxxxxxxxxxxx> wrote:>>>>> "T" == T L <tinlyx@xxxxxxxxx> writes:
T> Below is my test. It prints a strange character instead of "a"; and
T> says that the value isn't numeric.
Yeah, there's plenty else wrong with your code.
Did you look at how JsonbToCStringWorker does it? that looks like the
best example I can find on a quick scan.
--
Andrew (irc:RhodiumToad)
