Hello,
I have a vtable implementation that wraps a storage layer of my own
using Sqlite 3.5.6 (which is excellent--kudos!).
If the user does an SQL INSERT statement but provides the wrong type
(according to my storage manager) for one of the values, I'd like to
report a descriptive error message. For example, if the user has a
table "foo", with one column, "bar", of type integer, and says:
sqlite> INSERT INTO foo VALUES ("Hello, world!");
I'd like sqlite to say:
Error: datatype mismatch: column "bar" of table "foo" is of type INTEGER.
Currently, my code looks something like this:
static int
vt_update(sqlite3_vtab *pVTab, int argc, sqlite3_value **argv,
sqlite3_int64 *pRowid)
{
...
for (int i = 2; i < argc; ++i) {
if (sqlite3_value_type(argv[i]) != my_table_types[i]) {
if (vtab->zErrMsg)
sqlite3_free(vtab->zErrMsg);
vtab->zErrMsg = sqlite3_mprintf("column %s of table %s is
of type %s", ...);
return SQLITE_MISMATCH;
}
...
}
}
When I try the example above, I get:
sqlite> INSERT INTO foo VALUES ("Hello, world!");
SQL error: datatype mismatch
The documentation at http://www.sqlite.org/cvstrac/wiki?p=VirtualTables says:
"The virtual table implementation can pass error message text to the
core by putting an error message string obtained from
sqlite3_mprintf() in zErrMsg. Prior to assigning a new value to
zErrMsg, the virtual table implementation should free any prior
content of zErrMsg using sqlite3_free(). Failure to do this might
result in a memory leak. The SQLite core will free and zero the
content of zErrMsg when it delivers the error message text to the
client application or when it destroys the virtual table."
That leads me to believe I should see my message ('column "bar" of
table "foo" is of type INTEGER') echoed to the user. Is that not the
case? Am I missing something obvious?
Thanks in advance for your help,
Sean
--
"We're borrowing money from China to buy oil from the Persian Gulf to
burn it in ways that destroy the planet. Every bit of that's got to
change." -- Al Gore
_______________________________________________
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
