On Thu, Nov 14, 2024 at 9:37 PM Artyom Beilis via Boost
The Boost formal review of the Boost SQLITE library starts *TODAY*, taking place
Documentation: https://klemens.dev/sqlite/
Several questions to the author regarding documentation and API (not a review yet)
1. Transactions.
I noticed that you call explicitly begin/connit
conn.query("begin transaction;"); ... conn.query("commit;");
Both soci [1] and cppdb [2] and most database wrappers I have seen provide scopes that allow to commit or rollback in case of failure/exception. It is something very common and allowshandling translations in an exception safe way.
Do you provide such a feature?
yes, sqlite::transaction: https://klemens.dev/sqlite/structboost_1_1sqlite_1_1transaction.html It does not commit in the destructor, but always calls rollback if there was no explicit commit.
2 Example
boost::sqlite::row r; boost::sqlite::query q = conn.query(...) do { auto r = q.current();'' std::cout << r.at(0u).get_text() << " authored " << r.at(1u).get_text() << std::endl; } while (q.read_next());
What happens when the result is empty? I'd rather expect to see for(;;) or while loop. How do I check if the result is valid? How do I manually iterate over the result without an automatic "for" loop.
boost::sqlite::query q = conn.query(...); if (q.read_next()) // read another row If the result is empty q.done() is true. Invalid results would lead to exception unless you use the `error_code&` overloads, e.g. boost::system::error_code ec; boost::sqlite::error_info ei; boost::sqlite::query q = conn.query(...,, ec, ei); if (!ec) if (q.read_next(ec, ei)) // read another row
3. What happens if you do not read the entire result? How do you abort the query? As far as I remember if you'll execute another statement when you hadn't finished you'll get SQLITE_BUSY error
Aborting the query is done by letting the `query` object go out of scope.
4. Both soci and cppdb have some syntactic sugar to query a single row - for example when querying something by primary key. Can you do it without a loop?
sqlite::row r = conn.query(...).row() ; or author a = conn.query<author>(...).row();
5. How do you handle locks/collisions when two processes try to update the same DB. It is a tricky bit in sqlite - sometimes you need to wait, sometimes to abort.
That would just be an error, there's no explicit handling in the library.
I noticed the word "error" appears only once in a tutorial... Please add documentation on error handling
Will do. Most functions have an overload taking an error_code & error_info by reference for the error and one that will throw an exception.
6. Are objects copyable or only moveable? Please state explicitly
Most are move-only. It's documented in the reference.
Disclosure: I'm the author of cppdb and contributed to/used in past soci.
Artyom Beilis
1) https://soci.sourceforge.net/doc/master/transactions/ 2) http://cppcms.com/sql/cppdb/transaction.html
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