November 2012
Intermediate to advanced
888 pages
54h 46m
Polish
Content preview from Ruby. Receptury
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13.16. Obsługa transakcji z wykorzystaniem biblioteki ActiveRecord
Problem
Chcemy wykonywać operacje z bazą danych w sposób transakcyjny: jeśli jedna z operacji w ciągu nie powiedzie się, baza danych ma znaleźć się w takim stanie, jakby nie wykonała się żadna z tych operacji.
Rozwiązanie
Można włączyć plik active_record/transactions. Dzięki temu dla każdego obiektu klasy ActiveRecord będzie dostępna metoda transaction. Metoda ta rozpoczyna transakcję z bazą danych, uruchamia blok kodu, a następnie zatwierdza transakcję. Jeśli blok kodu zgłosi wyjątek, transakcja z bazą danych zostanie wycofana.
Oto prosty kod inicjujący, który daje bibliotece ActiveRecord dostęp do bazy danych systemu weblog zaprezentowanego po raz pierwszy w „13.11. ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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