store 0 foreign key as NULL if the field is NULL
store 0 foreign key as NULL if the field is NULL

paradoxon82/qdjango,paradoxon82/qdjango,ericLemanissier/qdjango,paradoxon82/qdjango,ericLemanissier/qdjango,jlaine/qdjango,paradoxon82/qdjango,ericLemanissier/qdjango,jlaine/qdjango,ericLemanissier/qdjango,ericLemanissier/qdjango,jlaine/qdjango,jlaine/qdjango,jlaine/qdjango,paradoxon82/qdjango