mnesia primary key
- by maryjanne
Hi
I have two tables one notes and one tag and I want to make the id from notes primary key to use it in the tag table, but I don't know where I do wrong. My notes id is generate from another table counter, with the function dirty_update_counter.
My function for the id_notes from tag looks like this:
Fun = fun() ->
mnesia:write(#tag{ id_note =0})
end,
mnesia:transaction(Fun).
generate_Oid(TableName) when is_atom(TableName) ->
F = fun() ->
[Oid] = mnesia:read(tag, TableName, write),
NewId = Oid#tag.id_note+1,
New = Oid#tag{id_note = NewId},
mnesia:write(New),
NewId
end,
mnesia:transaction(F).
insert_n(N) when is_record(N, note) ->
F = fun() ->
{atomic, Id} = generate_Oid(note),
New = N#note{id = Id},
mnesia:write(New),
New
end,
mnesia:transaction(F).
find_n(Id) when is_integer(Id) ->
{atomic, [N]} = mnesia:transaction(fun() ->
mnesia:read({note, Id})
end),
N.
But this function don't increment my field id_note from the table tag, despite the fact that in my note table, my id field is incremented from counter table.
Thanks in advance for any help.
