I want to create a table in ets if it does not exists. How can I check if this named exists or not?
You can use :ets.whereis/1
. It will return :undefined
if the named table does not exist:
iex(1)> :ets.new :foo, [:named_table]
:foo
iex(2)> :ets.whereis :foo
#Reference<0.2091350666.119668737.256142>
iex(3)> :ets.whereis :bar
:undefined
If you're on an older version of Erlang, you can create a lookup function:
def lookup(server, name) do
case :ets.lookup(server, name) do
[{^name, pid}] -> {:ok, pid}
[] -> :error
end
end
Information taken from: https://elixir-lang.org/getting-started/mix-otp/ets.html
Your best best is just to see if the table is in the list of all tables. A check as simple as this should be good:
lists:member(table_name,ets:all())
This returns a simple boolean() that you can use in a case to base actions on.
This should do the trick:
def create_table? do if Enum.member?(:ets.all(), :my_table) == false do:ets.new(:my_table, [:public, :named_table]) end end
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