Hi,
It’s a long story.
The short answer is: you can’t with that client, it has strong opinions so the
best thing to do is this: have your app interpret the absence of a flag as
false (the bottom/default value for a flag.)
The long story: the semantic for the flag is “observed remove” or “add-wins”
(in fact the semantic is “add-wins”, “observe remove” is just how it does it)
which means you have to observe an enabled flag (which will have a context) in
order to disable it. The context tells riak at exactly what logical time you
observed the enabled flag. This is to prevent a request to “disable flag” at
the same logical time as an “enable flag” winning over the “enable” in a
race/by chance. Ideally the absence of a flag would be indicated by the client
as the flag’s default/bottom value (disabled/false) however, for some reason we
went with a kind of 3-state deal of does-not-exist/enabled/disabled. My opinion
is that this was a bad idea. But it is the state of the world, and so we have
to live with it for now. In future, I think it should be possible to use
“new/0” to create a flag in the bottom state. It’s something we know how to do,
we just haven’t done it yet. Sorry.
Cheers
Russell
On 6 Aug 2015, at 17:43, 王昊 <jusf...@163.com> wrote:
> When I try this in Erlang:(saving a new Map object to a bucket through )
>
> Map = riakc_map:new(),
> Map1 = riakc_map:update({<<"published_b">>, flag},
> fun(F) -> riakc_flag:disable(F) end, Map);
>
> I got context_required. How could I create a false flag? I tried enable/1, it
> seems ok. Should I use new/0?
>
> --
>
> Hao Wang
>
>
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