Hi David,

thanks for the confirmation. Is there a way I can detect if the
component is mounted? I first tried adding a :mounted? flag to
component state and set/change it in will-mount and
will-unmount. But I get the same error when I call om/set-state!
in will-unmount.

Roman

On Monday, May 5, 2014 11:43:33 PM UTC+2, David Nolen wrote:
> Setting up go blocks in mount/unmount is fine in my opinion, but yes, you 
> must handle the concurrency issues that arise from doing this.
> 
> 
> David
> 
> 
> 
> 
> On Mon, May 5, 2014 at 5:32 PM, Roman Scherer <[email protected]> 
> wrote:
> 
> Hi,
> 
> 
> 
> I think I'm running into a race condition while using om and
> 
> core.async. I have code like this:
> 
> 
> 
>     om/IWillMount
> 
>     (will-mount [this]
> 
>       (go (let [image (<! (load-image (om/get-state owner :url)))]
> 
>             (om/set-state! owner :width (:width image))
> 
>             (om/set-state! owner :height (:height image)))))
> 
> 
> 
> The load-image fn returns a channel. Then I do a blocking read on
> 
> that channel and at some point later, it returns a map which I
> 
> save to the component's local state.
> 
> 
> 
> Mounting, unmounting and remounting works fine with one
> 
> component. However, when I have more than one instances of this
> 
> component and I remount them I get most of the time the following
> 
> error.
> 
> 
> 
>     Uncaught Error: Invariant Violation: forceUpdate(...): Can
> 
>     only force an update on mounted or mounting components.
> 
> 
> 
> This looks like the calls to om/set-state! within the go block
> 
> are sometimes called when the component is already unmounted.
> 
> 
> 
> Now I'm wondering if I'm doing something wrong and have some
> 
> questions.
> 
> 
> 
> * Is it bad style to use go blocks in the will-mount/did-mount fn
> 
> and set state in them?
> 
> 
> 
> * Do other people have similar issues, and how to work around?
> 
> 
> 
> * Any other idea what's going on?
> 
> 
> 
> Thanks, Roman.
> 
> 
> 
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