Josh, I'm running into a similar problem.  I want to trigger a global error 
handler whenever any of my components error, (a 401 from session expiration 
for example), but I want to be able to spread out my api throughout my 
components.

On Tuesday, July 5, 2016 at 7:53:29 AM UTC-7, Josh Adams wrote:
>
> I would handle this entirely differently, personally.  I'm inclined to 
> have an API TEA component as a child at the Root, and send up messages 
> requesting API calls to it.  I would never spread my API requests out 
> through components.
>
> That's just me though - I know other people handle this way differently. 
>  Would love to hear any suggestions from more experienced folks re: this :)
>
> -Josh
> http://www.dailydrip.com/topics/elm
>
> On Tuesday, July 5, 2016 at 7:46:16 AM UTC-5, Erik Lott wrote:
>>
>> My app has several layers of nested components. Various components 
>> throughout the tree will need to interact with our API via http requests. 
>> If any API request returns a 401 - Not Authorized error, or a Timeout 
>> Error, the error needs to bubble up to the root component where is can be 
>> handled appropriately.
>>
>> What is the most idiomatic way of dealing with this? 
>>
>> *1. Parent should pattern match against important child messages*: 
>> Reference 
>> <https://groups.google.com/d/msg/elm-discuss/QPqrJd4C78Y/_TLLg81SAQAJ>
>> This could work, but would be unreasonable in this case. The root 
>> component would need to match against every failing api http request made 
>> by every child, grandchild, great-grandchild, etc, component in the tree. 
>> If a single pattern is missed, the app would be in an error state, so this 
>> is prone to mistakes.
>>
>> *2. Nested Components return additional info from the "update" function*: 
>> Reference 
>> <http://stackoverflow.com/questions/37328203/elm-0-17-how-to-subscribe-to-sibling-nested-component-changes>
>> Each component returns an additional value from its update function like 
>> this:
>> update : Msg -> Model -> (Model, Cmd Msg, SomeInfo)
>>
>> The parent component could inspect the returned "SomeInfo" value from its 
>> direct children, and act on that information if necessary.  In my case, any 
>> nested component that makes http requests to our API would be responsible 
>> for returning a APINotAuthorized and APITimeout value to its parent, and 
>> its parent would do the same, until the error has bubbled up to the root 
>> component.
>>
>>
>> Option 2 is simple and robust, and can be used to pass messages of any 
>> type, for any situation... but I'm wondering if I'm missing an obvious 3rd 
>> solution?
>>
>

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