On Wednesday, April 9, 2014 at 1:52:05 PM UTC+3, David Nolen wrote: > You're not missing anything. This is a fundamental issue in Om right now and > I've been designing and working on a fix. Basically in the very near future a > component will be able to access something in the application state without > needing a parent component to pass it in from above. > > > > The idea is that a component will be able to get its data directly from the > app state with something like (om/get-shared owner [:app-state :foo]). > > > Still working out the details, but this work is happening in the > `ind-components` branch. When it's finished there'll be an accompanying > nested tab view example - one of the cases that suffers the most under the > current system. > > > > > David > > > > On Wed, Apr 9, 2014 at 6:33 AM, Daniel Kersten <dker...@gmail.com> wrote: > > > Hi, > > > I'm trying to figure out the best way of structuring complex applications in > Om and I've hit a bit of a brick wall that I'm hoping someone can help me > with. > > > > > > I like the concept of cursors - narrow down the application state to what the > individual components actually need and allow them to read and modify only > that. > > > The problem I'm having is that I don't know how to structure my state so that > the correct components have access to everything they need. Its easy if each > component only requires a strict subset of its parent, which is often the > case, but not always. I've hit a scenario where a component needs access to > two very different branches of the app state and I'm not sure how to pass it > to the component that needs it. > > > > > > As a (contrived) example, imagine you had an app for displaying orders in an > online store and the application state is something like this: > > > (def app-state (atom {:items [{:type "book" :price 123} {:type "cd" :price > 200}] > > > > :orders [{:date xxx :type "book" :count 3} {:date yyy > :type "cd" :count 1}] > :filter "book"})) > > > > > > You can imagine that in a real application the :items and :orders branches > may be much deeper. > > > Lets say I now have two components, one displaying the items (so it is passed > a cursor with path [:items]) and one displaying the orders (so it is passed a > cursor with path [:orders]). What if I now only want to display items and > orders where the type matches the filter? > > > > > > I have a few options: > Restructure the app state in a way that gives each component access to what > it needs. This is not ideal as it means that I'm modelling my state after how > its being rendered rather than how its being processed and makes it very > application specific. > > > I can propagate the additional values down the component tree (eg using the > :state parameter to build), but this means that every other component before > the one that consumes it must now do additional work that it shouldn't need > to know about (couples the parent components too tightly to the child one) > > > Similarly, passing it in opts is not ideal as it has the same issue as #2, > with the added caveat that the component also won't rerender on change.I can > store the value in component local state and update it through a core.async > channel. This works well in the example above, where one or two simple values > need to be communicated, but gets unruly when the application is more complex. > > > I can pass the entire app state to each component (perhaps trough shared > state) and use transformation functions (similar to what Sean Grove did in > his recent slides) to transform the state into a local view for each > component. This means each component gets to select exactly what it needs to > access without worrying about what comes before or after it in the hierarchy, > but then you lose the benefit of cursors and automatic re-rendering when > something changes. > > > > > > I'm sure I'm missing something! > > > Any tips appreciated. > > > Dan. > > > > > -- > > Note that posts from new members are moderated - please be patient with your > first post. > > --- > > You received this message because you are subscribed to the Google Groups > "ClojureScript" group. > > To unsubscribe from this group and stop receiving emails from it, send an > email to clojurescrip...@googlegroups.com. > > To post to this group, send email to clojur...@googlegroups.com. > > Visit this group at http://groups.google.com/group/clojurescript.
David, are these changes done yet? Are they documented anywhere? -- Note that posts from new members are moderated - please be patient with your first post. --- You received this message because you are subscribed to the Google Groups "ClojureScript" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojurescript+unsubscr...@googlegroups.com. To post to this group, send email to clojurescript@googlegroups.com. Visit this group at http://groups.google.com/group/clojurescript.