Hi,
Another question of idiomatic usage (will somebody *please* right a
"JoyOfClojure" type book about om ;)).
I have a hierarchy in my app-state (e.g. a hierarchy of locations). I also have
app-state which stores the ids of the nodes that are selected {:reference
{:locations {:id 1 :text "All locations" :children [...]}} :ui {:page-1
{:locations {:selected-ids []}}}}.
However, for the purposes of this question let's assume I don't want to store
the ids of the expanded nodes.
My question is where to store this state:
[tree local state in an expanded-ids []]
If I do this (i.e. the tree's IInitState returns {:expanded-ids []}). Each
component node in the tree is passed {:expanded? (id-in? (:id node)
expanded-ids). Every time I expand or collapse the tree the tree component's
top-level state (i.e. the expanded-ids vector) is changed which causes the
whole tree to re-render.
[tree local state in a projected-tree]
In this scenario the component state is a hierarchy that merges the underlying
(e.g. locations) tree with an "expanded?": {:id 1 :text "All locations"
:children [...] :expanded? bool). As before, each tree node is now mapped to an
individual node however, expanding or collapsing the tree only changes the data
that a specific node is referencing so only that node needs to be re-rendered?
[no local state]
In this scenario there is no local state and it all comes from the app-state.
This is actually a red herring as the question is the same - what data
structure do you store?
In both scenarios the same amount of dom manipulation is done due to om's
optimisations and react's fantastic diff engine, but in the first the whole
component is re-rendered, in the second only the individual node is re-rendered.
It would seem that the second approach is the way to go, the more expensive the
rendering the truer this is, except it has an additional complexity of
wrangling together a bunch of data structures (as well as expanded there might
be many more).
Firstly, are my assumptions correct (they seem to be based on my initial
investigations) and secondly, what do you all do?
(Has anyone thought of writing a book on this stuff? I can't be the only person
who has been doing this a while and been completely blown out of the water by
the whole "treat the dom like a projection/state-machine/pure function" mind
set?)
--
Note that posts from new members are moderated - please be patient with your
first post.
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