Part 10 MDriven Designer Overview. Actions and navigation
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hi and welcome, I've promised to do a
video on windows and navigation or
views and navigation, now, let's start from the beginning
let's say we have nothing and we have
this single class with an attribute, this is all we have and
well we have the definition of information
but we have nothing else, so in order to view this information
we need a view model and let's do that
so that's the view this and we say what
kind of class it is and when we have
done that, we can add attribute1 that
would be our view, since the debugger
or the prototyper, when the field is next to the end like this,
it's expanded, so let's make this a little bigger
so it's not next to the end, 2 by 3, like that
ok, so now we have information and a view
but we don't have any way to get here
that's where the actions come in
they should be here, of course this is called repetition, so far
let's do a global action, which are the
actions, that show up in the main menu
and this global action, let's make it
bring up the ViewModel1, so all we have
said now is that the main menu
should have a action called new global action
and it should bring a ViewModel1
let's see what happens and when around
that, so we have the new global action 1
and it brings up a viewmodel, but this is a bit treacherous
it's a viewmodel, but we don't have any object in it
we know, it should be of class1
but there really isn't any object of class1
as of yet and why is that, well it's
because the viewmodel root object expression is empty, so we really need to
provide object, so that this expression
has something to work with and let's
make this a bit clearer by adding a
generic column with a expression, that we say
self.isnull, that would be bulean
if in end show the checkbox
that would be checked, if this is null
so, is this really null and let's make
a little bit bigger  then
so re-fresh the model and new global action, is this really null
yeah, so that one is checked, so that's a
problem for us right now, we need to fill
the root object, but what should we fill
it with, well let's try first to just
do class1.create, that will be ok then we
at least would have one, so, when the action is executed it should
bring up ViewModel1, but the root of
ViewModel1 should be set to the
result of this expression class1.create
so what happens then refreshing the model and then it isn't
null anymore, so we're okay to wright here
and then that will show, right, but
we can do as many of these as we want
holding down ctrl, while I press
the action brings up another tab, so I
can do this one and that one and this one, etc
that won't help much, because there is
actually no way to see them all or
to open up perform with an existing class1 right
the only thing we can do is actually
just create new one in this view, so
normally all applications and
all system has some kind of repository
researcher, where you could find things
to start with and maybe you browse all
the things you have and you grab one of those
so let's do a view that is our browser
add a viewmodel and since it's
gonna be our browser, let's call it BrowserView
and give it the type Class1
and that's the only class we have currently
so why not and as add a nested view model class
we'd fast pick class1.allinstunces
what it does is generic column with class1.allinstunces
and it states something showing class1
soб change these expression to, what do we
have, we have attributes, like that
so this would be a good view to show
from the main menu, so, if we just stand
on it and say add a global action for
show what happens then is that this action was created
let's see, what it does actually what did
I do, I think the wrong thing and you want
to press ctrl+z for undo, I take it by
the menu, so you see what I do, undo and
then it disappeared, what I wanted to do
was to add not the class action for show
I wanted to add a global action for show
like that, so what it what happened was
show browser view it's named and then it
brings up the browser view and this one
doesn't have a root object expression
because it doesn't need one, because it
shows all class1 instances, so returning here and refreshing the model
and now show browser view, this one will
show al, since I restarted the system
with the model refresh, let's see
what happens if I press the one that creates, aaa, abb
then we see that there really are two objects
of class1 and we can change this one
here and see that they are realy the same
but then this was a limitation we really
want to be able to create things here
so, let's head back here and add
but I press this button action
definitions, that same action edit or
action definitions for shows, but it's
filtered on the view, I stand on and it
only shows the viewmodel actions and the
class actions that match, so this is
a good way to reduce the amount of
actions as they might be many/ yet
so what I want to do is to add a view
model action here and say that this one
can create new class1 object, like that
and the execute expression should just do what
we saw before class1.create
so if I refresh the model and show the browser view I have
a action that actually can create things
and now it shows on two levels and we'll
do the same thing, it's obvious here is
the only browser view level and also on
the allclass1 here, but I want to
opt that out because that is unnecessary and
so now we're on one object and we could
write something here what we want to do
now is to open up one of these in our
other view, so this one that we did that
first new global action, this one will
just create yet another one, see we have
no way currently to open up this one in this
well, if you really use the properties of
the prototype you can drag this one to
this green dot and then it will show it
so this is a way to change the root of
of the overview, like this and you can
see that it really changed
switch to object, like that, right, but and
we really want to add an action
available whenever we have class1 and
that kind of action is class actions
so new class action, class actions will always pop up whenever
you have a context of that class so
let's call this one create new, no
that wasn't what we wanted to do, what I am to do, it it's view class1
ok, that was what I wanted to do and that
this action should be on this class1, what should it do,
it should bring up the ViewModel1
in fact, let's rename the viewmodel1 to
let's call it the class1 object view
class1 object view, so it should
bring it up and now we have a chance to
set the road object, what we
want and what do we want
well we know that this is
class action, so it will only be in the context
of the class1 objects, so that would be
great just to set itself in this case
and the required type, required return type
is class1, because that is what
the form of you expect and the context is also class1
because that was the class that we
made an action for, so now we have a way to
let's do this again, model refresh
show browser view, now we're able to
this one is disabled, because there is
nothing selected, we can create one and
if I selected I can view it, also this
class action is in two places and I see
this here and that's because it's on
this level and since this is class1
even though it is not assigned,
it doesn't require a root object, but it also on this level
so this first level will always be null
also I will opt that out and refresh and show
browser view, so now I can create a new
class and when I select it
I can view that class and I can write
something and I can go back, like that, create
and view it and go back, like that,
so this is how you root and why you root windows or views
if, we were to check his model, we will get
some warnings and they are fairly long
let's see if I can get them on screen
so there's a new global action warning
the view model does not require root object
so this is just the information to help
us out doing the right thing, new global object
new global action, let's go to this one new global action
it brings up class1 object view
sets the view model root object, if we go to
this view, we see that we will
assign root today's but it hasn't
checked the check box requires root object
and that is what that warning is about
so, if I do that and head back and
check again, there's alone, super, so and
this is how basic navigation works when
you work with the MDriven and there
are a few other things you can do with
actions, but these, this is how you use
them for navigation, you state what the
view model to open up and what root object
if any it should have, of course we can do
few other things, so if we use the show
browser view or other, the view class1 object
let's take this one, it sets the root object to cell
but there's also an expression
execute expression on show and what it
will do is to execute this expression
whenever the view shows, so let's
experiment, self and we
in this case we will be in the context of
the sending, of the receiving form
so, the form  as vCurrent class1 object view
it's the root to the variable representing the root, but
we also have this strange variable vSender
that state context from their calling action
so this is actually this self
that since this is a class action
is a class1 so sender self and this
is what we set as the root, what if we
were to set attribute1 and we
would simply sign itself plus one, what
would happen then, refresh model, show
the browser, create a new one this is
empty, but as we selected and she was the
new one, it says one and if we go back
and show it again it says 11, because we have this
execute expression on show, what it is
what I'm supposed to use this for
well, maybe you have some variable that
you want to set, some context where you
come from that you want to set in the view
when you open it then this expression is great, but it does not in
any way replace the root object expression
the root object expression is
really important with working with view that are rooted
it's the only way to set the root on the object
well, as you know now it's not the only way
because you can also change
the root by draging to this dot and ok so
I'm going to wrap this up, feel free
to test these things out

Revision as of 22:00, 15 April 2017

In depth overview on how to navigate between views with actions and how root object expression works. You will find this pattern recurring over and over, while trying to solve real business problems. You will get the access to the data as we show the objects and navigate into various views for more detailed information. This skills help you develop efficient model infrastracture once it grows.

To make your experience more comfortable, we set the main tags mentioned in the video to the right bar menu of this mini player. Choose the interesting subtitle on the list and immediately get to the exact theme timeplace in the video. Now you can pick any topic to be instructed without watching the whole video.


Actions
    • global actions • ViewModel Action • class actions
ViewModel Root Object Create Repository Researcher Action Definitions Execute Expression Change the root of the View "VM does not require a root object" Execute expression OnShow
    vSender variable

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