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

    This page was created by Alexandra on 2017-01-08. Last edited by Edgar on 2025-01-20.

    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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