if I change a value of some prop inside `@Model` o...

# compose

[Bruno_]

if I change a value of some prop inside @Model object, will it trigger rerender of a whole "tree"? I mean not only the composable that uses this object, right?

[Luca Nicoletti]

@Model observes only variables, not constants. If a property is constant, what’s the point in observing it? It will never change

[Andrey Kulikov]

there is a special observable list implementation - modelListOf<Foo>()

[Muh Rahmatullah]

but the case of using mutableList with val, the value inside of the list could change

[Muh Rahmatullah]

okay, will look into it

[Luca Nicoletti]

@Muh Rahmatullah if the Foo is also a Model it should work

[Luca Nicoletti]

Only if Foo changes as you said

[Muh Rahmatullah]

@Luca Nicoletti I tried that too but it’s not working as well

[Andrey Kulikov]

no, it will not work with just mutableList and Model annotated Foo, as there is no changes within Foo, it is a new item added into the list

[Muh Rahmatullah]

tried the modelListOf and the recompose process now works, thanks @Andrey Kulikov @Luca Nicoletti

[Luca Nicoletti]

@Andrey Kulikov That’s what I said:

Only if Foo changes

[Luca Nicoletti]

if

the value inside of the list could change

if it does change, the @Composable which refers to the specific instance of Foo will be drawn again, right?

[Andrey Kulikov]

yes, the composable using specific Model annotated class instance will be automatically recomposed(this will trigger all the required remeasuring/redrawing). if you use it inside measuring lambda - it will be remeasured. if you use inside drawing lambda - redrawn

[Luca Nicoletti]

🙂 Thanks

[Leland Richardson [G]]

Note thate you don’t need ModelList if you just use an immutable list pattern, and instead of using MutableList with add, you could use List with plus (list concatenation)

[Leland Richardson [G]]

@Model will observe assignments to the property itself, but not mutations in the object that is the property (MutableList in your case)

[Muh Rahmatullah]

thanks @Leland Richardson [G]