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I'm starting on Flutter, I have this error that appeared from the moment I created a SliverPersistentHeader. I tried to find an explanation but nothing.

Does the error come from the Sliver ?

I don't have the error regularly but I have to save my work 2 times in a row to have a normal display otherwise the error comes back

Also, is it simply an error when debugging or could it be displayed in the eyes of users ?

My page:

I am not sure how to best describe this (I am sure there is a more proper way of describing it).

I have a large dataset full of house details (eg. walls, bathrooms, bedrooms, etc.) that I need to analyze and rank based on their characteristics. I have created a ranking system with "4" being the best and "0" being the worst, for example, a house with 1 bedroom may get a "0" for their bedroom score but a house with a 3 bathrooms may get a "4" for their bathroom score.

Once I assocaite the ranks to all the characteristics, I plan on creating a weighted average to see which houses are the best.

How is the best way to do this? I need to do this about 20 times (for 20 characteristics) and so far this is the only way I know how to do it-- and it is quite tedious, especially if I ever need to go back and change anything.

Also, would be good to better understand how the df.loc function works, I was able to do make it work but I don't quite understand it.

I am trying to build a gridview nested in a listview with flutter, based on the attached minimal viable example, while trying to leverage the inner gridviews cacheExtent feature, which shall prevent items to be built all at once. In the full application i do kind of heavy stuff, so i want as few items to be loaded at the same time as possible, but unfortunately it looks like cacheExtent is ignored for the inner list, when nesting multiple list. For the surrounding list cacheExtent works as expected.

Does anyone have a solution for this and can explain me, while it won't work for the inner list? I am not only looking for a copy&paste solution, i am really trying to understand whats going on in flutter here, since i guess it is caused by any fundamental layouting policy which i don't know yet.

Environment:

• Can't define the 'const' constructor because the field 'currentUser' is initialized with a non-constant value.
• Can't define a const constructor for a class with non-final fields.
• The argument type 'Stream>>' can't be assigned to the parameter type 'Widget Function(BuildContext, AsyncSnapshot>)'.
• The argument for the named parameter 'builder' was already specified.
• The body might complete normally, causing 'null' to be returned, but the return type is a potentially non-nullable type.

how to solve this error. appriciate your help on this.

people.dart

I have added 'Sliver AppBar' into Scaffold of my app and I am wondering why it shows two app bars now. The Scaffold contains only one drawer but in UI , it shows two drawers. Anybody know what is going wrong.

I'm trying to make a UI in flutter wherein I'm using SliverAppBar(I mention this because I need to use either CustomScrollView or NestedScrollView) and now in the body, I was to make the first two elements not scroll when they reach the top of the screen while the bottom list does. Using CustomScrollView, it either scrolls as a whole or does not at all(Appbar included). In NestedScrollView, if i use NeverScrollableScrollPhysics, the appbar scrolls and the body does not. Now I can either make the whole body scrollable or i get a pixel error. Please help me.

I have added the NestedScrollView code below. I need the search bar and the go to cart container to get fixed at the top once the sliver bar disappears.

I was learning from another project and when I tried to implement it I have the following errors:

Error: The argument type 'IconData' can't be assigned to the parameter type 'Widget'.

Any help?

My code is the following:

I want to implement a Staggered GridView, because my SliverGrid delegate requires an aspect ratio, and I want the grid items to be dynamically sized which is only possible with staggered gridview as far as I know.

My question is how can I implement a staggered gridview and use it in my CustomScrollView as a sliver?

Edit:

My pubspec.yaml file:

I need to create a custom sliver app bar that will shrink when the user starts scrolling. The extended app bar will have two distinct features:

1. Background Image
2. Tab Bar

Expected sliverappbar before scroll:

As, the user starts to scroll the appbar will become the default AppBar provided by flutter

This is what I have done till now. And the code is: