How to set minimum height of SliverAppBar within NestedScrollView in Flutter

This is Actually an requested Feature - https://github.com/flutter/flutter/issues/21298

A work Around is to use Bottom

SliverAppBar(              // this is where I would like to set some minimum constraint              expandedHeight: 300,              floating: false,              pinned: true,              bottom: PreferredSize(                       // Add this code                preferredSize: Size.fromHeight(60.0),      // Add this code                child: Text(''),                           // Add this code              ),                                           // Add this code              flexibleSpace: Container(                padding: EdgeInsets.all(10),                height: 340,                width: double.infinity,                child: Column(                  mainAxisAlignment: MainAxisAlignment.end,                  crossAxisAlignment: CrossAxisAlignment.start,                  children: <Widget>[                    Container(                      height: 40,                    ),                    Container(                      height: 60,                    ),                    Expanded(child: Container()),                    Text('TEST'),                  ],                ),                decoration: BoxDecoration(                    image: DecorationImage(                        image: NetworkImage('https://picsum.photos/400/400'),                        fit: BoxFit.cover)),              ),            )

I don't know since exactly when, but as of now, you can also use the collapsedHeight property, documented as below:

https://api.flutter.dev/flutter/material/SliverAppBar/collapsedHeight.html

Currently I am on flutter 1.20.1 and I have this property available.

Your code also works fine after decreasing the size from container .

 SliverAppBar( // this is where I would like to set some minimum constraint          expandedHeight: 300,          floating: false,          pinned: true,          flexibleSpace: Container(            padding: EdgeInsets.all(10),            height: 340,            width: double.infinity,            child: Column(              mainAxisAlignment: MainAxisAlignment.end,              crossAxisAlignment: CrossAxisAlignment.start,              children: <Widget>[                Container(                  height: 10,  //decreas the size                ),                Container(                  height: 10, //decrease the size                ),                Expanded(child: Container()),                Text('TEST'),              ],            ),            decoration: BoxDecoration(                image: DecorationImage(                    image: NetworkImage('https://picsum.photos/400/400'),                    fit: BoxFit.cover)),          ),        )