Reusable SimpleDialog Bodies in Flutter

SimpleDialog(
    title: Text("My Simple Dialog"),
    children: [
        SimpleDialogOption(
            onPressed: () {
                // do something when this option is pressed
            },
            child: Text("Tap here!"),
        );
    ],
);

showDialog(context: context, builder: (BuildContext context) {
    return SimpleDialog(
        title: Text("My Simple Dialog"),
        children: [
            SimpleDialogOption(
                onPressed: () {
                    // do something when this option is pressed
                },
                child: Text("Tap here!"),
            )
        ],
    );
});

var response = await showDialog(context: context, builder: (BuildContext context) {
    return SimpleDialog(
        title: Text("Pick Someone"),
        children: [
            SimpleDialogOption(
                onPressed: () {
                    Navigator.pop(context, "Brad")
                },
                child: Text("Brad"),
            ),
            SimpleDialogOption(
                onPressed: () {
                    Navigator.pop(context, "Catherine")
                },
                child: Text("Catherine"),
            ),
        ],
    );
});

print(response);

GestureDetector(
    child: Icon(
        getIconUsingPrefix(name: "FA.envelope"),
        semanticLabel: "Email",
        size: 30),
    onTap: () async {
        var contact = await showDialog<SelectContactReturnType>(context: context, builder: (BuildContext context) {
        return SimpleDialog(
            title: Text("Send as Email to:"),
            children: [
                SelectContactDialogBody()
            ]);
        });
    // do something with contact
}),

import 'package:cloud_firestore/cloud_firestore.dart';
import 'package:flutter/material.dart';
import 'package:luna_journal/models/veterinarian.dart';
import 'package:luna_journal/viewmodels/veterinarians_vm.dart';
import 'package:provider/provider.dart';


/// SelectContactConfiguration is used to determine which contacts should be shown.
/// For example, if SelectContactConfiguration.SMS is chosen, we will only show contacts
/// that has an SMS number associated with them.
enum SelectContactConfiguration {
  SMS,
  EMAIL
}


/// This is kind of a weird type.
/// By boxing the Veterinarian, we add a third type that can help us determine
/// if the dialog was terminated early, or if an actual option was selected.
/// If we have a selectContactReturnType, then we can check the vet. If a vet is
/// provided, then one was selected. If vet is null, "Someone else" was selected.
/// Finally, if the selectContactReturnType is null, then the user terminated the
/// dialog choice.
class SelectContactReturnType {
  final Veterinarian vet;

  SelectContactReturnType({this.vet});
}

/// SelectContactDialogBody is the BODY of a simple dialog.
class SelectContactDialogBody extends StatelessWidget {
  final SelectContactConfiguration configuration;

  SelectContactDialogBody({this.configuration});

  @override
  Widget build(BuildContext context) {
    // Leverage Provider to get the veterinarian view model.
    var vetVm = Provider.of<VeterinariansViewModel>(context);

    return StreamBuilder(
        stream: vetVm.getVeterinariansStream(),
        builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
          // Probably want to handle this differently in production
          if (snapshot.hasError) {
            return new Text('Error: ${snapshot.error}');
          }
          switch (snapshot.connectionState) {
            case ConnectionState.waiting:
              return Center(
                child: CircularProgressIndicator(),
              );
            default:
              var entries = snapshot.data.docs
                  .map((e) =>
                  Veterinarian().fromFirebaseSnapshotDocument(e))
                  .toList();

              // Here we check the configuration to determine which elements to show
              // we filter out the ones that dont have the configuration-specified field.
              if (configuration == SelectContactConfiguration.EMAIL) {
                entries = entries.where((element) => element.email != "" && element.email != null).toList();
              } else {
                entries = entries.where((element) => element.phone != "" && element.phone != null).toList();
              }

              if (entries.isEmpty) {
                // empty container is fine here because we'll render the generic contact option below
                return Container();
              }

              return SizedBox(
                // This is kind of hacky, but just know that
                // you might have to specify a width and a height
                // especially if your listBuilder is contained inside
                // another scrollable view
                height: (entries.length * 40.0) + 40,
                width: 200,
                child: ListView.builder(
                    scrollDirection: Axis.vertical,
                    itemCount: entries.length + 1,
                    itemBuilder: (BuildContext context, int index) {
                      return SimpleDialogOption(
                        onPressed: () {
                          var response = SelectContactReturnType(vet: index < entries.length ? entries[index] : null);
                          Navigator.pop(context, response);
                        },
                        child: Text(index < entries.length ? entries[index].name : "Someone else"),
                      );
                    }),
              );
          }
        });
  }
}