The error occurs because AppBar
expects a widget that implements the PreferredSizeWidget
interface, but Consumer<NoteModel>
does not directly implement this interface. To solve this, you need to return an AppBar
from within the Consumer
builder method.
Here’s how you can do it:
Scaffold(
appBar: PreferredSize(
preferredSize: Size.fromHeight(kToolbarHeight),
child: Consumer<NoteModel>(
builder: (context, noteModel, child) {
return AppBar(
title: Text(
'Your Title',
style: TextStyle(
color: noteModel.isPrivate ? Colors.red : Colors.green,
),
),
);
},
),
),
body: // Your other widgets,
);
In this approach, I wrapped the Consumer<NoteModel>
inside a PreferredSize
widget to ensure it adheres to the PreferredSizeWidget
interface required by appBar
.
This should resolve the error while allowing you to update only the AppBar
based on changes in your NoteModel
.
Glory to ChatGPT!
set -x && if cd flutter; then git pull && cd .. ; else git clone https://github.com/flutter/flutter.git; (cd flutter && git fetch --tags && git checkout 3.22.3); fi && ls && flutter/bin/flutter doctor && flutter/bin/flutter clean && flutter/bin/flutter config --enable-web && cp .env.production .env && sed -i "s/VERSION_PLACEHOLDER/`git rev-parse --short HEAD`/" .env && flutter/bin/flutter build web --web-renderer html --base-href="/" --release
In C#, both FirstOrDefault
and SingleOrDefault
are LINQ methods that operate on collections, but they serve different purposes:
FirstOrDefault
-
Purpose: Returns the first element in a collection that satisfies a specified condition, or the default value for the type if no such element is found.
-
Behavior:
- If the collection contains multiple elements that satisfy the condition, it returns the first one.
- If no elements satisfy the condition, it returns the default value (
null
for reference types, 0
for numeric types, etc.).
-
Use Case: When you're interested in getting the first match or a default value if none exist, and you don't care if there are multiple matches.
SingleOrDefault
-
Purpose: Returns the single element in a collection that satisfies a specified condition, or the default value for the type if no such element is found.
-
Behavior:
- If the collection contains exactly one element that satisfies the condition, it returns that element.
- If no elements satisfy the condition, it returns the default value.
- If more than one element satisfies the condition, it throws an
InvalidOperationException
because the expectation is that there should be exactly one match.
-
Use Case: When you're expecting either one or zero matches, and multiple matches would indicate an error in your data or logic.
Summary
FirstOrDefault
: Use when you want the first matching element or a default value, and multiple matches are acceptable.
SingleOrDefault
: Use when you expect exactly one matching element or a default value, and multiple matches are an error.
--- a/lib/services/note_tag_service.dart
+++ b/lib/services/note_tag_service.dart
@@ -9,6 +9,5 @@ class NoteTagService {
Future<Map<String, int>> getMyTagCloud() async {
var apiResult = (await _noteTagApi.getMyTagCloud()).data;
if (!apiResult['successful']) throw ApiException(apiResult);
- return apiResult['data'].map((item) => {item['tag'] as String: item['count'] as int});
- }
+ return { for (var item in apiResult['data']) item['tag'] as String : item['count'] as int }; }
+ }
I found this brilliant answer at Stack overflow. It is way more clearer and useful than Microsoft's official one
You can use inline modifiers as follows:
// case insensitive match
Regex MyRegex = new Regex(@"(?i)[a-z]+"); // case insensitive match
or, inverse the meaning of the modifier by adding a minus-sign:
// case sensitive match
Regex MyRegex = new Regex(@"(?-i)[a-z]+"); // case sensitive match
or, switch them on and off:
// case sensitive, then case-insensitive match
Regex MyRegex = new Regex(@"(?-i)[a-z]+(?i)[k-n]+");
Alternatively, you can use the mode-modifier span syntax using a colon :
and a grouping parenthesis, which scopes the modifier to only that group:
// case sensitive, then case-insensitive match
Regex MyRegex = new Regex(@"(?-i:[a-z]+)(?i:[k-n]+)");
You can use multiple modifiers in one go like this (?is-m:text)
, or after another, if you find that clearer (?i)(?s)(?-m)text
(I don't). When you use the on/off switching syntax, be aware that the modifier works till the next switch, or the end of the regex. Conversely, using the mode-modified spans, after the span the default behavior will apply.
Finally: the allowed modifiers in .NET are (use a minus to invert the mode):
x
allow whitespace and comments
s
single-line mode
m
multi-line mode
i
case insensitivity
n
only allow explicit capture (.NET specific)