GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community. Already on GitHub? Sign in to your account. I have no constructor, and have no notion of a Key in the Widget.
I currently have never used Keynor do I understand when I would. StatelessWidget and StatefulWidget are fundamental building blocks for app developers so perhaps we should document them in slightly more tutorial fashion.
Maybe something like this:. A typical simple Stateless widget has a final field for each of its constructor parameters and a build method that returns external cladding widget tree which reflects the parameters' values.
The typical widget's constructor also accepts a key parameter. Callers may specify a Key to ensure that the widget's Element will be reused or a GlobalKey so that the widget's Element can be referred to later.
When should a widget's constructor not accept a key parameter? What is the impact if none of the widgets I have created so far take a Key? Should I refactor them to accept a Key? I'd recommend always accepting a key parameter except if the widget is private to the current library i. The impact is that if future code wants to associate a key with the widget, they'll either need to modify the widget to add the key parameter or they'll need to wrap the widget in another widget that does have a key.
Tracking the doc work here: Skip to content. Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. Sign up. New issue. Jump to bottom. Should I add a Key property to my custom widgets? Milestone 3: Current Milestone.Many people say that Flutter has a steep learning curve. If you have seen Flutter UI layout code like below simplified from hereyou may be inclined to agree with them.
Mountains are only steep if you climb straight up. And the Flutter learning curve is only hard if you try to do too much at once. Just as hiking trails with switchbacks makes a mountain climb more manageable, in this tutorial I will give you an opportunity to take some easy first steps to mastering Flutter.
You are going to discover that it's a lot easier than you thought. One of the first concepts that you encounter in Flutter are widgets, so we will be looking at what they are and how to use them. Most importantly, there will be lots of examples that you will be able to experiment with yourself. I encourage you to actually run the examples and make changes to them as you go through the tutorial.
This will greatly improve your rate of learning and help solidify your understanding of the topics. I hear and I forget. I see and I remember. I do and I understand. Attributed to Confucius even though he didn't really say it like that. I don't expect you to know much. That's the point of this tutorial. However, you should have already set up your development environment. Some people prefer Android Studio.
Others like Visual Studio Code because it's more lightweight. The fact is that both work fine. I'm writing the text of this tutorial using Visual Studio Code and running the code for the examples below in Android Studio with Flutter 1. If you haven't set up the Flutter development environment yet, then I highly recommend following the directions in the Flutter documentation.
Unlike a lot of documentation, the Flutter docs are very thorough and easy to follow. You should have finished at least the first three steps below but I highly recommend Step 4 as well.
Widgets are just pieces of your user interface. Text is a widget.NOTE: Original source here. About Testimonials Blog Sign Up. Core Concepts Integration tests test how pieces of your application work together as a whole. A typical integration test runs the actual app in an automated fashion and simulates the user interacting with the app. How Integration Tests Work in Flutter With an integration test, one bit of code will run or "drive" the actual app and another separate bit of code will simulate user interaction.
But not so fast, read on. Before We Continue Our tests will need to see if specific widgets exist with specific bits of text, such as a location name. How will be "find" these widgets then? What we will do is add a special property to certain widgets, called a "key". Understanding What Widget Keys Are Widgets can be uniquely identified in the "widget tree" by a "key". The "widget tree" is a hierarchical representation of a given screen in a Flutter app.
This tree structure allows Flutter to build a tree of widgets in memory. When Flutter needs to update specific parts of the UI, representing the UI as a "tree" makes it easy to do this.
Therefore, a "key" is a unique string associated with the widget. The "key" is effectively say, the equivalent to the "id" property of a in HTML.
Keys can be used to optimize the performance of an app in certain situations, but are generally optional. For our purposes, we can use a "key" that are tests can use as well. Here, you see we have another uniquely named key for the specific Text widget in our LocationTile. Implemeting our Integration Test We can now write our test, which will assume our app is already running via our "driver", implemented earlier in this tutorial.
We will fetch all locations and wait until the Locations screen is loaded. The test will do a basic check to see if the location list is loaded, by finding a widget by the key we defined in the previous step. We can configure a custom command in Visual Studio Code to run these tests but that's outside the scope of this tutorial, so we will run it via the command line.
Ensure you have flutter set in your PATH environment variable.There's a really good article on WaitBuyWhy about how the weeks in your life are like diamonds. Here I share some of my favourite shortcuts for Flutter development, so that I can save myself and everyone else a lot of time. Spend some time getting familiar with existing keymaps.
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Then, you can optimise your workflow and bind your own keys. It's totally worth it! Most stock widgets in Flutter have a lot of optional parameters, so keeping them in separate lines can be a big win. Creating a new widget? You can quickly import the required library without adding the import manually.
Similar to the above, use this to quickly add methods that are not yet implemented in a class. Also note the tabs on the left. Each one of these can be selected directly.
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Very useful for source code navigation. For example to return to previous scope after clicking through a method definition. This one is super useful in bigger projects or if you're new to a codebase.
Finds all usages of a given method or class:. To hide them entirely, you can use Distraction Free Mode. Hot Reloading in Flutter is awesome. I get the best of it by running my IDE and the Simulator side by side:. Want more? Flutter: My favourite keyboard shortcuts Jun 2, 6 min read. Motivation Life is short. Time is precious. Make the most of it. I'm happy when I'm coding in the zone. And I see my IDE as a powerful extension of my brain. Reformat Code with dartfmt Made changes to a source file and want to reformat code?
Say your indentation is a bit messy, like this: Fixing indentation by hand? Forget it. Automated and consistent formatting is just one shortcut away.
Hot Tips Adding a comma on the last parameter will format the code across multiple lines: Omitting the comma on the last parameter will keep the code inline: Most stock widgets in Flutter have a lot of optional parameters, so keeping them in separate lines can be a big win. Import library Creating a new widget? Implement methods Similar to the above, use this to quickly add methods that are not yet implemented in a class.
Generate Handy shortcut to generate common class methods and members.
The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. What are the possible reasons why a widget isn't found by key in a test, even if it's in the widget tree? If I just do:. The test fails because it finds too many widgets and doesn't know which one to tap. If I call debugDumpApp just before the call above, I can see that the Container with that key is actually in the widget tree:.
I tried making sure it's in view by calling ensureVisiblebut that also fails saying it can't find the widget. Learn more. Can't find widget by key even if it is in the tree Ask Question. Asked 3 days ago. Active 2 days ago. Viewed 16 times. If I just do: await tester. What am I doing wrong? SakoDaemon SakoDaemon 1 1 gold badge 5 5 silver badges 17 17 bronze badges. Active Oldest Votes.
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You will find links to the API docs on the pub page. For help getting started with Flutter, view our online documentation. For help on editing plugin code, view the documentation.
Alternatively, your editor might support flutter pub get. Check the docs for your editor to learn more. We analyzed this package on Apr 15,and provided a score, details, and suggestions below. Analysis was completed with status completed using:.
Add more detail to the description field of pubspec. Use 60 to characters to describe the package, what it does, and its target use case. Readme Changelog Example Installing Versions Getting Started For help getting started with Flutter, view our online documentation.
Depend on it Add this to your package's pubspec. Health: Code health derived from static analysis. Maintenance: Reflects how tidy and up-to-date the package is. Overall: Weighted score of the above. Learn more about scoring. The package description is too short. Popularity: Describes how popular the package is relative to other packages.Flutter is a cross-platform language that works on both Android and iOS.
This means that it will draw buttons, text, checkboxes and other items with whatever widget you are using. Most Flutter tutorials and demos use MaterialApp and Scaffold widgets. You can use the platform call, Platform. However, if you start to do that, your code will become littered with if Platform.
Download the starter project for this tutorial by using the Download Materials button at the top or bottom of the page. This tutorial will use Android Studio with the Flutter extension. To install the Flutter plugin, go to the Preferences dialog of Android Studio and find the Plugins section. Click on the Marketplace tab and type Flutterthen click the Install button. You may also need to install other plugins, like Dart.
Open the starter project in Android Studio by choosing Open an existing Android Studio project and finding the root folder of the starter project zip file:. Open the pubspec. Now, select either the Android emulator or the iOS simulator. Each screen only has a colored square to show the screen changes. If you want to use these, you have to build them yourself. When you create a new Flutter app, it automatically adds a MaterialApp widget as the top-level widget.
This is the Material version of WidgetsAppwhich wraps several widgets that your apps will need to work. This sets the routing and themes. Open up main. Go ahead and delete the theme and title now. The Platform library uses separate theme classes for both Android and iOS. Go ahead and add some theme code that you can use with PlatformApp by adding this code at the top of main.