Nullable | source code only package which allows you to use .NET
kandi X-RAY | Nullable Summary
kandi X-RAY | Nullable Summary
:running: Quickstart | :books: Guides | :package: NuGet. With the release of C# 8.0, support for nullable reference types has been added to the language. Futhermore, .NET Core 3.0 added new nullable attributes like the AllowNullAttribute which are sometimes required to exactly declare when and how null is allowed in specific code sections. Unfortunately, these attributes are not available in older target frameworks like .NET Standard 2.0 which makes annotating existing code harder. Luckily, this problem can be solved by re-declaring the attributes as internal classes - the C# compiler will still use them for generating warnings, even though the target framework doesn't support these attributes by itself. This repository hosts the code for the "Nullable" NuGet Package which, when referenced, adds support for these attributes. The code for these attributes is added at compile time and gets built into the referencing project. This means that the resulting project does not have an explicit dependency on the Nullable package, because the attributes are not distributed as a library. Futhermore, the code only gets added to the project if the nullable attributes are not already supported by the target framework. The images below show an example - in the library which targets .NET Standard 2.0, the attributes have been added during the compilation. That is not the case for the library targeting .NET Standard 2.1, because the attributes are available through the .NET BCL there. This allows you to easily multi-target your projects without having to change a single line of code.
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Community Discussions
Trending Discussions on Nullable
QUESTION
My app consists in letting you add lists in which you can keep your notes. Therefore, I have this NotesListActivity where I can add and keep my Lists. I wanted to filter this lists following the https://www.youtube.com/watch?v=CTvzoVtKoJ8 tutorial and then I tried to adapt it to my code like below. Could you please tell me what is the problem here, cause I don't even get an error, I just not get any title of list as result. So, this is what I have in my RecyclerAdapter:
...ANSWER
Answered 2021-Jun-13 at 20:18The problem is that you are using an empty notesListAll list for filtering results; you need to populate it with the list of notes in the constructor
QUESTION
I have the following two interfaces, one which allows a nullable vin, the other that doesn't:
ANSWER
Answered 2021-Jun-15 at 18:49You can use a type predicate to define a user-defined type guard like this:
QUESTION
First migration file:
ANSWER
Answered 2021-Jun-15 at 18:27change the posts migration post_id and author_id to this :
QUESTION
I'm doing a Group Chat with Firebase and currently I'm using a RecyclerView to display chat messages and I'm having a problem. When you open the app in the fragmented home and you go to chat activity and start chatting (adding elements to recycler view) all goes fine. But, when you go via the NavigationDrawer to another fragment and get back to the chat fragment using again this Navigation Drawer. When you add one element in the chat it appears all in the blank it just displays the last message. Anybody knows why does this happens?
Here I leave the RecyclerView Adapter Code:
...ANSWER
Answered 2021-Jun-15 at 13:55To solve your problem you can just remove the OnResume method because you are initializing the array every time you change between fragments and that is the problem.
QUESTION
I have a dataframe whose printSchema gives this schema :
...ANSWER
Answered 2021-Jun-15 at 12:31You can create the schema as below
QUESTION
So I am relatively new to programming, and I have been working on this task app, where I want to save the data such as task name and more, given by the user. I am trying to accomplish this using Room. Now, initially, when I tried to do it, the app would crash since I was doing everything on the main thread probably. So, after a little research, I came to AsyncTask, but that is outdated. Now finally I have come across the Executer. I created a class for it, but I am a little unsure as to how I can implement it in my app. This is what I did :
Entity Class :
...ANSWER
Answered 2021-Jun-14 at 12:03First make a Repository class and make an instance of your DAO
QUESTION
I'm having a problem with altering the value of a mutable map. I assume it's something to do with nullable types, but I'm not sure. The code producing the error is below:
...ANSWER
Answered 2021-Jun-15 at 08:46The statement map.getValue(num) += 1 is not allowed because the += operator is only defined in 2 cases:
- a plusAssign() operator is defined on the left operand's type (not the case for
Int) - a plus() operator is defined on the left operand's type AND the left operand is a variable. In this case
+=reassigns the variable on the left witholdValue.plus(the right operand).
The compiler tries to consider case #2 here because Int.plus(Int) is defined, but the left operand is not a variable so it fails with the error message you mentioned.
You can't write this for the same reasons you can't write map.getValue(num) = 42.
The correct way of mutating a value in a map is either via the set operator (like you did earlier with the syntax sugar map[num] = 0), or via other mutating functions like merge.
In your case, merge is nice because it can remove the special case altogether (it's only available on the JVM target though):
QUESTION
Since an upgrade to Oracle.EntityFrameworkCore 5.21.1 running an "Add-Migration" command produces a migration which creates a table for the entity that is mapped to a view. The view was created before the upgrade of the library and different migration was generated before the upgrade as well, and there was no table creation, so I'm pretty sure it's something to do with the upgrade of the package itself.
My question is am I doing something wrong here, or did I miss something in the new EF Core release. Or is it simply a bug
The entity in question is a simple POCO
...ANSWER
Answered 2021-Jun-15 at 06:16The issue was actually a breaking change for the new version of EF Core 5.0, which I apparently looked over. https://docs.microsoft.com/en-us/ef/core/what-is-new/ef-core-5.0/breaking-changes#toview
QUESTION
I'm just working through this whole null-safety mode with my Flutter project and unsure what the difference is with ? and ! in calls to object methods.
For example, the hint was to add a ! conditional. Here's an example I have right now, and I'm unsure if this should be a ? or a ! at the findNbr!.replaceAll().
ANSWER
Answered 2021-Jun-15 at 05:46I would like to advice you to use the ! operator, also the called bang operator, as little as possible. You should only use this operator when the dart analyser is wrong and you know for 100% that the value will never be null.
Below is an example of where the dart analyser would be wrong and you should use the bang operator.
QUESTION
I'm new to android studio and i'm not sure what was going on with it. How can I solve this error?
In the logcat, it mentioned that I required a view for recycler_food_list which apparently I had already coded into the foodlistfragment.java.
Logcat
...ANSWER
Answered 2021-Jun-15 at 03:29You're doing inflater.inflate(R.layout.fragment_menu, container, false);, not inflating your R.layout.fragment_food_list. You'll need to inflate the right layout to find your Recycler view.
Community Discussions, Code Snippets contain sources that include Stack Exchange Network
Vulnerabilities
No vulnerabilities reported
Install Nullable
Reference the package Add the package to your project, for example via: Install-Package Nullable --or-- dotnet add package Nullable
Ensure that the package has been added as a development dependency Open your .csproj file and ensure that the new package reference looks similar to this: <PackageReference Include="Nullable" Version="<YOUR_VERSION>"> <PrivateAssets>all</PrivateAssets> <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets> </PackageReference> <!-- This style also works, but is not automatically used by .NET: --> <PackageReference Include="Nullable" Version="<YOUR_VERSION>" PrivateAssets="all" /> This is especially important for libraries that are published to NuGet, because without this, the library will have an explicit dependency on the Nullable package.
Build the project Ensure that the project compiles. If a build error occurs, you will most likely have to update the C# language version (see next step).
Enable Nullable Reference Types Still in your .csproj file you need to activate the feature to fully use it. The following activation sample is what seems to be the most common use case. But do not hesitate to look at my guides for other considerations. <PropertyGroup> <!-- Your desired target frameworks. --> <TargetFrameworks>net472;netstandard2.0;netstandard2.1;netcoreapp3.0</TargetFrameworks> <!-- The C# language version to use. Must be at least 8.0 (other suggestions: 9.0, latest, preview).--> <LangVersion>8.0</LangVersion> <!-- or --> <LangVersion>latest</LangVersion> <!-- Enable nullable reference types. You can also use "annotations" instead of "enable" to prevent the compiler from emitting warnings. --> <Nullable>enable</Nullable> </PropertyGroup>
For WPF users: There have been issues with WPF projects in the past which resulted in compilation errors, however these have been fixed with the .NET 5.0.102 SDK. To get Nullable working with your WPF project, ensure that you are using an SDK >= 5.0.102 SDK and then add the following configuration to your .csproj file: <UseWPF>true</UseWPF> <IncludePackageReferencesDuringMarkupCompilation>true</IncludePackageReferencesDuringMarkupCompilation>
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