AlexDresko.com

Entity Framework Core Navigation Property vs Foreign Key Property — FIGHT!

Suppose we have an entity A that has a direct, 1:1, relationship with entity B. So…

class A {
    public int Id { get; set; }
    public BId { get; set; }
    public B B { get; set; }
}

class B {
    public int Id { get; set; }
}

What happens if we try to assign two different Bs to an A like this?

var b1 = new B();
var b2 = new B();

var a = new A { 
    BId = b1,
    B = b2
};

context.A.Add(a);
context.SaveChanges();

b1 wins. A.B is set to b1 and A.BId is set to b1.Id.

How did I know that? I wrong a bunch of unit tests to find out. I couldn’t find it documented anywhere and my lack of understanding what seriously hindering my ability to use EF properly.

Here are the rules I came up with:

In general, setting the foreign key property always trumps setting the navigation property. The only exception to the rule is when you set the foreign key property to null and the navigation property to a valid entity when the parent entity is already associated with a child entity. See ForeignKeySmarts11 below.
When editing an entity, you only need to set the foreign key property or the navigation property. When you call SaveChanges, the property you didn’t set will be synchronized with the property that you did set. Setting both properties is fine, and in some cases may be the preference if you need to interrogate the properties before calling SaveChanges.

Given the strange quirk in rule #1, I recommend always setting the foreign key property and only the foreign key property if possible.

At this point, I’ll shut up and just show you the tests. Some details within the test have been removed to make them easier to read.

[Test]
public async Task ForeignKeySmarts1()
{
    var b = await AddB("Something");

    var a = await AddA(new A { Name = "Yum", B = b.Entity });

    Assert.That(a.Entity.B, Is.Not.Null);
    Assert.That(a.Entity.B?.Id, Is.EqualTo(b.Entity.Id));
}


[Test]
public async Task ForeignKeySmarts3()
{
    var b = await AddB("Something");

    var a = await AddA(new A { Name = "Yum", BId = b.Entity.Id });

    Assert.That(a.Entity.B, Is.Not.Null);
    Assert.That(a.Entity.B?.Id, Is.EqualTo(b.Entity.Id));
}

[Test]
public async Task ForeignKeySmarts4()
{
    var b1 = await AddB("Something");

    var a = await AddA(new A { Name = "Yum", BId = b1.Entity.Id });

    var b2 = await AddB("Another");

    a.Entity.B = b2.Entity;
    await _context.SaveChangesAsync();

    Assert.That(a.Entity.B.Id, Is.EqualTo(b2.Entity.Id));
    Assert.That(a.Entity.B.Name, Is.EqualTo(b2.Entity.Name));
}

[Test]
public async Task ForeignKeySmarts5()
{
    var b1 = await AddB("Something");

    var a = await AddA(new A { Name = "Yum", BId = b1.Entity.Id });

    var b2 = await AddB("Another");

    a.Entity.BId = b2.Entity.Id;
    await _context.SaveChangesAsync();

    Assert.That(a.Entity.B?.Id, Is.EqualTo(b2.Entity.Id));
    Assert.That(a.Entity.B?.Name, Is.EqualTo(b2.Entity.Name));
}

[Test]
public async Task ForeignKeySmarts10()
{
    var b1 = await AddB("Something");

    var a = await AddA(new A { Name = "Yum", BId = b1.Entity.Id });

    var b2 = await AddB("Another");

    a.Entity.BId = b2.Entity.Id;
    a.Entity.B = null;

    await _context.SaveChangesAsync();

    Assert.That(a.Entity.B?.Id, Is.EqualTo(b2.Entity.Id));
    Assert.That(a.Entity.B?.Name, Is.EqualTo(b2.Entity.Name));
}

[Test]
public async Task ForeignKeySmarts11()
{
    var b1 = await AddB("Something");

    var a = await AddA(new A { Name = "Yum", BId = b1.Entity.Id });

    var b2 = await AddB("Another");

    a.Entity.BId = null;
    a.Entity.B = b2.Entity;

    await _context.SaveChangesAsync();

    Assert.That(a.Entity.B?.Id, Is.EqualTo(b2.Entity.Id));
    Assert.That(a.Entity.B?.Name, Is.EqualTo(b2.Entity.Name));
}

[Test]
public async Task ForeignKeySmarts6()
{
    var b1 = await AddB("Something");

    var a = await AddA(new A { Name = "Yum", BId = b1.Entity.Id });

    var b2 = await AddB("Another");
    var b3 = await AddB("Dawg");

    a.Entity.BId = b2.Entity.Id;
    a.Entity.B = b3.Entity;

    await _context.SaveChangesAsync();

    Assert.That(a.Entity.B?.Id, Is.EqualTo(b2.Entity.Id));
    Assert.That(a.Entity.B?.Name, Is.EqualTo(b2.Entity.Name));
}

[Test]
public async Task ForeignKeySmarts7()
{
    var b1 = await AddB("Something");

    var a = await AddA(new A { Name = "Yum", BId = b1.Entity.Id });

    var b2 = await AddB("Another");
    var b3 = await AddB("Dawg");

    a.Entity.BId = b3.Entity.Id;
    a.Entity.B = b2.Entity;

    await _context.SaveChangesAsync();

    Assert.That(a.Entity.B?.Id, Is.EqualTo(b3.Entity.Id));
    Assert.That(a.Entity.B?.Name, Is.EqualTo(b3.Entity.Name));
}

[Test]
public async Task ForeignKeySmarts2()
{
    var b1 = await AddB("Something");
    var b2 = await AddB("Another");

    var a = await AddA(new A { Name = "Yum",
        B = b1.Entity,
        BId = b2.Entity.Id
    });

    Assert.That(a.Entity.B, Is.Not.Null);
    Assert.That(a.Entity.B?.Id, Is.GreaterThan(0));
    Assert.That(a.Entity.B?.Id, Is.EqualTo(b2.Entity.Id));
    Assert.That(a.Entity.B?.Name, Is.EqualTo(b2.Entity.Name));
}

[Test]
public async Task ForeignKeySmarts8()
{
    var b1 = await AddB("Something");
    var b2 = await AddB("Another");

    var a = await AddA(new A { Name = "Yum",
        B = b2.Entity,
        BId = b1.Entity.Id
    });

    Assert.That(a.Entity.B, Is.Not.Null);
    Assert.That(a.Entity.B?.Id, Is.GreaterThan(0));
    Assert.That(a.Entity.B?.Id, Is.EqualTo(b1.Entity.Id));
    Assert.That(a.Entity.B?.Name, Is.EqualTo(b1.Entity.Name));
}

[Test]
public async Task ForeignKeySmarts9()
{
    var b2 = await AddB("Another");
    var b1 = await AddB("Something");

    var a = await AddA(new A { Name = "Yum",
        B = b2.Entity,
        BId = b1.Entity.Id
    });

    Assert.That(a.Entity.B, Is.Not.Null);
    Assert.That(a.Entity.B?.Id, Is.GreaterThan(0));
    Assert.That(a.Entity.B?.Id, Is.EqualTo(b1.Entity.Id));
    Assert.That(a.Entity.B?.Name, Is.EqualTo(b1.Entity.Name));
}

/// <param name="intelligencePoint"></param>
private async Task<EntityEntry<A>> AddA(A intelligencePoint)
{
    var a = await _context.As.AddAsync(intelligencePoint);
    await _context.SaveChangesAsync();
    return a;
}

/// <param name="name"></param>
private async Task<EntityEntry<B>> AddB(string name)
{
    var b = await _context.Bs.AddAsync(new B { Name = name });
    await _context.SaveChangesAsync();
    return b;
}

[Test]
public async Task ForeignKeySmarts12()
{
    var b1 = await AddB("Something");
    var b2 = await AddB("Another");

    var a = await AddA(new A { Name = "Yum", BId = b1.Entity.Id, B = b2.Entity});

    Assert.That(a.Entity.B?.Id, Is.EqualTo(b1.Entity.Id));
    Assert.That(a.Entity.B?.Name, Is.EqualTo(b1.Entity.Name));
}

[Test]
public async Task ForeignKeySmarts13()
{
    var b1 = await AddB("Something");
    var b2 = await AddB("Another");

    var a = await AddA(new A { Name = "Yum", BId = b1.Entity.Id});

    a.Entity.B = b2.Entity;
    await _context.SaveChangesAsync();

    Assert.That(a.Entity.B?.Id, Is.EqualTo(b2.Entity.Id));
    Assert.That(a.Entity.B?.Name, Is.EqualTo(b2.Entity.Name));
}

[Test]
public async Task ForeignKeySmarts14()
{
    var b1 = await AddB("Something");

    var a = await AddA(new A { Name = "Yum", BId = b1.Entity.Id});

    a.Entity.B = new B
    {
        Name = "cow"
    };

    await _context.SaveChangesAsync();

    Assert.That(a.Entity.B?.Id, Is.Not.EqualTo(b1.Entity.Id));
    Assert.That(a.Entity.B?.Name, Is.Not.EqualTo(b1.Entity.Name));
}

[Test]
public async Task ForeignKeySmarts15()
{
    var b1 = await AddB("Something");

    var a = await AddA(new A { Name = "Yum", BId = b1.Entity.Id});

    a.Entity.BId = null;

    await _context.SaveChangesAsync();

    Assert.That(a.Entity.B?.Id, Is.Null);
    Assert.That(a.Entity.B?.Name, Is.Null);
}

[Test]
public async Task ForeignKeySmarts16()
{
    var b1 = await AddB("Something");

    var a = await AddA(new A { Name = "Yum", BId = b1.Entity.Id});

    a.Entity.B = null;

    await _context.SaveChangesAsync();

    Assert.That(a.Entity.B?.Id, Is.Null);
    Assert.That(a.Entity.B?.Name, Is.Null);
}

HtmlWebpackPlugin + ASP.NET Core 3

The idea

My goal with this experiment was to set up a Razor page that was generated from HtmlWebpackPlugin in ASP.NET Core 3.

In other words, I want webpack to generate my controller view (.cshtml file) because it has a better understanding of what the client code should look like. At the same time, I wanted the full power of ASP.NET Core in my Razor files.

I spent far too many hours trying to get this to work to not share my solution with the world.

The full code for this experiment is at https://github.com/alexdresko/htmlwebpackplugin-aspnetcore3

webpack config

The webpack.config.js file is simple enough. Note the template, inject, and filename options for HtmlWebpackPlugin. template is relative to webpack.config.js, and filename is relative to the output folder.

const path = require('path');
const { CleanWebpackPlugin } = require('clean-webpack-plugin');
const HtmlWebpackPlugin = require('html-webpack-plugin');

module.exports = {
    entry: { index: './src/index.js' },
    mode: 'development',
    output: {
        filename: '[name].[hash].bundle.js',
        path: path.resolve(__dirname, 'wwwroot/dist'),
        publicPath: '/dist'
    },
    plugins: [
        new CleanWebpackPlugin(),
        new HtmlWebpackPlugin({
            template: './Views/Home/Index.ejs',
            filename: '../../Views/Home/Index.cshtml',
            inject: false,
            minify: false,
        })
    ]
};

The html-webpack-plugin template

The index.ejs file is pretty simple. Notice how I’m using both Razor functionality (setting the layout at the top of the page), and ejs functionality (definitely see the plugin documentation for more on that)

@using System.IO

@{
Layout = "";
}
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8">
    <title><%= htmlWebpackPlugin.options.title || 'Webpack App'%></title>

    <% for (var css in htmlWebpackPlugin.files.css) { %>
    <link href="<%= htmlWebpackPlugin.files.css[css] %>" rel="stylesheet">
    <% } %>
</head>

<body>
    <h1>TADA!</h1>
	<p>If you didn't see a popup, it didn't work</p>
	<h2>Expected</h2>
	<ol>
	<% for (var chunk in htmlWebpackPlugin.files.chunks) { %>
	    <li><%= htmlWebpackPlugin.files.chunks[chunk].entry %></li>
    <% } %>
    </ol>

	<h2>Actual</h2>
	<ol>
	    @{
	        foreach (var file in Directory.GetFiles("./wwwroot/dist"))
	        {
	            <li>@file</li>
	        }
	    }
    </ol>

	<% for (var chunk in htmlWebpackPlugin.files.chunks) { %>
    <script src="<%= htmlWebpackPlugin.files.chunks[chunk].entry %>"></script>
    <% } %>

    <% if (htmlWebpackPlugin.options.devServer) { %>
    <script src="<%= htmlWebpackPlugin.options.devServer%>/webpack-dev-server.js"></script>
    <% } %>
</body>

</html>

On the server side

This page has some very important information. Namely:

Runtime compilation is enabled using the Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation package. To enable runtime compilation, apps must:
Install the Microsoft.AspNetCore.Mvc.Razor.RuntimeCompilation NuGet package.
Update the project’s Startup.ConfigureServices method to include a call to AddRazorRuntimeCompilation

With that information in hand, I added AddRazorRuntimeCompilation()to startup.cs:

services.AddRazorPages()
                .AddRazorRuntimeCompilation();

Justification

To prove why all of this is good, consider the typical approach for including webpack files into a Razor page:

<script type="text/javascript" asp-src-include="~/dist/app*.chunk.js"
                                  asp-src-exclude="~/dist/app*.async*.chunk.js"></script>

Then remember that webpack is going to put new files into the dist folder every time you build your application. By default, webpack will not clean your dist folder, and we’ve configured webpack to output our files as “[name].[hash].bundle.js”. If you’ve built your application 100 times, the <script> tag above is going to insert your javascript files 100 times!

Granted, you could just install and configure clean-webpack-plugin to clean your dist folder as part of the build, but that’s not the point. The point again is that html-webpack-plugin is smarter than ASP.NET about how the client code should look. There’s a rich ecosystem of plugins and options available for html-webpack-plugin, and many front end frameworks go to great lengths to ensure their compatibility.

It works!

Just for fun, the demo in the repo writes to the page the file(s) that webpack created, as well as the files that are in the dist folder.

Caveats

The only negative side effect I can think of with this approach is that it might cause an extra Razor compilation — Basically, when the page first loads, I think it gets compiled first. But before the page fully loads, the ASP.NET UseWebpackDevMiddleware... code kicks in and runs webpack. Our webpack process, however, rewrites the very Razor file that we were trying to load in the first place. My hunch is that this causes the Razor file to be recompiled before being displayed. I’m not sure if any of that is correct, but it’s worth a consideration. If it’s true, the performance hit is minimal.

Am I crazy?

I hope that’s helpful to someone. Please let me know what you think!

Publishing a Visual Studio extension via command line

Microsoft not so recently added support for publishing Visual Studio extensions to the marketplace via a command line interface called vsixpublisher.

It’s no coincidence they tweeted me upon releasing the feature, as I’d been pestering them for a very long time to make it happen.

The walk-through I linked to will get you going, but might not get you all the way there. If you run into trouble trying to get it to work, here’s a reference implementation that might help:

I have an appveyor build that runs automatically, anytime someone pushes code to the master branch. Here’s how I configured the build to version, package, and publish the vsix to the marketplace.

https://github.com/alexdresko/HSPI/blob/master/update-vsixversion.ps1
This gets called as part of the “Before build script”. It sets the version number inside the vsix manifest based on the appveyor build number.
https://github.com/alexdresko/HSPI/blob/master/publish-vsix.ps1
This gets called as part of the “After deployment script” within my deployment. It’s the thing that actually pushes the built vsix to the marketplace. Note that I’ve configured my deployment to only fire when someone pushes to the master branch.

The trickiest part about the file is that it uses an environment variable to obtain the personal access token, since I don’t want to commit that to source control:

You can set the environment variable in appveyor here:

The MS article shows how to create the personal access token.
https://github.com/alexdresko/HSPI/blob/master/Templates/HomeSeerTemplates/publish-manifest.json
Standard file, almost completely copied from the MS documentation. Be careful to get the “internalName” right. I wish I knew more about how the internal name relates to the vsix identifier, as my lack of knowledge actually caused me to lose access to my plugin on the marketplace. Be careful…whatever that means.
https://github.com/alexdresko/HSPI/blob/master/Templates/HomeSeerTemplates/source.extension.vsixmanifest
This is just my vsix manifest for reference. You might even find it helpful to review the entire repo.

Last, but not least, the end result: https://marketplace.visualstudio.com/items?itemName=thealexdresko.HomeSeerTemplates2

I hope that helps someone who wants to get started using vsixpublisher. let me know if you have any questions, and I’ll try to help.

What is ASP.NET Core 2.1 API “Problem Details” (RFC 7807)

When ASP.NET Core 2.1 came out, there’s was a relatively brief announcement about new support for “Problem Details” (RFC 7807).

In this release we added support for RFC 7808 – Problem Details for HTTP APIs as a standardized format for returning machine readable error responses from HTTP APIs.

If you just want a better explanation of problem details, fear not. I read the documentation for you. …Continue reading “What is ASP.NET Core 2.1 API “Problem Details” (RFC 7807)” [What is ASP.NET Core 2.1 API “Problem Details” (RFC 7807)]

Chromebook life

Who would have thought I’d love a $500 Chromebook as much as I love my $4000 Dell M6800 (32GB RAM, 1.5TB SSD, I7)? I’ve been so productive over the past four days of ownership that I’m honestly pretty frustrated I didn’t fork over the money for this thing earlier. …Continue reading “Chromebook life” [Chromebook life]

Thoughts: The Stack Overflow 2017 Developer Survey Results

I found it useful this year to take some notes as I skimmed through the always interesting Stack Overflow developer survey results. Here’s what I came out with this year: …Continue reading “Thoughts: The Stack Overflow 2017 Developer Survey Results” [Thoughts: The Stack Overflow 2017 Developer Survey Results]

The difference between a junior and senior level software engineer?

I dislike titles. Keep reading to find out why. …Continue reading “The difference between a junior and senior level software engineer?” [The difference between a junior and senior level software engineer?]

What is your definition of a full-stack developer?

Funny you should ask – I’m known for having a strong distaste for the “full-stack developer” moniker, and I’ve started many a friendly debate on the subject. …Continue reading “What is your definition of a full-stack developer?” [What is your definition of a full-stack developer?]

How does an organization best achieve software quality?

Great question! But is quality even important? Is it possible? How do you know if you’ve achieved quality? …Continue reading “How does an organization best achieve software quality?” [How does an organization best achieve software quality?]

What is your definition of “done”?

Such a vital question in the software development world! “Doneness” is how you measure progress. And so it seems important that we should create some definition of the term. …Continue reading “What is your definition of “done”?” [What is your definition of “done”?]