ASP.NET Core - Old Solution Structure Vs. New Solution Structure
Recently one of the readers, who was quite new to ASP.NET Core, asked this
question -
"I am following your instructions to create a working example based on your
article. After creating the project my solution explorer looks different than
your screen shots. Why is so? Am I missing something?"
Well. That's actually because of a simple setting. But it is always good to
know why things are happening in the way they are. So, in this short post I am
explaining why you see two different solution structures in Visual Studio 2015.
Solution Structure - ASP.NET MVC 5 Style
Let's create a new ASP.NET MVC 5 project using Visual Studio 2015.
Open Visual Studio 2015 and select File > New > Project. This will open a new
project dialog as shown below:

Observe this dialog carefully. Specifically note the following:
- Project name is Project1
- Solution name is Solution1
- Create directory for solution checkbox is checked
When you complete the project creation your Solution Explorer will resemble
this:

If you glance over the folder structure using Windows explorer, you will have
this:

Notice that under the Demos folder you have Solution1 folder because you
selected the "Create directory for solution" checkbox. Inside, you have Project1
folder that contains all the project specific files and folders.
Now, create a new project again but this time uncheck the "Create directory
for solution" checkbox.

This time Project2 folder (the folder containing project's files and folders)
gets created directly inside Demos folder. There is no separate folder for
solution since you unchecked the "Create directory for solution" checkbox.
Solution Structure - ASP.NET Core Style
So far so good. Now create a new ASP.NET Core project by checking the "Create
directory for solution" checkbox.

This time project name is Project3 and solution name is Solution3. This time
your solution explorer would look like this:

That's bit different! Observe the following differences:
- There are two top level folders - Solution Items and src.
- Solution Items contains global.json file.
- Src folder contains the project - Project3.
Now try adding another project to the same solution by right clicking on
Solution3 (this process remains the same as before). After adding the new
project your Solution Explorer will resemble this:

Thus all the projects belonging to a solution are located inside the Src
folder. The physical folder structure will look like this:

You may ask - Why this structure?
That's because this structure closely resembles the GitHub project layout.
Since ASP.NET Core heavily uses OSS, the new solution structure mimics what
people using repositories such as GitHub are familiar with.
You are not limited to these two folders. You can, for example, create Tests
folder to store unit testing related things and Documentation folder to store
documentation files.
Now you may ask - Can I continue using the older solution structure in
ASP.NET Core also?
Yes. You can do that. Simply uncheck the "Create directory for solution"
checkbox while creating a project and you will have a solution with older and
familiar structure. Here is an example:

And the result is as follows:

That's it for now! Keep coding !!