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Entity Framework Migrations

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Excluding Test Data in Production

5:54 with James Churchill

Let's see how we can update our Configuration class to exclude our test data when we're not building a debug version of our application.

It's not unusual for the needs and requirements for sea dated to be different 0:00
between the various environments that you need to support. 0:04
For instance a mike look at data, test data, 0:07
is often only needed in local developer and test environments. 0:10
And once you're ready to release a version of your application into production, 0:15
you'll want to exclude it. 0:19
Up until now, we've been using the debug built configuration by default 0:21
Visual Studio projects also include a release configuration. 0:26
As the name suggest, the debug configuration is used for 0:30
debugging your application. 0:34
While the release configuration is used to build a version of your application 0:36
that's optimized for release into your production environment. 0:40
It's also possible to create custom build configurations. 0:44
For example, you could create a test build configuration to use 0:48
when building your application for your test environment. 0:52
See the teachers notes for 0:55
more information on how to create custom build configurations. 0:56
Preprocessor directives can be used to conditionally include or 1:00
exclude code based on build configurations. 1:05
Preprocessor directives are instructions for 1:08
the compiler to preprocess before it compiles your code. 1:11
Lets see how we could update our configuration class to exclude our test 1:15
data when we're not building a debug version of our application. 1:19
To do that, we can wrap our test data in an if, preprocessor directive. 1:23
In order to only include that code in the compilation 1:28
of our application when the debug symbol is defined. 1:31
I'm going to consider everything other than the row look up data to be test data. 1:36
So, a place to preprocessor directive on a new line before our artist ID Constance. 1:41
Preprocessor directives start with a pound sign, 1:47
followed by the name of the directive. 1:50
Then, we type the name of the symbol that we want to check for. 1:53
You can think of preprocessor symbols as variables that can be used 1:58
with preprocessor directives. 2:02
The DEBUG symbol is defined by the DEBUG build configuration but 2:05
not by the release build configuration. 2:10
So that's a good symbol for 2:12
us to use in order to determine which build configuration is selected. 2:13
Symbols or case sensitive and then DEBUG symbol is defined using uppercase letters. 2:18
So it's important to type debug in all uppercase letters and not Debug or debug. 2:24
Otherwise the #if directive won't ever evaluate to true. 2:32
Preprocessor directives aren't code statements. 2:41
So they don't end with a semicolon. 2:43
Now let's scroll down to the bottom of our test data and add the endif directive. 2:46
#endif Visual Studio will 2:57
give us a subtle visual indication when code isn't being included in compilation. 3:07
If we switch to the release build configuration, we can see that the editor 3:13
will dim the color of the code in between our preprocessor directives to gray. 3:16
If we switch back to debug build configuration, 3:22
we can see that the default syntax color highlighting returns, 3:25
indicating that the code will be included in the compilation of our application. 3:29
Let's test our changes. 3:33
Switch to the release build configuration. 3:35
Delete or drop our database 3:40
Run the update database command. 3:52
Update- database. 3:58
And then, run the application without debugging by pressing Ctrl+F5. 4:04
And now, we're not getting any comic books returned from 4:08
our query press Enter twice to continue execution. 4:13
Let's double check that the comic book table doesn't contain any data. 4:20
And the table doesn't contain any rows just as we expected. 4:34
If we switch to the debug build configuration Run 4:41
the update database command, 4:45
And press F5 to run our application, 4:56
we'll see our list of comic books from our test data. 4:59
We're just scratching the surface of what's possible with build configurations 5:05
and preprocessor directives. 5:09
See the teacher's notes for information on both. 5:11
Let's do a quick review of the section. 5:14
We saw how to enable migrations for 5:17
our project using the Enable migrations command. 5:19
And our initial migration using the add migration command, and 5:22
update our database using the update database command. 5:27
We also saw how to use the Code First migrations 5:30
configuration class to seed our database with look up and test dat. 5:34
In the next section, we'll dig deeper into Code First migrations Well, 5:37
out of migration for a simple model change. 5:43
Look at an example of how to modify a migration, 5:45
see how to downgrade our database and review our deployment options. 5:48
See you after the break. 5:53