![]() ![]() Two Ways to Implement a Composite KeyĪs an example, we will use the “PetClinic” application. Another example is that having a composite primary key in the many-to-many association table is a natural thing.īased on the above, we can conclude that we should learn how to deal with composite keys in our JPA entities. It can save us one “join” when we search all cities for a particular country. And then create a composite primary key for the “cities” table that will include country ID and region ID. We can make a country ID a part of a region’s primary key. This approach is practical when we either build an application over an existing “legacy” database or use carefully and thoroughly optimized database schema usually developed by a DBA.įor example, we can create tables to store countries, regions, and cities. So, composite keys are not that rare, especially when using the “database-first” development approach. ![]() Recently there was a poll on Twitter, and results showed that about 55% of developers would use composite keys if required: It might seem that composite keys are not needed in modern applications, but it is not like this. Now it is time to discuss less popular but still useful ID type – composite ID. I recently browsed the Microsoft Docs after (again) losing time chasing configuration issues when I came across IValidateOptions.Previously, we talked about IDs generated in database and applications, discussed the pros and cons of various strategies for generation and implementation details. That is, settings are present but not valid in the context of the application. The second variant is the most likely to occur. Take the following JSON configuration: '", nameof(key))Ĭaution: configurationIsRoot.GetDebugView() prints all configuration settings and their value, if you have secrets you should add log masking to prevent them from being logged. Via means of ChainedConfiguration the entire HostConfiguration is also available as part of AppConfiguration. The HostConfiguration is used to set variables like the DOTNET_ENVIRONMENT, which is used to load the proper appsettings.json and user secrets. You have the AppConfiguration we just discussed, and you have the HostConfiguration. Fun fact, there are two configurations in ASP.NET. Passing a setting via the command line will always win from a setting in the appsettings.json file. The priority of settings is in the reverse order of adding them to the builder. user secrets (if the environment is development).This default builder also takes care of the default configuration. You get a default HostBuilder that setups an IHost. In fact, you get a preconfigured configuration builder every time you use the ASP.NET Web templates. In reality, you use an IConfigurationBuilder where different providers are provided, and the configuration block in the middle is the merged build-result of the configuration builder. Technically the image above is an over-simplification. I've attempted to illustrate it with the image below. In contrast, the options concept provides access to configuration from our application code. NET is the combination of different configuration sources, called configuration providers, resulting in a single combined configuration. ![]() An IOptions is used to make a configuration available as a strongly typed type in our applications.Īs I understand it, the configuration concept in. NET, we use the IConfigurationBuilder to manage our configuration. Chapter three of "The Twelve-Factor App" explains why separating configuration from code is a good idea. Almost every project will have some settings that are configured differently per environment. ![]()
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