Schema updates can be done manually or automatically as described here.
The **EPiServer.Net.Cli **cmd manually updates the the database scheme as described in [Install Optimizely](🔗). You can configure the site to automatically apply updates to the SQL schema during site initialization.
When the site starts, it compares the assembly version and the database version. If the database version is lower than the assembly version and automatic updates are enabled, it applies the SQL schema updates. (The SQL files are embedded resources in the assembly.) To enable automatic schema updates, add attribute updateDatabaseSchema="true" to the _appsetting.json_ configuration as shown below:
Or you can do it by code like this:
If you enable automatic schema updates, you can interact with the schema upgrade process by registering an implementation of ISchemaValidator**\*** in the IOC container. The interface has two methods:
IsDatabaseUpdateAllowed – The schema calls this method first where an implementation can check if an automatic update should be allowed.
BeforeUpdating – If all validators allow automatic schema update, the schema calls the method before it performs the actual update, so you can perform some action such a backup of the database.
Validators are also called if automatic schema creation as described in [Installing database schemas](🔗) has been enabled and a new schema is about to be deployed.
The following example shows a basic implementation that allows updates but takes a database backup:
The following example allows only automatic updates when running on LocalDB (typical development environment):
You can register several validators. For example, if both validators in the previous examples are registered, updates are allowed only when running on LocalDB and it makes a backup before the update is applied.