refactor(migrate): Simplify engine API of evaluateDataLoss in Migrate (…

…#7576)

Co-authored-by: Jan Piotrowski <piotrowski+github@gmail.com>
Co-authored-by: Joël Galeran <Jolg42@users.noreply.github.com>

src/packages/migrate/README.md

@@ -24,7 +24,6 @@
 
 **Prisma Migrate** is an imperative database schema migration tool that enables you to make changes to your database schema. Migrations are auto-generated based on the Prisma schema changes but are fully customizable.
 
-> **WARNING**: Prisma Migrate is currently in an **preview**. There may be bugs and it's not recommended to use it in production environments.
 > Please help us improve Prisma Migrate by creating [issues](https://github.com/prisma/prisma/issues/new/choose) and sharing your [feedback](https://slack.prisma.io/) with us.
 
 ## Documentation

src/packages/migrate/src/commands/MigrateDev.ts

@@ -228,10 +228,7 @@ ${chalk.bold('Examples')}
     }
 
     let migrationName: undefined | string = undefined
-    if (
-      evaluateDataLossResult.migrationSteps.length > 0 ||
-      args['--create-only']
-    ) {
+    if (evaluateDataLossResult.migrationSteps > 0 || args['--create-only']) {
       const getMigrationNameResult = await getMigrationName(args['--name'])
 
       if (getMigrationNameResult.userCancelled) {

src/packages/migrate/src/types.ts

@@ -123,8 +123,8 @@ export namespace EngineResults {
     // Todo
   }
   export interface EvaluateDataLossOutput {
-    /// The migration steps that would be generated. If this is 0, we wouldn't generate a new migration, unless the `draft` option is passed.
-    migrationSteps: string[]
+    /// The number of migration steps that would be generated. If this is 0, we wouldn't generate a new migration, unless the `draft` option is passed.
+    migrationSteps: number
 
     /// The warnings and unexecutable migration messages that apply to the _development database_.
     /// The warnings for the production databases are written as comments into the migration scripts.