I'm using dotnet ef migrations add {MigrationName}
in order to create a new migration.
In case there are no Entities/Context changes this creates a migration with empty Up(MigrationBuilder migrationBuilder)
and Down(MigrationBuilder migrationBuilder)
functions.
Is there a way for the migrations add
command to skip the creation of 'empty' files?
Alternatively, Is there a way to detect if there are changes before running the migrations add
command?
I found a solution to this problem.
There is a way to create migrations programmatically instead of using CLI.
After looking at the MigrationsScaffolder source code I managed to modify the code in the first link in order to support my needs:
using (var db = new MyDbContext())
{
var reporter = new OperationReporter(
new OperationReportHandler(
m => Console.WriteLine(" error: " + m),
m => Console.WriteLine(" warn: " + m),
m => Console.WriteLine(" info: " + m),
m => Console.WriteLine("verbose: " + m)));
var designTimeServices = new ServiceCollection()
.AddSingleton(db.GetService<IHistoryRepository>())
.AddSingleton(db.GetService<IMigrationsIdGenerator>())
.AddSingleton(db.GetService<IMigrationsModelDiffer>())
.AddSingleton(db.GetService<IMigrationsAssembly>())
.AddSingleton(db.Model)
.AddSingleton(db.GetService<ICurrentDbContext>())
.AddSingleton(db.GetService<IDatabaseProvider>())
.AddSingleton<MigrationsCodeGeneratorDependencies>()
.AddSingleton<ICSharpHelper, CSharpHelper>()
.AddSingleton<CSharpMigrationOperationGeneratorDependencies>()
.AddSingleton<ICSharpMigrationOperationGenerator, CSharpMigrationOperationGenerator>()
.AddSingleton<CSharpSnapshotGeneratorDependencies>()
.AddSingleton<ICSharpSnapshotGenerator, CSharpSnapshotGenerator>()
.AddSingleton<CSharpMigrationsGeneratorDependencies>()
.AddSingleton<IMigrationsCodeGenerator, CSharpMigrationsGenerator>()
.AddSingleton<IOperationReporter>(reporter)
.AddSingleton<MigrationsScaffolderDependencies>()
.AddSingleton<ISnapshotModelProcessor, SnapshotModelProcessor>()
.AddSingleton<MigrationsScaffolder>()
.BuildServiceProvider();
var scaffolderDependencies = designTimeServices.GetRequiredService<MigrationsScaffolderDependencies>();
var modelSnapshot = scaffolderDependencies.MigrationsAssembly.ModelSnapshot;
var lastModel = scaffolderDependencies.SnapshotModelProcessor.Process(modelSnapshot?.Model);
var upOperations = scaffolderDependencies.MigrationsModelDiffer.GetDifferences(lastModel, scaffolderDependencies.Model);
var downOperations = upOperations.Any() ? scaffolderDependencies.MigrationsModelDiffer.GetDifferences(scaffolderDependencies.Model, lastModel) : new List<MigrationOperation>();
if (upOperations.Count() > 0 || downOperations.Count() > 0)
{
var scaffolder = designTimeServices.GetRequiredService<MigrationsScaffolder>();
var migration = scaffolder.ScaffoldMigration(
"MyMigration",
"MyApp.Data");
File.WriteAllText(
migration.MigrationId + migration.FileExtension,
migration.MigrationCode);
File.WriteAllText(
migration.MigrationId + ".Designer" + migration.FileExtension,
migration.MetadataCode);
File.WriteAllText(migration.SnapshotName + migration.FileExtension,
migration.SnapshotCode);
}
}