Can I use ListMigrations to show a list of Migrations on an MVC Page?

[asifshakir]

Hello,

Can I use ListMigrations to show a list of available migrations to the user on an ASP.NET Core MVC Website (using .NET Core 5.0)?

        var serviceProvider = CreateServices();
        using (var scope = serviceProvider.CreateScope())
        {
            var runner = serviceProvider.GetRequiredService<IMigrationRunner>();
            runner.ListMigrations();
        }

I believe I would need some way to fetch the output of ListMigrations and show pass it to the view.

[jzabroski]

@asifshakir MigrationRunner has a public constructor that takes an ILogger instance:

fluentmigrator/src/FluentMigrator.Runner/MigrationRunner.cs

Line 202 in 7033cdf

[NotNull] ILogger<MigrationRunner> logger,

I could envision a "logger" component that has a public property which is the data structure for your ASP.NET MVC view.

However, a cleaner solution would probably be to modularize MigrationRunner. I would start with just what you need modularized, e.g.,

fluentmigrator/src/FluentMigrator.Runner/MigrationRunner.cs

Lines 912 to 937 in 7033cdf

	public void ListMigrations()
	{
	var currentVersionInfo = VersionLoader.VersionInfo;
	var currentVersion = currentVersionInfo.Latest();
	_logger.LogHeader("Migrations");
	foreach (var migration in MigrationLoader.LoadMigrations())
	{
	var migrationName = migration.Value.GetName();
	var status = GetStatus(migration, currentVersion);
	var statusString = string.Join(", ", GetStatusStrings(status));
	var message = $"{migrationName}{(string.IsNullOrEmpty(statusString) ? string.Empty : $" ({statusString})")}";
	var isCurrent = (status & MigrationStatus.AppliedMask) == MigrationStatus.Current;
	var isBreaking = (status & MigrationStatus.Breaking) == MigrationStatus.Breaking;
	if (isCurrent || isBreaking)
	{
	_logger.LogEmphasized(message);
	}
	else
	{
	_logger.LogSay(message);
	}
	}
	}

Something like the following should be a self-contained Service:

// Assume MigrationWithStatus is a DTO.
// Therefore, MigrationWithStatus  does not contain any methods or transitive references to objects that contain methods.
public ICollection<MigrationWithStatus> GetMigrationsWithStatus()
{
            var currentVersionInfo = VersionLoader.VersionInfo;
            var currentVersion = currentVersionInfo.Latest();

            var migrationsWithStatus = MigrationLoader
                        .LoadMigrations()
                        .Select(migration => {
                                    var migrationName = migration.Value.GetName();
                                    var status = GetStatus(migration , currentVersion);
                                    var statusStrings = GetStatusStrings(status);
                                    var statusString = string.Join(",", statusStrings);
                                    return
                                                new MigrationWithStatus() {
                                                            Name = migrationName,
                                                            Status = status,
                                                            StatusDetails = GetStatusStrings(status),
                                                            IsCurrent = (status & MigrationStatus.AppliedMask) == MigrationStatus.Current,
                                                            IsBreaking = (status & MigrationStatus.Breaking) == MigrationStatus.Breaking,
                                                            Message = $"{migrationName}{(string.IsNullOrEmpty(statusString) ? string.Empty : $" ({statusString})")}",
                                                };
                        })
                        .ToList();
            return migrationsWithStatus;
}

You would need to basically take my proof-of-concept above and,

1. Flesh out MigrationWIthStatus DTO - I recommend adding a get-only property that applies ViewModel logic such as public bool IsEmphasized => IsCurrent || IsBreaking;
2. Create a Service
3. Construct the Service inside the existing MigrationRunner constructor, for now, so that it is not a public breaking API change
4. Update the MigrationRunner.ListMigrations method to use the Service and write the appropriate Log messages
5. You can then add to the DI namespace a helper for also creating an IMyNewService - open to suggestions on what to call this.
6. Write tests for the above so that we have code coverage.