1 files changed, 50 insertions, 0 deletions
diff --git a/lib/Ultramarine/Model/DBMigration.pm6 b/lib/Ultramarine/Model/DBMigration.pm6
new file mode 100644
index 0000000..e2ac3b8
--- /dev/null
+++ b/lib/Ultramarine/Model/DBMigration.pm6
@@ -0,0 +1,50 @@
+use v6.d.PREVIEW;
+use DBI::Async;
+
+class Ultramarine::Model::DBMigration {
+    has $.dbh is required;
+    has Callable @.migrations = ();
+
+    method get-meta() {
+        return $.dbh.query(q:to/END/).hash;
+        SELECT *
+        FROM meta
+        ORDER BY version DESC
+        LIMIT 1
+        END
+        CATCH { when X::DBDish::DBError { return Nil } }
+    }
+
+    method !update-meta(*%new-values) {
+        my @columns = %new-values.keys;
+        my @values = %new-values{|@columns};
+        my $query = qq:to/END/;
+        INSERT INTO meta({@columns.join(',')})
+        VALUES ({@columns.map({'?'}).join(',')})
+        END
+        say $query;
+        $.dbh.query($query,@values).finish;
+    }
+
+    method !create-meta() {
+        $.dbh.query(q:to/END/).finish;
+        CREATE TABLE meta (
+            version INTEGER NOT NULL,
+            done_at TEXT DEFAULT (datetime('now'))
+        )
+        END
+        self!update-meta(:0version);
+        return %(:0version);
+    }
+
+    method ensure-schema() {
+        my %meta = self.get-meta() //
+            self!create-meta();
+        my $version = %meta<version>;
+        while (@.migrations[$version]) -> $migration {
+            $migration.($.dbh);
+            ++$version;
+            self!update-meta(:$version);
+        }
+    }
+}