Added UP command (not working).

db_migrate.nim

@@ -3,9 +3,19 @@
 ##
 ## Simple tool to manage database migrations.
 
-import json, times, os, strutils, docopt, db_postgres, db_mysql, db_sqlite
+import algorithm, json, times, os, strutils, docopt, db_postgres, sets,
+  sequtils
 
-type DbMigrateConfig* = tuple[ driver, sqlDir, connectionString: string ]
+type 
+  LogLevel = enum quiet, normal, verbose, very_verbose
+  DbMigrateConfig* = tuple[ driver, sqlDir, connectionString: string, logLevel: LogLevel ]
+
+proc createMigrationsTable(conn: DbConn): void =
+  conn.exec(sql("""
+CREATE TABLE IF NOT EXISTS migrations (
+  id SERIAL PRIMARY KEY,
+  name VARCHAR NOT NULL,
+  run_at TIMESTAMP NOT NULL DEFAULT NOW())"""))
 
 proc loadConfig*(filename: string): DbMigrateConfig =
   ## Load DbMigrateConfig from a file. 
@@ -14,14 +24,8 @@ proc loadConfig*(filename: string): DbMigrateConfig =
   return (
     driver: if cfg.hasKey("driver"): cfg["driver"].getStr else: "postres",
     sqlDir: if cfg.hasKey("sqlDir"): cfg["sqlDir"].getStr else: "migrations",
-    connectionString: cfg["connectionString"].getStr)
-
-proc getDbConnection*(config: DbMigrateConfig): DbConn =
-  case config.driver
-  of "postgres": discard
-  of "sqlite": discard
-  of "mysql": discard
-  else: dbError "Unsupported database driver: " & config.driver
+    connectionString: cfg["connectionString"].getStr,
+    logLevel: if cfg.hasKey("logLevel"): parseEnum[LogLevel](cfg["logLevel"].getStr) else: normal)
 
 proc createMigration*(config: DbMigrateConfig, migrationName: string): seq[string] =
   ## Create a new set of database migration files.
@@ -44,17 +48,100 @@ proc createMigration*(config: DbMigrateConfig, migrationName: string): seq[strin
 
   return @[upFilename, downFilename]
 
+proc diffMigrations*(pgConn: DbConn, config: DbMigrateConfig):
+  tuple[ run, notRun, missing: seq[string] ] =
+
+  # Query the database to find out what migrations have been run.
+  var migrationsRun = initSet[string]()
+
+  for row in pgConn.fastRows(sql"SELECT * FROM migrations ORDER BY name", @[]):
+    migrationsRun.incl(row[1])
+ 
+  # Inspect the filesystem to see what migrations are available.
+  var migrationsAvailable = initSet[string]()
+  for filePath in walkFiles(joinPath(config.sqlDir, "*.sql")):
+    var migrationName = filePath.extractFilename
+    migrationName.removeSuffix("-up.sql")
+    migrationName.removeSuffix("-down.sql")
+    migrationsAvailable.incl(migrationName)
+
+  # Diff with the list of migrations that we have in our migrations
+  # directory.
+  let migrationsInOrder =
+    toSeq(migrationsAvailable.items).sorted(system.cmp)
+
+  var migrationsNotRun: seq[string] = @[]
+  var missingMigrations: seq[string] = @[]
+
+  for migration in migrationsInOrder:
+    if not migrationsRun.contains(migration):
+      migrationsNotRun.add(migration)
+
+    # if we've already seen some migrations that have not been run, but this
+    # one has been, that means we have a gap and are missing migrations
+    elif migrationsNotRun.len > 0:
+      missingMigrations.add(migrationsNotRun)
+      migrationsNotRun = @[]
+ 
+  return (run: toSeq(migrationsRun.items), notRun: migrationsNotRun, missing: missingMigrations)
+
+proc up*(config: DbMigrateConfig, count: int): seq[string] =
+  let pgConn = open("", "", "", config.connectionString)
+  pgConn.createMigrationsTable
+
+  let (run, toRun, missing) = diffMigrations(pgConn, config)
+ 
+  # Make sure we have no gaps (database is in an unknown state)
+  if missing.len > 0:
+    dbError("Database is in an inconsistent state. Migrations have been " &
+      "run that are not sequential.")
+
+  var migrationsRun: seq[string] = @[]
+  if toRun.len > 0:
+    # Begin a transaction.
+    pgConn.exec(sql"BEGIN")
+
+    let rollbackWithErr = proc (errMsg: string): void =
+      pgConn.exec(sql"ROLLBACK")
+      dbError(errMsg)
+
+    # Apply each of the migrations.
+    for migration in toRun:
+      let filename = joinPath(config.sqlDir, migration & "-up.sql")
+
+      if not filename.fileExists:
+        rollbackWithErr "Can not find up file for " & migration &
+          ". Expected '" & filename & "'."
+
+      let migrationSql = filename.readFile
+      try:
+        pgConn.exec(sql(migrationSql))
+        migrationsRun.add(migration)
+      except DbError:
+        rollbackWithErr "Migration '" & migration & "'failed:\n\t" &
+          getCurrentExceptionMsg()
+
+
+  return migrationsRun
+    
 when isMainModule:
   let doc = """
 Usage:
-  db-migrate [options] create <migration-name>
-  db-migrate [options] up [<count>]
-  db-migrate [options] down [<count>]
-  db-migrate [options] init <schema-name>
+  db_migrate [options] create <migration-name>
+  db_migrate [options] up [<count>]
+  db_migrate [options] down [<count>]
+  db_migrate [options] init <schema-name>
+  db_migrate (-V | --version)
 
 Options:
+
   -c --config <config-file>   Use the given configuration file (defaults to 
                               "database.json").
+
+  -v --verbose                Print detailed log information (use -vv to
+                              print even more details).
+
+  -V --version                Print the tools version information.
 """
 
   # Parse arguments
@@ -66,7 +153,7 @@ Options:
 
   # Load configuration file
   let configFilename =
-    if args["--config"]: $args["--config"]
+    if args["--config"]: $args["<config-file>"]
     else: "database.json"
 
   var config: DbMigrateConfig
@@ -95,24 +182,14 @@ Options:
     except IOError:
       exitErr "Unable to create migration scripts: " & getCurrentExceptionMsg()
 
-  elif args["up"]: discard
-    # Query the database to find out what migrations have been run.
-
-    # Diff with the list of migrations that we have in our migrations
-    # directory.
-
-    # Make sure we have no gaps (database is in an unknown state)
-
-    # Find the subset of migrations we need to apply (consider the count
-    # parameter if passed)
-
-    # If none: "Up to date."
-
-    # Begin a transaction.
-
-      # Apply each of the migrations.
-      # If any fail, roll back the transaction
-      # Otherwise report success
+  elif args["up"]:
+    try:
+      let migrationsRun = up(config, if args["<count>"]: parseInt($args["<count>"]) else: 1)
+      for migration in migrationsRun:
+        echo migration
+      echo "Up to date."
+    except DbError:
+      exitErr "Unable to migrate database: " & getCurrentExceptionMsg()
 
   elif args["down"]: discard
     # Query the database to find out what migrations have been run.