Add new command: create to add new migrations (#815)

This PR adds a new command named `create`. It lets users create new
migration files. It has three flags: `--empty` if the user wants to
create an empty file and `--name` if the user wants to pass a name
instead of being prompted. Similarly to `pull` command it also has a
flag called `--json` to output the migration file in json format.

I am adding documentation in a follow-up PR.

Author: kvch

cli-definition.json

@@ -37,6 +37,34 @@
         "migration-file"
       ]
     },
+    {
+      "name": "create",
+      "short": "Create a new migration interactively",
+      "use": "create",
+      "example": "",
+      "flags": [
+        {
+          "name": "empty",
+          "shorthand": "e",
+          "description": "Create empty migration file",
+          "default": "false"
+        },
+        {
+          "name": "json",
+          "shorthand": "j",
+          "description": "Output migration file in JSON format instead of YAML",
+          "default": "false"
+        },
+        {
+          "name": "name",
+          "shorthand": "n",
+          "description": "Migration name",
+          "default": ""
+        }
+      ],
+      "subcommands": [],
+      "args": []
+    },
     {
       "name": "init",
       "short": "Initialize pgroll in the target database",

cmd/create.go

@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: Apache-2.0
+
+//nolint:goconst
+package cmd
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"github.com/pterm/pterm"
+	"github.com/spf13/cobra"
+	"github.com/xataio/pgroll/pkg/migrations"
+	"sigs.k8s.io/yaml"
+)
+
+func createCmd() *cobra.Command {
+	var isEmpty bool
+	var useJSON bool
+	var name string
+
+	createCmd := &cobra.Command{
+		Use:   "create",
+		Short: "Create a new migration interactively",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			if name == "" {
+				name, _ = pterm.DefaultInteractiveTextInput.
+					WithDefaultText("Set the name of your migration").
+					Show()
+			}
+
+			mig := &migrations.Migration{}
+			addMoreOperations := !isEmpty
+
+			for addMoreOperations {
+				selectedOption, _ := pterm.DefaultInteractiveSelect.
+					WithDefaultText("Select operation").
+					WithOptions(migrations.AllNonDeprecatedOperations).
+					Show()
+
+				op, _ := migrations.OperationFromName(migrations.OpName(selectedOption))
+				mig.Operations = append(mig.Operations, op)
+				if operation, ok := op.(migrations.Createable); ok {
+					operation.Create()
+				}
+				addMoreOperations, _ = pterm.DefaultInteractiveConfirm.
+					WithDefaultText("Add more operations").
+					Show()
+			}
+
+			outputFormat := "yaml"
+			if useJSON {
+				outputFormat = "json"
+			}
+			migrationFileName := fmt.Sprintf("%s.%s", name, outputFormat)
+			file, err := os.Create(migrationFileName)
+			if err != nil {
+				return fmt.Errorf("failed to create migration file: %w", err)
+			}
+			defer file.Close()
+
+			switch outputFormat {
+			case "json":
+				enc := json.NewEncoder(file)
+				enc.SetIndent("", "  ")
+				if err := enc.Encode(mig); err != nil {
+					return fmt.Errorf("failed to encode migration: %w", err)
+				}
+			case "yaml":
+				out, err := yaml.Marshal(mig)
+				if err != nil {
+					return fmt.Errorf("failed to encode migration: %w", err)
+				}
+				_, err = file.Write(out)
+				if err != nil {
+					return fmt.Errorf("failed to write migration: %w", err)
+				}
+			default:
+				return fmt.Errorf("invalid output format: %q", outputFormat)
+			}
+
+			pterm.Success.Println("Migration written to " + migrationFileName)
+
+			return nil
+		},
+	}
+	createCmd.Flags().BoolVarP(&isEmpty, "empty", "e", false, "Create empty migration file")
+	createCmd.Flags().BoolVarP(&useJSON, "json", "j", false, "Output migration file in JSON format instead of YAML")
+	createCmd.Flags().StringVarP(&name, "name", "n", "", "Migration name")
+
+	return createCmd
+}

cmd/root.go

@@ -101,6 +101,7 @@ func Prepare() *cobra.Command {
 	rootCmd.AddCommand(analyzeCmd)
 	rootCmd.AddCommand(initCmd)
 	rootCmd.AddCommand(statusCmd)
+	rootCmd.AddCommand(createCmd())
 	rootCmd.AddCommand(migrateCmd())
 	rootCmd.AddCommand(pullCmd())
 	rootCmd.AddCommand(latestCmd())

pkg/migrations/migrations.go

@@ -34,6 +34,22 @@ type Operation interface {
 	Validate(ctx context.Context, s *schema.Schema) error
 }
 
+// Createable interface must be implemented for all operations
+// that can be created using the CLI create command.
+//
+// The function must prompt users to configure all attributes of an operation.
+//
+// Example implementation for OpMyOperation that has 3 attributes: table, column and down:
+//
+//	func (o *OpMyOperation) Create() {
+//		o.Table, _ = pterm.DefaultInteractiveTextInput.WithDefaultText("table").Show()
+//		o.Column, _ = pterm.DefaultInteractiveTextInput.WithDefaultText("column").Show()
+//		o.Down, _ = pterm.DefaultInteractiveTextInput.WithDefaultText("down").Show()
+//	}
+type Createable interface {
+	Create()
+}
+
 // IsolatedOperation is an operation that cannot be executed with other operations
 // in the same migration.
 type IsolatedOperation interface {

pkg/migrations/migrations_test.go

@@ -103,3 +103,14 @@ func TestCollectFilesFromDir(t *testing.T) {
 		})
 	}
 }
+
+func TestAllNonDeprecatedOperationsAreCreateable(t *testing.T) {
+	for _, opName := range migrations.AllNonDeprecatedOperations {
+		t.Run(opName, func(t *testing.T) {
+			op, err := migrations.OperationFromName(migrations.OpName(opName))
+			assert.NoError(t, err)
+			_, ok := op.(migrations.Createable)
+			assert.True(t, ok, "operation %q must have a Create function", opName)
+		})
+	}
+}

pkg/migrations/op_add_column.go

@@ -16,7 +16,10 @@ import (
 	"github.com/xataio/pgroll/pkg/schema"
 )
 
-var _ Operation = (*OpAddColumn)(nil)
+var (
+	_ Operation  = (*OpAddColumn)(nil)
+	_ Createable = (*OpAddColumn)(nil)
+)
 
 func (o *OpAddColumn) Start(ctx context.Context, l Logger, conn db.DB, latestSchema string, s *schema.Schema) (*schema.Table, error) {
 	l.LogOperationStart(o)

pkg/migrations/op_alter_column.go

@@ -13,7 +13,10 @@ import (
 	"github.com/xataio/pgroll/pkg/schema"
 )
 
-var _ Operation = (*OpAlterColumn)(nil)
+var (
+	_ Operation  = (*OpAlterColumn)(nil)
+	_ Createable = (*OpAlterColumn)(nil)
+)
 
 func (o *OpAlterColumn) Start(ctx context.Context, l Logger, conn db.DB, latestSchema string, s *schema.Schema) (*schema.Table, error) {
 	l.LogOperationStart(o)

pkg/migrations/op_common.go

@@ -36,6 +36,25 @@ const (
 	OpCreateConstraintName          OpName = "create_constraint"
 )
 
+// AllNonDeprecatedOperations contains the list of operations
+// that are not deprecated. These operations must implement
+// migrations.Createable interface.
+var AllNonDeprecatedOperations = []string{
+	string(OpNameCreateTable),
+	string(OpNameRenameTable),
+	string(OpNameRenameColumn),
+	string(OpNameDropTable),
+	string(OpNameAddColumn),
+	string(OpNameDropColumn),
+	string(OpNameAlterColumn),
+	string(OpNameCreateIndex),
+	string(OpNameDropIndex),
+	string(OpNameRenameConstraint),
+	string(OpNameDropMultiColumnConstraint),
+	string(OpRawSQLName),
+	string(OpCreateConstraintName),
+}
+
 const (
 	temporaryPrefix = "_pgroll_new_"
 	deletedPrefix   = "_pgroll_del_"
@@ -155,7 +174,7 @@ func (v *Operations) UnmarshalJSON(data []byte) error {
 			logBody = v
 		}
 
-		item, err := operationFromName(opName)
+		item, err := OperationFromName(opName)
 		if err != nil {
 			return err
 		}
@@ -253,7 +272,7 @@ func OperationName(op Operation) OpName {
 	panic(fmt.Errorf("unknown operation for %T", op))
 }
 
-func operationFromName(name OpName) (Operation, error) {
+func OperationFromName(name OpName) (Operation, error) {
 	switch name {
 	case OpNameCreateTable:
 		return &OpCreateTable{}, nil

pkg/migrations/op_create_constraint.go

@@ -13,7 +13,10 @@ import (
 	"github.com/xataio/pgroll/pkg/schema"
 )
 
-var _ Operation = (*OpCreateConstraint)(nil)
+var (
+	_ Operation  = (*OpCreateConstraint)(nil)
+	_ Createable = (*OpCreateConstraint)(nil)
+)
 
 func (o *OpCreateConstraint) Start(ctx context.Context, l Logger, conn db.DB, latestSchema string, s *schema.Schema) (*schema.Table, error) {
 	l.LogOperationStart(o)

pkg/migrations/op_create_index.go

@@ -13,7 +13,10 @@ import (
 	"github.com/xataio/pgroll/pkg/schema"
 )
 
-var _ Operation = (*OpCreateIndex)(nil)
+var (
+	_ Operation  = (*OpCreateIndex)(nil)
+	_ Createable = (*OpCreateIndex)(nil)
+)
 
 func (o *OpCreateIndex) Start(ctx context.Context, l Logger, conn db.DB, latestSchema string, s *schema.Schema) (*schema.Table, error) {
 	l.LogOperationStart(o)