Abort generation if file exists and matches glob (#91)

* Abort generation if file exists and matches glob

resolves #90

With this, a user can have Gnorm generate a file once and prevent
further generation (thus preserving future edits). Or prevent
accidental overwrites of files during generation. There are, I'm sure,
other use cases I can't envision at this time.

* Log when skipping file

* Remove extraneous NoOverwriteGlobs

cli/config.go

@@ -124,4 +124,9 @@ type Config struct {
 	// The directory structure is preserved when copying the files to the
 	// OutputDir
 	StaticDir string
+
+	// NoOverwriteGlobs is a list of globs
+	// (https://golang.org/pkg/path/filepath/#Match). If a filename matches a glob
+	// *and* a file exists with that name, it will not be generated.
+	NoOverwriteGlobs []string
 }

cli/gnorm.toml

@@ -7,7 +7,7 @@
 ConnStr = "dbname=mydb host=127.0.0.1 sslmode=disable user=admin"
 
 # DBType holds the type of db you're connecting to.  Possible values are
-# "postgres" or "mysql". 
+# "postgres" or "mysql".
 DBType = "postgres"
 
 # Schemas holds the names of schemas to generate code for.
@@ -63,6 +63,10 @@ OutputDir = "gnorm"
 # OutputDir
 StaticDir = "static"
 
+# NoOverwriteGlobs is a list of globs
+# (https://golang.org/pkg/path/filepath/#Match). If a filename matches a glob
+# *and* a file exists with that name, it will not be generated.
+NoOverwriteGlobs = ["*.perm.go"]
 
 # TablePaths is a map of output paths to template paths that tells Gnorm how to
 # render and output its table info and where to save that output.  Each template
@@ -146,4 +150,4 @@ StaticDir = "static"
 # different situations.  The values in this field will be available in the
 # .Params value for all templates.
 [Params]
-mySpecialValue = "some value"
+mySpecialValue = "some value"

cli/parse.go

@@ -66,17 +66,18 @@ func parse(env environ.Values, r io.Reader) (*run.Config, error) {
 
 	cfg := &run.Config{
 		ConfigData: data.ConfigData{
-			ConnStr:         c.ConnStr,
-			DBType:          c.DBType,
-			Schemas:         c.Schemas,
-			NullableTypeMap: c.NullableTypeMap,
-			TypeMap:         c.TypeMap,
-			PostRun:         c.PostRun,
-			ExcludeTables:   exclude,
-			IncludeTables:   include,
-			OutputDir:       c.OutputDir,
-			StaticDir:       c.StaticDir,
-			PluginDirs:      c.PluginDirs,
+			ConnStr:          c.ConnStr,
+			DBType:           c.DBType,
+			Schemas:          c.Schemas,
+			NullableTypeMap:  c.NullableTypeMap,
+			TypeMap:          c.TypeMap,
+			PostRun:          c.PostRun,
+			ExcludeTables:    exclude,
+			IncludeTables:    include,
+			OutputDir:        c.OutputDir,
+			StaticDir:        c.StaticDir,
+			PluginDirs:       c.PluginDirs,
+			NoOverwriteGlobs: c.NoOverwriteGlobs,
 		},
 		Params: c.Params,
 	}

cli/parse_test.go

@@ -88,9 +88,10 @@ func TestParseConfig(t *testing.T) {
 			"integer":           "sql.NullInt64",
 			"numeric":           "sql.NullFloat64",
 		},
-		PluginDirs: []string{"plugins"},
-		OutputDir:  "gnorm",
-		StaticDir:  "static",
+		PluginDirs:       []string{"plugins"},
+		OutputDir:        "gnorm",
+		StaticDir:        "static",
+		NoOverwriteGlobs: []string{"*.perm.go"},
 	}
 	if diff := cmp.Diff(cfg.ConfigData, expected); diff != "" {
 		t.Fatalf("Actual differs from expected:\n%s", diff)

cli/sample.go

@@ -33,7 +33,7 @@ const sample = `# ConnStr is the connection string for the database.  Any enviro
 ConnStr = "dbname=mydb host=127.0.0.1 sslmode=disable user=admin"
 
 # DBType holds the type of db you're connecting to.  Possible values are
-# "postgres" or "mysql". 
+# "postgres" or "mysql".
 DBType = "postgres"
 
 # Schemas holds the names of schemas to generate code for.
@@ -89,6 +89,10 @@ OutputDir = "gnorm"
 # OutputDir
 StaticDir = "static"
 
+# NoOverwriteGlobs is a list of globs
+# (https://golang.org/pkg/path/filepath/#Match). If a filename matches a glob
+# *and* a file exists with that name, it will not be generated.
+NoOverwriteGlobs = ["*.perm.go"]
 
 # TablePaths is a map of output paths to template paths that tells Gnorm how to
 # render and output its table info and where to save that output.  Each template
@@ -172,5 +176,6 @@ StaticDir = "static"
 # different situations.  The values in this field will be available in the
 # .Params value for all templates.
 [Params]
-mySpecialValue = "some value"`
+mySpecialValue = "some value"
+`
 // [[[end]]]

run/data/data.go

@@ -215,6 +215,11 @@ type ConfigData struct {
 	// The directory structure is preserved when copying the files to the
 	// OutputDir
 	StaticDir string
+
+	// NoOverwriteGlobs is a list of globs
+	// (https://golang.org/pkg/path/filepath/#Match). If a filename matches a glob
+	// *and* a file exists with that name, it will not be generated.
+	NoOverwriteGlobs []string
 }
 
 // Strings is a named type of []string to allow us to put methods on it.

run/generate.go

@@ -63,7 +63,7 @@ func generateSchemas(env environ.Values, cfg *Config, db *data.DBData) error {
 		}
 		for _, target := range cfg.SchemaPaths {
 			env.Log.Printf("Generating output for schema %v", schema.Name)
-			if err := genFile(env, fileData, contents, target, cfg.PostRun, cfg.OutputDir); err != nil {
+			if err := genFile(env, fileData, contents, target, cfg.NoOverwriteGlobs, cfg.PostRun, cfg.OutputDir); err != nil {
 				return errors.WithMessage(err, "generating file for schema "+schema.Name)
 			}
 		}
@@ -82,7 +82,7 @@ func generateEnums(env environ.Values, cfg *Config, db *data.DBData) error {
 				Params: cfg.Params,
 			}
 			for _, target := range cfg.EnumPaths {
-				if err := genFile(env, fileData, contents, target, cfg.PostRun, cfg.OutputDir); err != nil {
+				if err := genFile(env, fileData, contents, target, cfg.NoOverwriteGlobs, cfg.PostRun, cfg.OutputDir); err != nil {
 					env.Log.Printf("Generating output for enum %v", enum.Name)
 					return errors.WithMessage(err, "generating file for enum "+enum.Name)
 				}
@@ -103,7 +103,7 @@ func generateTables(env environ.Values, cfg *Config, db *data.DBData) error {
 			}
 			fileData := struct{ Schema, Table string }{Schema: schema.Name, Table: table.Name}
 			for _, target := range cfg.TablePaths {
-				if err := genFile(env, fileData, contents, target, cfg.PostRun, cfg.OutputDir); err != nil {
+				if err := genFile(env, fileData, contents, target, cfg.NoOverwriteGlobs, cfg.PostRun, cfg.OutputDir); err != nil {
 					env.Log.Printf("Generating output for table %v", table.Name)
 					return errors.WithMessage(err, "generating file for table "+table.Name)
 				}
@@ -113,14 +113,28 @@ func generateTables(env environ.Values, cfg *Config, db *data.DBData) error {
 	return nil
 }
 
-func genFile(env environ.Values, filedata, contents interface{}, target OutputTarget, postrun []string, outputDir string) error {
+func genFile(env environ.Values, filedata, contents interface{}, target OutputTarget, noOverwriteGlobs, postrun []string, outputDir string) error {
 	buf := &bytes.Buffer{}
 	err := target.Filename.Execute(buf, filedata)
 	if err != nil {
 		return errors.WithMessage(err, "failed to run Filename template")
 	}
 	outputPath := filepath.Join(outputDir, buf.String())
 
+	// if file exists and filename matches glob, abort
+	if _, err := os.Stat(outputPath); err == nil {
+		for _, glob := range noOverwriteGlobs {
+			m, err := filepath.Match(glob, buf.String())
+			if err != nil {
+				return errors.WithMessage(err, "error checking glob")
+			}
+			if m {
+				env.Log.Printf("Skipping generation for file %s", buf.String())
+				return nil
+			}
+		}
+	}
+
 	if err := os.MkdirAll(filepath.Dir(outputPath), 0700); err != nil {
 		return errors.WithMessage(err, "error creating template output directory")
 	}

run/generate_test.go

@@ -32,7 +32,7 @@ func TestAtomicGenerate(t *testing.T) {
 	}
 	defer os.Remove(filename)
 	contents := "hello world"
-	err = genFile(env, filename, contents, target, nil, ".")
+	err = genFile(env, filename, contents, target, nil, nil, ".")
 	if err == nil {
 		t.Fatal("Unexpected nil error generating contents. Should have failed.")
 	}
@@ -89,3 +89,77 @@ func TestCopyStaticFiles(t *testing.T) {
 		t.Errorf("expected %v to equal %v", newPaths, originPaths)
 	}
 }
+
+func TestNoOverwriteGlobs(t *testing.T) {
+	target := OutputTarget{
+		Filename: template.Must(template.New("").Parse("{{.}}")),
+		Contents: template.Must(template.New("").Parse("{{.}}")),
+	}
+	env := environ.Values{
+		Log: log.New(ioutil.Discard, "", 0),
+	}
+
+	filename := "testfile.out"
+
+	t.Run("file exists and matches glob", func(t *testing.T) {
+		original := []byte("goodbye world")
+		err := ioutil.WriteFile(filename, original, 0600)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer os.Remove(filename)
+
+		err = genFile(env, filename, "hello world", target, []string{"*.out"}, nil, ".")
+		if err != nil {
+			t.Fatalf("Unexpected error generating contents: %s", err)
+		}
+
+		b, err := ioutil.ReadFile(filename)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if !bytes.Equal(b, original) {
+			t.Fatalf("Expected file to be unchanged, but was different.  Expected: %q, got: %q", original, b)
+		}
+
+		t.Run("does not match glob", func(t *testing.T) {
+			content := "hello world"
+			err = genFile(env, filename, content, target, []string{"bob"}, nil, ".")
+			if err != nil {
+				t.Fatalf("Unexpected error generating contents: %s", err)
+			}
+
+			b, err := ioutil.ReadFile(filename)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if !bytes.Equal(b, []byte(content)) {
+				t.Fatalf("Expected file to contain content, but did not.  Expected: %q, got: %q", content, b)
+			}
+		})
+	})
+
+	t.Run("file does not exist but matches glob", func(t *testing.T) {
+		if _, err := os.Stat(filename); err == nil {
+			t.Fatalf("File should not exist, but does.")
+		}
+
+		content := "hello world"
+		err := genFile(env, filename, content, target, []string{"*.out"}, nil, ".")
+		if err != nil {
+			t.Fatalf("Unexpected error generating contents: %s", err)
+		}
+		defer os.Remove(filename)
+
+		b, err := ioutil.ReadFile(filename)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if !bytes.Equal(b, []byte(content)) {
+			t.Fatalf("Expected file to contain content, but did not.  Expected: %q, got: %q", content, b)
+		}
+	})
+}

site/content/cli/configuration.md

@@ -44,7 +44,7 @@ gocog}}} -->
 ConnStr = "dbname=mydb host=127.0.0.1 sslmode=disable user=admin"
 
 # DBType holds the type of db you're connecting to.  Possible values are
-# "postgres" or "mysql". 
+# "postgres" or "mysql".
 DBType = "postgres"
 
 # Schemas holds the names of schemas to generate code for.
@@ -100,6 +100,10 @@ OutputDir = "gnorm"
 # OutputDir
 StaticDir = "static"
 
+# NoOverwriteGlobs is a list of globs
+# (https://golang.org/pkg/path/filepath/#Match). If a filename matches a glob
+# *and* a file exists with that name, it will not be generated.
+NoOverwriteGlobs = ["*.perm.go"]
 
 # TablePaths is a map of output paths to template paths that tells Gnorm how to
 # render and output its table info and where to save that output.  Each template
@@ -184,5 +188,6 @@ StaticDir = "static"
 # .Params value for all templates.
 [Params]
 mySpecialValue = "some value"
+
 ```
 <!-- {{{end}}} -->