Add ability to skip cleaning the output directory

[tylermmorton]

I've run into a snag recently while using Jet's postgres generator. It completely cleans the output directory when it goes to process code generation on a database schema.

The way that my project is set up, I want to generate multiple schemas into the same directory while also having each schema be in its own subpackage:

   /storage
     /schema
       /public
       /computed
       /telemetry

Unfortunately I can't do this when I call ProcessDB multiple times, because it ends up clearing the /schema folder of the files it just generated.

I tried my best to make the proposed changes backwards compatible but I'm open to feedback. I'll maintain a fork of jet for now but I'd love to see this feature merged.

Thanks

[codecov]

Codecov Report

❌ Patch coverage is 11.11111% with 40 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.95%. Comparing base (afc4cee) to head (fc748e9).

Files with missing lines	Patch %	Lines
generator/postgres/postgres_generator.go	0.00%	30 Missing ⚠️
generator/template/process.go	33.33%	8 Missing and 2 partials ⚠️

❌ Your patch check has failed because the patch coverage (11.11%) is below the target coverage (90.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #520      +/-   ##
==========================================
- Coverage   91.35%   90.95%   -0.41%     
==========================================
  Files         136      136              
  Lines        8340     8380      +40     
==========================================
+ Hits         7619     7622       +3     
- Misses        545      581      +36     
- Partials      176      177       +1     

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[go-jet]

because it ends up clearing the /schema folder of the files it just generated.

This shouldn't be the case. If you regenerate public schema computed and telemetry should remain intact.

How are you invoking the generator?

[tylermmorton]

because it ends up clearing the /schema folder of the files it just generated.

This shouldn't be the case. If you regenerate public schema computed and telemetry should remain intact.

How are you invoking the generator?

I'm invoking the generator using Go in a mage script. I only want to generate the SQL builders into this package.

	for _, schemaName := range store.SchemaNames {
		err = postgres.Generate(db, schemaName,
			[]template.Template{
				template.Default(postgres2.Dialect).
					UseSchema(func(schemaMetaData metadata.Schema) template.Schema {
						var skipModel = template.DefaultModel()
						skipModel.Skip = true
						return template.DefaultSchema(schemaMetaData).
							UsePath(filepath.Join("schema")).
							UseModel(skipModel).
							UseSQLBuilder(template.DefaultSQLBuilder().
								UseEnum(func(enum metadata.Enum) template.EnumSQLBuilder {
									skipEnum := template.DefaultEnumSQLBuilder(enum)
									skipEnum.Skip = true
									return skipEnum
								}).
								UseView(func(table metadata.Table) template.ViewSQLBuilder {
									skipView := template.DefaultViewSQLBuilder(table)
									skipView.Skip = true
									return skipView
								}).
								UseTable(func(table metadata.Table) template.TableSQLBuilder {
									skipTable := template.DefaultTableSQLBuilder(table)
									skipTable.Skip = true
									if slices.Contains(skipTables[:], table.Name) {
										return skipTable
									}

									return template.DefaultTableSQLBuilder(table).
										UsePath(schemaName).
										UseFileName(fmt.Sprintf("%s%s.go", strman.SnakeLower(table.Name), genSuffix)).
										UseColumn(func(column metadata.Column) template.TableSQLBuilderColumn {
											return template.DefaultTableSQLBuilderColumn(column)
										})
								}),
							)
					}),
			}
		)
		if err != nil {
			return fmt.Errorf("failed to generate Jet code for schema %s: %w", schemaName, err)
		}
	}

I had played around with calling UsePath("/") on the sql builder template but it hits an error.

[go-jet]

err = postgres.Generate(db, schemaName,

Generate method has this signature:

func Generate(destDir string, dbConn DBConnection, genTemplate ...template.Template) (err error) {

DBConnection has a fields DBName and SchemaName, and the destination directory to generate(and clean) is at destDir/DBName/SchemaName.

There is also GenerateDSN:

func GenerateDSN(dsn, schema, destDir string, templates ...template.Template) error {

, and the destination directory to generate(and clean) is at destDir/DBName/schema(DBName is pulled from dsn string).