Scan enums when using pgx (#386)

While work on adding full support for pgx hasn't started (#28), this change allows sqlc-generated code to be used with pgx's stdlib package github.com/jackc/pgx/v4/stdlib. Note that you'll still see errors if you try using PostgreSQL arrays.

Author: kyleconroy

README.md

@@ -482,8 +482,7 @@ If you need to update a large number of expexted test output in the
 `internal/endtoend/testdata` directory, run the `regenerate.sh` script.
 
 ```
-cd internal/endtoend
-./regenerate.sh
+./scripts/regenerate.sh
 ```
 
 ## Acknowledgements

examples/booktest/mysql/models.go

@@ -340,6 +340,9 @@ func modelImports(r Generateable, settings config.CombinedSettings) fileImports
 	if UsesType(r, "net.HardwareAddr", settings) {
 		std["net"] = struct{}{}
 	}
+	if len(r.Enums(settings)) > 0 {
+		std["fmt"] = struct{}{}
+	}
 
 	// Custom imports
 	pkg := make(map[string]struct{})
@@ -1144,7 +1147,14 @@ const (
 )
 
 func (e *{{.Name}}) Scan(src interface{}) error {
-	*e = {{.Name}}(src.([]byte))
+	switch s := src.(type) {
+	case []byte:
+		*e = {{.Name}}(s)
+	case string:
+		*e = {{.Name}}(s)
+	default:
+		return fmt.Errorf("unsupported scan type for {{.Name}}: %T", src)
+	}
 	return nil
 }
 {{end}}