Add transformation of SQL DB read error so HandleNotFound works (#3396) (#1972)

Signed-off-by: Modular Magician <[email protected]>

Author: modular-magician

.changelog/3396.txt

@@ -0,0 +1,3 @@
+```release-note:bug
+sql: fixed behaviour in `google_sql_database` when the parent instance is deleted, removing it from state
+```

google-beta/resource_sql_database.go

@@ -176,7 +176,7 @@ func resourceSQLDatabaseRead(d *schema.ResourceData, meta interface{}) error {
 	}
 	res, err := sendRequest(config, "GET", project, url, nil)
 	if err != nil {
-		return handleNotFoundError(err, d, fmt.Sprintf("SQLDatabase %q", d.Id()))
+		return handleNotFoundError(transformSQLDatabaseReadError(err), d, fmt.Sprintf("SQLDatabase %q", d.Id()))
 	}
 
 	if err := d.Set("project", project); err != nil {

google-beta/sql_utils.go

@@ -0,0 +1,26 @@
+package google
+
+import (
+	"log"
+	"strings"
+
+	"github.com/hashicorp/errwrap"
+	"google.golang.org/api/googleapi"
+)
+
+func transformSQLDatabaseReadError(err error) error {
+	if gErr, ok := errwrap.GetType(err, &googleapi.Error{}).(*googleapi.Error); ok {
+		if gErr.Code == 400 && strings.Contains(gErr.Message, "Invalid request since instance is not running") {
+			// This error occurs when attempting a GET after deleting the sql database and sql instance. It leads to to
+			// inconsistent behavior as handleNotFoundError(...) expects an error code of 404 when a resource does not
+			// exist. To get the desired behavior from handleNotFoundError, modify the return code to 404 so that
+			// handleNotFoundError(...) will treat this as a NotFound error
+			gErr.Code = 404
+		}
+
+		log.Printf("[DEBUG] Transformed SQLDatabase error")
+		return gErr
+	}
+
+	return err
+}