fix: Skip empty values so Terraform can use the default value (#3902)

coderd/workspaces.go

@@ -389,6 +389,12 @@ func (api *API) postWorkspacesByOrganization(rw http.ResponseWriter, r *http.Req
 			return xerrors.Errorf("insert workspace: %w", err)
 		}
 		for _, parameterValue := range createWorkspace.ParameterValues {
+			// If the value is empty, we don't want to save it on database so
+			// Terraform can use the default value
+			if parameterValue.SourceValue == "" {
+				continue
+			}
+
 			_, err = db.InsertParameterValue(r.Context(), database.InsertParameterValueParams{
 				ID:                uuid.New(),
 				Name:              parameterValue.Name,

site/src/components/ParameterInput/ParameterInput.tsx

@@ -58,6 +58,7 @@ const ParameterField: React.FC<React.PropsWithChildren<ParameterInputProps>> = (
         id={schema.name}
         size="small"
         defaultValue={schema.default_source_value}
+        placeholder={schema.default_source_value}
         disabled={disabled}
         onChange={(event) => {
           onChange(event.target.value)