}
            final File jspFile = new File(getServletContext().getRealPath(path));
            if (!jspFile.exists()) {
                throwValidationError(messages -> messages.addErrorsDesignJspFileDoesNotExist(GLOBAL), this::asListHtml);
            }
            return jspFile;
        } catch (final UnsupportedEncodingException e) {

This gives you a lot of flexibility. You can return any data type, override any data declaration or validation, etc.

## Using the `jsonable_encoder` in a `Response` { #using-the-jsonable-encoder-in-a-response }

Because **FastAPI** doesn't make any changes to a `Response` you return, you have to make sure its contents are ready for it.

For example, if you need to store it in a database.

For that, **FastAPI** provides a `jsonable_encoder()` function.

## Using the `jsonable_encoder` { #using-the-jsonable-encoder }

Let's imagine that you have a database `fake_db` that only receives JSON compatible data.

For example, it doesn't receive `datetime` objects, as those are not compatible with JSON.

                    designJspFileNameMap.entrySet().stream().forEach(e -> {
                        final File jspFile = getDesignJspFile("/WEB-INF/view" + key + "/" + e.getValue());
                        if (!jspFile.exists()) {
                            jspFile.getParentFile().mkdirs();
                            final File baseJspFile = getDesignJspFile("/WEB-INF/view/" + e.getValue());

            return null;
        }

        @Override
        public jakarta.servlet.ServletRegistration.Dynamic addJspFile(String servletName, String jspFile) {
            return null;
        }

        @Override
        public <T extends jakarta.servlet.Servlet> T createServlet(Class<T> clazz) {
            return null;
        }

        @Override

            return null;
        }

        @Override
        public jakarta.servlet.ServletRegistration.Dynamic addJspFile(String servletName, String jspFile) {
            return null;
        }

        @Override
        public <T extends jakarta.servlet.Servlet> T createServlet(Class<T> clazz) {
            return null;
        }

        @Override

            return null;
        }

        @Override
        public jakarta.servlet.ServletRegistration.Dynamic addJspFile(String servletName, String jspFile) {
            return null;
        }

        @Override
        public <T extends jakarta.servlet.Servlet> T createServlet(Class<T> clazz) {
            return null;
        }

        @Override

        * Before this, the return content was first passed through `jsonable_encoder` to ensure it was a "jsonable" object, like a `dict`, instead of an arbitrary object with attributes (like an ORM model). That's why you should make sure to update your Pydantic models for objects with attributes to use `orm_mode = True`.