Fix erniegen no model_config_file (#3321)

* fix

* rm save_pretrained

paddlenlp/transformers/ernie_gen/modeling.py

@@ -25,6 +25,7 @@
 from paddle.utils.download import get_path_from_url
 from paddlenlp.utils.log import logger
 from paddlenlp.transformers import BertPretrainedModel, ElectraPretrainedModel, RobertaPretrainedModel, ErniePretrainedModel
+from .. import PretrainedModel, register_base_model
 
 from ..utils import InitTrackerMeta, fn_args_to_dict
 
@@ -216,7 +217,7 @@ def forward(self, inputs, attn_bias=None, past_cache=None):
 
 
 @six.add_metaclass(InitTrackerMeta)
-class ErnieGenPretrainedModel(object):
+class ErnieGenPretrainedModel(PretrainedModel):
     r"""
     An abstract class for pretrained ErnieGen models. It provides ErnieGen related
     `model_config_file`, `pretrained_init_configuration`, `resource_files_names`,
@@ -389,36 +390,6 @@ def from_pretrained(cls, pretrained_model_name_or_path, *args, **kwargs):
                              weight_path)
         return model
 
-    def save_pretrained(self, save_directory):
-        """
-        Save model configuration and related resources (model state) to files
-        under `save_directory`.
-        Args:
-            save_directory (str): Directory to save files into.
-        """
-        assert os.path.isdir(
-            save_directory
-        ), "Saving directory ({}) should be a directory".format(save_directory)
-        # save model config
-        model_config_file = os.path.join(save_directory, self.model_config_file)
-        model_config = self.init_config
-        # If init_config contains a Layer, use the layer's init_config to save
-        for key, value in model_config.items():
-            if key == "init_args":
-                args = []
-                for arg in value:
-                    args.append(arg.init_config if isinstance(
-                        arg, ErnieGenPretrainedModel) else arg)
-                model_config[key] = tuple(args)
-            elif isinstance(value, ErnieGenPretrainedModel):
-                model_config[key] = value.init_config
-        with io.open(model_config_file, "w", encoding="utf-8") as f:
-            f.write(json.dumps(model_config, ensure_ascii=False))
-        # save model
-        file_name = os.path.join(save_directory,
-                                 list(self.resource_files_names.values())[0])
-        paddle.save(self.state_dict(), file_name)
-
     def _post_init(self, original_init, *args, **kwargs):
         """
         It would be hooked after `__init__` to add a dict including arguments of
@@ -428,7 +399,8 @@ def _post_init(self, original_init, *args, **kwargs):
         self.config = init_dict
 
 
-class ErnieModel(nn.Layer, ErnieGenPretrainedModel):
+@register_base_model
+class ErnieModel(ErnieGenPretrainedModel):
 
     def __init__(self, cfg, name=None):
         """