Add from_single_file support to ErnieImageTransformer2DModel (#13727)

* Add from_single_file support to ErnieImageTransformer2DModel

* drop redundant copy loop

Author: akshan-main

src/diffusers/loaders/single_file_model.py

@@ -37,6 +37,7 @@
     convert_chroma_transformer_checkpoint_to_diffusers,
     convert_controlnet_checkpoint,
     convert_cosmos_transformer_checkpoint_to_diffusers,
+    convert_ernie_image_transformer_checkpoint_to_diffusers,
     convert_flux2_transformer_checkpoint_to_diffusers,
     convert_flux_transformer_checkpoint_to_diffusers,
     convert_hidream_transformer_to_diffusers,
@@ -118,6 +119,10 @@
         "checkpoint_mapping_fn": convert_chroma_transformer_checkpoint_to_diffusers,
         "default_subfolder": "transformer",
     },
+    "ErnieImageTransformer2DModel": {
+        "checkpoint_mapping_fn": convert_ernie_image_transformer_checkpoint_to_diffusers,
+        "default_subfolder": "transformer",
+    },
     "LTXVideoTransformer3DModel": {
         "checkpoint_mapping_fn": convert_ltx_transformer_checkpoint_to_diffusers,
         "default_subfolder": "transformer",

src/diffusers/loaders/single_file_utils.py

@@ -4170,3 +4170,13 @@ def update_state_dict_inplace(state_dict, old_key: str, new_key: str) -> None:
         update_state_dict_inplace(converted_state_dict, key, new_key)
 
     return converted_state_dict
+
+
+def convert_ernie_image_transformer_checkpoint_to_diffusers(checkpoint, **kwargs):
+    keys = list(checkpoint.keys())
+
+    for k in keys:
+        if "model.diffusion_model." in k:
+            checkpoint[k.replace("model.diffusion_model.", "")] = checkpoint.pop(k)
+
+    return checkpoint

src/diffusers/models/transformers/transformer_ernie_image.py

@@ -25,7 +25,7 @@
 import torch.nn.functional as F
 
 from ...configuration_utils import ConfigMixin, register_to_config
-from ...loaders import PeftAdapterMixin
+from ...loaders import FromOriginalModelMixin, PeftAdapterMixin
 from ...utils import BaseOutput, logging
 from ..attention import AttentionModuleMixin
 from ..attention_dispatch import dispatch_attention_fn
@@ -289,7 +289,7 @@ def forward(self, x: torch.Tensor, conditioning: torch.Tensor) -> torch.Tensor:
         return x
 
 
-class ErnieImageTransformer2DModel(ModelMixin, ConfigMixin, PeftAdapterMixin):
+class ErnieImageTransformer2DModel(ModelMixin, ConfigMixin, PeftAdapterMixin, FromOriginalModelMixin):
     _supports_gradient_checkpointing = True
     _repeated_blocks = ["ErnieImageSharedAdaLNBlock"]