Repository: gradio-app/gradio

Issue:
Gradio 3.0 cannot load interfaces from Gradio 2
### Describe the bug

Loading an interface of a Space that has <3 from a Space with Gradio 3.0 breaks

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Reproduction

https://huggingface.co/spaces/osanseviero/mix_match_gradio

### Screenshot

_No response_

### Logs

```shell
Fetching interface from: https://huggingface.co/spaces/mrm8488/GPT-J-6B
/home/user/.local/lib/python3.8/site-packages/gradio/deprecation.py:40: UserWarning: `optional` parameter is deprecated, and it has no effect
  warnings.warn(value)
/home/user/.local/lib/python3.8/site-packages/gradio/deprecation.py:43: UserWarning: You have unused kwarg parameters in Textbox, please remove them: {'default': ''}
  warnings.warn(
/home/user/.local/lib/python3.8/site-packages/gradio/interface.py:282: UserWarning: Currently, only the 'default' theme is supported.
  warnings.warn("Currently, only the 'default' theme is supported.")
Fetching interface from: https://huggingface.co/spaces/akhaliq/T0pp
Traceback (most recent call last):
  File "app.py", line 4, in <module>
    iface2 = gr.Interface.load("spaces/akhaliq/T0pp")
  File "/home/user/.local/lib/python3.8/site-packages/gradio/interface.py", line 90, in load
    return super().load(name=name, src=src, api_key=api_key, alias=alias, **kwargs)
  File "/home/user/.local/lib/python3.8/site-packages/gradio/blocks.py", line 518, in load
    return external.load_blocks_from_repo(name, src, api_key, alias, **kwargs)
  File "/home/user/.local/lib/python3.8/site-packages/gradio/external.py", line 34, in load_blocks_from_repo
    blocks: gradio.Blocks = factory_methods[src](name, api_key, alias, **kwargs)
  File "/home/user/.local/lib/python3.8/site-packages/gradio/external.py", line 309, in get_spaces
    return get_spaces_blocks(model_name, config)
  File "/home/user/.local/lib/python3.8/site-packages/gradio/external.py", line 349, in get_spaces_blocks
    return gradio.Blocks.from_config(config, fns)
  File "/home/user/.local/lib/python3.8/site-packages/gradio/blocks.py", line 311, in from_config
    event_method(fn=fn, **dependency)
  File "/home/user/.local/lib/python3.8/site-packages/gradio/blocks.py", line 471, in __exit__
    self.config = self.get_config_file()
  File "/home/user/.local/lib/python3.8/site-packages/gradio/blocks.py", line 440, in get_config_file
    "props": utils.delete_none(block.get_config())
  File "/home/user/.local/lib/python3.8/site-packages/gradio/components.py", line 3590, in get_config
    "components": [component.get_block_name() for component in self.components],
  File "/home/user/.local/lib/python3.8/site-packages/gradio/components.py", line 3590, in <listcomp>
    "components": [component.get_block_name() for component in self.components],
AttributeError: 'str' object has no attribute 'get_block_name'
```
```


### System Info

```shell
Google Chrome, Space using Gradio 3.0.9
```


### Severity

serious, but I can work around it

Comments:

Patch:
diff --git a/gradio/blocks.py b/gradio/blocks.py
index 6cb19350f..0b0a434e2 100644
--- a/gradio/blocks.py
+++ b/gradio/blocks.py
@@ -1,11 +1,13 @@
 from __future__ import annotations
 
+import copy
 import getpass
 import inspect
 import os
 import random
 import sys
 import time
+import warnings
 import webbrowser
 from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Tuple
 
@@ -310,8 +312,91 @@ class Blocks(BlockContext):
                     event_method = getattr(original_mapping[target], trigger)
                     event_method(fn=fn, **dependency)
 
+            # Allows some use of Interface-specific methods with loaded Spaces
+            blocks.predict = [fns[0]]
+            dependency = blocks.dependencies[0]
+            blocks.input_components = [blocks.blocks[i] for i in dependency["inputs"]]
+            blocks.output_components = [blocks.blocks[o] for o in dependency["outputs"]]
+
+        blocks.api_mode = True
         return blocks
 
+    def __call__(self, *params, fn_index=0):
+        """
+        Allows Blocks objects to be called as functions
+        Parameters:
+        *params: the parameters to pass to the function
+        fn_index: the index of the function to call (defaults to 0, which for Interfaces, is the default prediction function)
+        """
+        dependency = self.dependencies[fn_index]
+        block_fn = self.fns[fn_index]
+
+        if self.api_mode:
+            serialized_params = []
+            for i, input_id in enumerate(dependency["inputs"]):
+                block = self.blocks[input_id]
+                if getattr(block, "stateful", False):
+                    raise ValueError(
+                        "Cannot call Blocks object as a function if any of"
+                        " the inputs are stateful."
+                    )
+                else:
+                    serialized_input = block.serialize(params[i], True)
+                    serialized_params.append(serialized_input)
+        else:
+            serialized_params = params
+
+        processed_input = self.preprocess_data(fn_index, serialized_params, None)
+
+        if inspect.iscoroutinefunction(block_fn.fn):
+            raise ValueError(
+                "Cannot call Blocks object as a function if the function is a coroutine"
+            )
+        else:
+            predictions = block_fn.fn(*processed_input)
+
+        output = self.postprocess_data(fn_index, predictions, None)
+
+        if self.api_mode:
+            output_copy = copy.deepcopy(output)
+            deserialized_output = []
+            for o, output_id in enumerate(dependency["outputs"]):
+                block = self.blocks[output_id]
+                if getattr(block, "stateful", False):
+                    raise ValueError(
+                        "Cannot call Blocks object as a function if any of"
+                        " the outputs are stateful."
+                    )
+                else:
+                    deserialized = block.deserialize(output_copy[o])
+                    deserialized_output.append(deserialized)
+        else:
+            deserialized_output = output
+
+        if len(deserialized_output) == 1:
+            return deserialized_output[0]
+        return deserialized_output
+
+    def __str__(self):
+        return self.__repr__()
+
+    def __repr__(self):
+        num_backend_fns = len([d for d in self.dependencies if d["backend_fn"]])
+        repr = f"Gradio Blocks instance: {num_backend_fns} backend functions"
+        repr += "\n" + "-" * len(repr)
+        for d, dependency in enumerate(self.dependencies):
+            if dependency["backend_fn"]:
+                repr += f"\nfn_index={d}"
+                repr += "\n inputs:"
+                for input_id in dependency["inputs"]:
+                    block = self.blocks[input_id]
+                    repr += "\n |-{}".format(str(block))
+                repr += "\n outputs:"
+                for output_id in dependency["outputs"]:
+                    block = self.blocks[output_id]
+                    repr += "\n |-{}".format(str(block))
+        return repr
+
     def render(self):
         if Context.root_block is not None:
             Context.root_block.blocks.update(self.blocks)
@@ -320,22 +405,7 @@ class Blocks(BlockContext):
         if Context.block is not None:
             Context.block.children.extend(self.children)
 
-    async def process_api(
-        self,
-        data: PredictBody,
-        username: str = None,
-        state: Optional[Dict[int, any]] = None,
-    ) -> Dict[str, Any]:
-        """
-        Processes API calls from the frontend.
-        Parameters:
-            data: data recieved from the frontend
-            username: name of user if authentication is set up
-            state: data stored from stateful components for session
-        Returns: None
-        """
-        raw_input = data.data
-        fn_index = data.fn_index
+    def preprocess_data(self, fn_index, raw_input, state):
         block_fn = self.fns[fn_index]
         dependency = self.dependencies[fn_index]
 
@@ -349,14 +419,24 @@ class Blocks(BlockContext):
                     processed_input.append(block.preprocess(raw_input[i]))
         else:
             processed_input = raw_input
+        return processed_input
+
+    async def call_function(self, fn_index, processed_input):
+        """Calls and times function with given index and preprocessed input."""
+        block_fn = self.fns[fn_index]
+
         start = time.time()
         if inspect.iscoroutinefunction(block_fn.fn):
-            predictions = await block_fn.fn(*processed_input)
+            prediction = await block_fn.fn(*processed_input)
         else:
-            predictions = await run_in_threadpool(block_fn.fn, *processed_input)
+            prediction = await run_in_threadpool(block_fn.fn, *processed_input)
         duration = time.time() - start
-        block_fn.total_runtime += duration
-        block_fn.total_runs += 1
+        return prediction, duration
+
+    def postprocess_data(self, fn_index, predictions, state):
+        block_fn = self.fns[fn_index]
+        dependency = self.dependencies[fn_index]
+
         if type(predictions) is dict and len(predictions) > 0:
             keys_are_blocks = [isinstance(key, Block) for key in predictions.keys()]
             if all(keys_are_blocks):
@@ -375,6 +455,7 @@ class Blocks(BlockContext):
                 )
         if len(dependency["outputs"]) == 1:
             predictions = (predictions,)
+
         if block_fn.postprocess:
             output = []
             for i, output_id in enumerate(dependency["outputs"]):
@@ -410,6 +491,34 @@ class Blocks(BlockContext):
 
         else:
             output = predictions
+        return output
+
+    async def process_api(
+        self,
+        fn_index: int,
+        raw_input: List[Any],
+        username: str = None,
+        state: Optional[Dict[int, any]] = None,
+    ) -> Dict[str, Any]:
+        """
+        Processes API calls from the frontend. First preprocesses the data,
+        then runs the relevant function, then postprocesses the output.
+        Parameters:
+            data: data recieved from the frontend
+            username: name of user if authentication is set up
+            state: data stored from stateful components for session
+        Returns: None
+        """
+        block_fn = self.fns[fn_index]
+
+        processed_input = self.preprocess_data(fn_index, raw_input, state)
+
+        predictions, duration = await self.call_function(fn_index, processed_input)
+        block_fn.total_runtime += duration
+        block_fn.total_runs += 1
+
+        output = self.postprocess_data(fn_index, predictions, state)
+
         return {
             "data": output,
             "duration": duration,
diff --git a/gradio/components.py b/gradio/components.py
index 982378836..8bff6374c 100644
--- a/gradio/components.py
+++ b/gradio/components.py
@@ -11,12 +11,11 @@ import numbers
 import operator
 import os
 import shutil
-import sys
 import tempfile
 import warnings
 from copy import deepcopy
 from types import ModuleType
-from typing import Any, Callable, Dict, List, Optional, Tuple, Type
+from typing import Any, Callable, Dict, List, Optional, Tuple
 
 import matplotlib.figure
 import numpy as np
@@ -26,7 +25,7 @@ from ffmpy import FFmpeg
 from markdown_it import MarkdownIt
 
 from gradio import media_data, processing_utils
-from gradio.blocks import Block, BlockContext
+from gradio.blocks import Block
 from gradio.events import (
     Changeable,
     Clearable,
@@ -889,7 +888,7 @@ class CheckboxGroup(Changeable, IOComponent):
 
     def __init__(
         self,
-        choices: List[str],
+        choices: List[str] = None,
         *,
         value: List[str] = None,
         type: str = "value",
@@ -909,7 +908,7 @@ class CheckboxGroup(Changeable, IOComponent):
         show_label (bool): if True, will display label.
         visible (bool): If False, component will be hidden.
         """
-        self.choices = choices
+        self.choices = choices or []
         self.cleared_value = []
         self.type = type
         self.value = self.postprocess(value)
@@ -1052,7 +1051,7 @@ class Radio(Changeable, IOComponent):
 
     def __init__(
         self,
-        choices: List[str],
+        choices: List[str] = None,
         *,
         value: Optional[str] = None,
         type: str = "value",
@@ -1072,7 +1071,7 @@ class Radio(Changeable, IOComponent):
         show_label (bool): if True, will display label.
         visible (bool): If False, component will be hidden.
         """
-        self.choices = choices
+        self.choices = choices or []
         self.type = type
         self.test_input = self.choices[0] if len(self.choices) else None
         self.value = self.postprocess(value)
@@ -1197,7 +1196,7 @@ class Dropdown(Radio):
 
     def __init__(
         self,
-        choices: List[str],
+        choices: List[str] = None,
         *,
         value: Optional[str] = None,
         type: str = "value",
@@ -1678,7 +1677,8 @@ class Video(Changeable, Clearable, Playable, IOComponent):
             return file_name
 
     def serialize(self, x, called_directly):
-        raise NotImplementedError()
+        data = processing_utils.encode_url_or_file_to_base64(x)
+        return {"name": x, "data": data, "is_example": False}
 
     def save_flagged(self, dir, label, data, encryption_key):
         """
@@ -1712,7 +1712,8 @@ class Video(Changeable, Clearable, Playable, IOComponent):
         }
 
     def deserialize(self, x):
-        return processing_utils.decode_base64_to_file(x).name
+        file = processing_utils.decode_base64_to_file(x["data"])
+        return file.name
 
     def style(
         self,
@@ -2001,7 +2002,8 @@ class Audio(Changeable, Clearable, Playable, Streamable, IOComponent):
         return processing_utils.encode_url_or_file_to_base64(y)
 
     def deserialize(self, x):
-        return processing_utils.decode_base64_to_file(x).name
+        file = processing_utils.decode_base64_to_file(x["data"])
+        return file.name
 
     def stream(
         self,
@@ -2209,7 +2211,8 @@ class File(Changeable, Clearable, IOComponent):
             }
 
     def deserialize(self, x):
-        return processing_utils.decode_base64_to_file(x).name
+        file = processing_utils.decode_base64_to_file(x["data"])
+        return file.name
 
     def restore_flagged(self, dir, data, encryption_key):
         return self.restore_flagged_file(dir, data, encryption_key)
diff --git a/gradio/external.py b/gradio/external.py
index b545cf216..618d0f285 100644
--- a/gradio/external.py
+++ b/gradio/external.py
@@ -323,12 +323,12 @@ def get_spaces_blocks(model_name, config):
     headers = {"Content-Type": "application/json"}
 
     fns = []
-    for _dependency in config["dependencies"]:
-        if _dependency["backend_fn"]:
+    for d, dependency in enumerate(config["dependencies"]):
+        if dependency["backend_fn"]:
 
-            def get_fn(dependency):
+            def get_fn(outputs, fn_index):
                 def fn(*data):
-                    data = json.dumps({"data": data})
+                    data = json.dumps({"data": data, "fn_index": fn_index})
                     response = requests.post(api_url, headers=headers, data=data)
                     result = json.loads(response.content.decode("utf-8"))
                     try:
@@ -337,13 +337,14 @@ def get_spaces_blocks(model_name, config):
                         raise KeyError(
                             f"Could not find 'data' key in response from external Space. Response received: {result}"
                         )
-                    if len(dependency["outputs"]) == 1:
+                    if len(outputs) == 1:
                         output = output[0]
                     return output
 
                 return fn
 
-            fns.append(get_fn(deepcopy(_dependency)))
+            fn = get_fn(deepcopy(dependency["outputs"]), d)
+            fns.append(fn)
         else:
             fns.append(None)
     return gradio.Blocks.from_config(config, fns)
diff --git a/gradio/mix.py b/gradio/mix.py
index 81f5cebbc..9eb6e9bf7 100644
--- a/gradio/mix.py
+++ b/gradio/mix.py
@@ -1,6 +1,8 @@
 """
 Ways to transform interfaces to produce new interfaces
 """
+import warnings
+
 import gradio
 
 
@@ -22,6 +24,10 @@ class Parallel(gradio.Interface):
         outputs = []
 
         for io in interfaces:
+            if not (isinstance(io, gradio.Interface)):
+                warnings.warn(
+                    "Parallel may not work properly with non-Interface objects."
+                )
             fns.extend(io.predict)
             outputs.extend(io.output_components)
 
@@ -52,7 +58,13 @@ class Series(gradio.Interface):
         Returns:
         (Interface): an Interface object connecting the given models
         """
-        fns = [io.predict for io in interfaces]
+        fns = []
+        for io in interfaces:
+            if not (isinstance(io, gradio.Interface)):
+                warnings.warn(
+                    "Series may not work properly with non-Interface objects."
+                )
+            fns.append(io.predict)
 
         def connected_fn(
             *data,
diff --git a/gradio/routes.py b/gradio/routes.py
index ebee2c8a2..32ca616b6 100644
--- a/gradio/routes.py
+++ b/gradio/routes.py
@@ -278,7 +278,11 @@ class App(FastAPI):
             else:
                 session_state = {}
             try:
-                output = await app.blocks.process_api(body, username, session_state)
+                raw_input = body.data
+                fn_index = body.fn_index
+                output = await app.blocks.process_api(
+                    fn_index, raw_input, username, session_state
+                )
             except BaseException as error:
                 if app.blocks.show_error:
                     traceback.print_exc()
diff --git a/ui/packages/upload/src/Upload.svelte b/ui/packages/upload/src/Upload.svelte
index 5281171a9..708154f1d 100644
--- a/ui/packages/upload/src/Upload.svelte
+++ b/ui/packages/upload/src/Upload.svelte
@@ -10,7 +10,7 @@
 	export let click: boolean = true;
 	export let center: boolean = true;
 	export let flex: boolean = true;
-	export let file_count: string;
+	export let file_count: string = "single";
 
 	let hidden_upload: HTMLInputElement;
 
@@ -46,7 +46,10 @@
 					  }
 					: (this.result as string);
 				if (all_file_data.length === files.length) {
-					dispatch("load", all_file_data);
+					dispatch(
+						"load",
+						file_count == "single" ? all_file_data[0] : all_file_data
+					);
 				}
 			};
 		});


Test patch:
diff --git a/test/test_components.py b/test/test_components.py
index f8a24e386..67948975a 100644
--- a/test/test_components.py
+++ b/test/test_components.py
@@ -843,9 +843,7 @@ class TestAudio(unittest.TestCase):
             },
         )
         self.assertTrue(
-            audio_output.deserialize(
-                deepcopy(media_data.BASE64_AUDIO)["data"]
-            ).endswith(".wav")
+            audio_output.deserialize(deepcopy(media_data.BASE64_AUDIO)).endswith(".wav")
         )
         with tempfile.TemporaryDirectory() as tmpdirname:
             to_save = audio_output.save_flagged(
@@ -1179,8 +1177,10 @@ class TestVideo(unittest.TestCase):
         self.assertIsNotNone(video_input.preprocess(x_video))
         video_input = gr.Video(format="avi")
         self.assertEqual(video_input.preprocess(x_video)[-3:], "avi")
-        with self.assertRaises(NotImplementedError):
-            video_input.serialize(x_video, True)
+
+        self.assertEqual(
+            video_input.serialize(x_video["name"], True)["data"], x_video["data"]
+        )
 
         # Output functionalities
         y_vid_path = "test/test_files/video_sample.mp4"
@@ -1191,9 +1191,7 @@ class TestVideo(unittest.TestCase):
             )
         )
         self.assertTrue(
-            video_output.deserialize(
-                deepcopy(media_data.BASE64_VIDEO)["data"]
-            ).endswith(".mp4")
+            video_output.deserialize(deepcopy(media_data.BASE64_VIDEO)).endswith(".mp4")
         )
         with tempfile.TemporaryDirectory() as tmpdirname:
             to_save = video_output.save_flagged(