From b6609915e0291183655a0e126975636731fe6092 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=96mer=20Faruk=20=C3=96zdemir?= <farukozderim@gmail.com>
Date: Tue, 1 Mar 2022 12:45:24 +0300
Subject: [PATCH] add change and save events on backend

---
 gradio/__init__.py |  1 -
 gradio/blocks.py   | 58 +++++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/gradio/__init__.py b/gradio/__init__.py
index 8a9b9b4ab7..c6c85cb55b 100644
--- a/gradio/__init__.py
+++ b/gradio/__init__.py
@@ -11,6 +11,5 @@ from gradio.interface import Interface, close_all, reset_all
 from gradio.mix import Parallel, Series
 from gradio.routes import get_state, set_state
 from gradio.static import Button, Markdown
-
 current_pkg_version = pkg_resources.require("gradio")[0].version
 __version__ = current_pkg_version
diff --git a/gradio/blocks.py b/gradio/blocks.py
index 53b1745f0e..7aaafba182 100644
--- a/gradio/blocks.py
+++ b/gradio/blocks.py
@@ -3,7 +3,7 @@ from typing import TYPE_CHECKING, Any, Callable, Dict, List, Optional, Tuple
 from gradio import utils
 from gradio.context import Context
 from gradio.launchable import Launchable
-
+from gradio.component import Component
 
 class Block:
     def __init__(self):
@@ -30,6 +30,62 @@ class Block:
             }
         )
 
+    def change(self, fn: str, inputs: List[Component], outputs: List[Component]) -> None:
+        """
+        Adds change event to the dependencies.
+
+        Whenever one of the inputs changes the function is triggered.
+
+        Parameters:
+            fn:
+            inputs:
+            outputs:
+
+        Returns: None
+
+        """
+        if not isinstance(inputs, list):
+            inputs = [inputs]
+        if not isinstance(outputs, list):
+            outputs = [outputs]
+        Context.root_block.fns.append(fn)
+        Context.root_block.dependencies.append(
+            {
+                "targets": [self._id],
+                "trigger": "change",
+                "inputs": [block._id for block in inputs],
+                "outputs": [block._id for block in outputs],
+            }
+        )
+
+    def save(self, fn: str, inputs: List[Component], outputs: List[Component]) -> None:
+        """
+        Adds save event to the dependencies.
+
+        Whenever one of the inputs is saved, function is triggered.
+
+        Parameters:
+            fn: function name
+            inputs: input list
+            outputs: output list
+
+        Returns: None
+
+        """
+        if not isinstance(inputs, list):
+            inputs = [inputs]
+        if not isinstance(outputs, list):
+            outputs = [outputs]
+        Context.root_block.fns.append(fn)
+        Context.root_block.dependencies.append(
+            {
+                "targets": [self._id],
+                "trigger": "save",
+                "inputs": [block._id for block in inputs],
+                "outputs": [block._id for block in outputs],
+            }
+        )
+
 
 class BlockContext(Block):
     def __init__(self):