I'm trying to cache and retrieve an object using the cache.set() and cache.get() methods, but I'm having some trouble getting it to work properly. I use the .set() method to cache an object (obj1) that has another object (obj2) as its attribute. After retrieving the cached object (obj1) using cache.get(), I am not able to access the attributes of obj2. I'm getting an AttributeError: 'CustomDataFrame' object has no attribute '_var1'.
Expected behavior:
Before caching, var1: Remember me
After caching, var1: Remember me
Actual behavior:
Before caching, var1: Remember me
AttributeError: 'CustomDataFrame' object has no attribute 'var1'.
Minimal reproducible example:
from flask import Flask
from flask_caching import Cache
import pandas as pd
app = Flask(__name__)
# Configure Flask-Cache
app.config["CACHE_TYPE"] = "filesystem"
app.config["CACHE_DIR"] = "/tmp"
app.config["CACHE_DEFAULT_TIMEOUT"] = 600
cache = Cache(app)
class CustomDataFrame(pd.DataFrame):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self.var1 = None
def custom_method(self, arg1, arg2):
# perform some custom operation
pass
class DataFrameManager():
def __init__(self, df: CustomDataFrame):
self.df = df
def custom_method(self, arg1, arg2):
# perform some custom operation
pass
# Set up a route that uses caching
@app.route("/")
def set_and_get_route():
# Create custom object
data = {'name': ['Alice', 'Bob'], 'age': [24, 32]}
df = CustomDataFrame(data)
df.var1 = "remember me"
df_manager = DataFrameManager(df)
# Use .set() to store a value in the cache
print(f"Before caching, var1: {df_manager.df.var1}")
cache.set("df_manager", df_manager)
# Use .get() to retrieve a value from the cache
retrieved_df_manager = cache.get("df_manager")
print(f"After caching, var1: {retrieved_df_manager.df.var1}")
return "dummy"
if __name__ == "__main__":
app.run()
