Newbie ALERT Trying to run a basic regression model using `p

Question

Newbie ALERT Trying to run a basic regression model using `prefect 2 0` Facing below error ```Traceback most recent call last File home kku work prefect poc env lib python3 8 site packages prefect engine py line 467 in orchestrate flow run result = await run sync in worker thread flow call File home kku work prefect poc env lib python3 8 site packages prefect utilities asyncio py line 52 in run sync in worker thread return await anyio to thread run sync context run call cancellable=True File home kku work prefect poc env lib python3 8 site packages anyio to thread py line 28 in run sync return await get asynclib run sync in worker thread func args cancellable=cancellable File home kku work prefect poc env lib python3 8 site packages anyio backends asyncio py line 818 in run sync in worker thread return await future File home kku work prefect poc env lib python3 8 site packages anyio backends asyncio py line 754 in run result = context run func args File car linearregression py line 104 in do regression X y = get feat and target df car target TypeError cannot unpack non iterable PrefectFuture object ``` It s a simple serial execution where a `flow` function calls different `Task` functions serially very similar to the below tutorial on the official website ```import requests from prefect import flow task task def call api url response = requests get url print response status code return response json task def parse fact response print response fact return flow def api flow url fact json = call api url parse fact fact json return ``` So far I have tried creating a new virtual env and install minimal packages required to run the ML model but had no luck Could you please help me with this

Anna Geller · Answer

Can you share `prefect version` output

Anna Geller · Answer

I couldn t reproduce it can you try this example ```import requests from prefect import flow task task def call api url response = requests get url print response status code return response json task def parse fact response print response BTC return flow def api flow url fact json = call api url parse fact fact json if name == main api flow <https min api cryptocompare com data pricemulti fsyms=BTC amp tsyms=USD> ``` it gives me ```13 13 57 430 | INFO | prefect engine Created flow run jasper groundhog for flow api flow 13 13 57 430 | INFO | Flow run jasper groundhog Using task runner ConcurrentTaskRunner 13 13 57 435 | WARNING | Flow run jasper groundhog No default storage is configured on the server Results from this flow run will be stored in a temporary directory in its runtime environment 13 13 57 457 | INFO | Flow run jasper groundhog Created task run call api 190c7484 0 for task call api 13 13 57 475 | INFO | Flow run jasper groundhog Created task run parse fact b0346046 0 for task parse fact 200 13 13 57 709 | INFO | Task run call api 190c7484 0 Finished in state Completed 13 13 57 725 | INFO | Task run parse fact b0346046 0 Finished in state Completed USD 31412 32 13 13 57 732 | INFO | Flow run jasper groundhog Finished in state Completed All states completed ```

kushagra kumar · Answer

```prefect version 2 0b3```

kushagra kumar · Answer

The tutorial examples works well on my machine It seems when I try to return multiple variables from the function prefect throws an error ```import requests from prefect import flow task task def call api url response = requests get url print response status code return response json response status code task def parse fact response print response BTC return flow def api flow url fact json code = call api url parse fact fact json if name == main api flow <https min api cryptocompare com data pricemulti fsyms=BTC amp tsyms=USD> ``` Error ```13 19 38 116 | INFO | prefect engine Created flow run daffy wildcat for flow api flow 13 19 38 116 | INFO | Flow run daffy wildcat Using task runner ConcurrentTaskRunner 13 19 38 142 | WARNING | Flow run daffy wildcat No default storage is configured on the server Results from this flow run will be stored in a temporary directory in its runtime environment 13 19 38 265 | INFO | Flow run daffy wildcat Created task run call api 190c7484 0 for task call api 13 19 38 286 | ERROR | Flow run daffy wildcat Encountered exception during execution Traceback most recent call last File home kku work prefect poc env lib python3 8 site packages prefect engine py line 467 in orchestrate flow run result = await run sync in worker thread flow call File home kku work prefect poc env lib python3 8 site packages prefect utilities asyncio py line 52 in run sync in worker thread return await anyio to thread run sync context run call cancellable=True File home kku work prefect poc env lib python3 8 site packages anyio to thread py line 28 in run sync return await get asynclib run sync in worker thread func args cancellable=cancellable File home kku work prefect poc env lib python3 8 site packages anyio backends asyncio py line 818 in run sync in worker thread return await future File home kku work prefect poc env lib python3 8 site packages anyio backends asyncio py line 754 in run result = context run func args File test slackeg py line 20 in api flow fact json code = call api url TypeError cannot unpack non iterable PrefectFuture object 200 13 19 38 650 | INFO | Task run call api 190c7484 0 Finished in state Completed 13 19 38 650 | ERROR | Flow run daffy wildcat Finished in state Failed Flow run encountered an exception ``` In My regression POC example too I am trying to return two variables from function

Anna Geller · Answer

Try ```fact json code = call api url result ``` this will work The problem is that you return multiple objects in a task but the task itself returns a PrefectFuture Only by retrieving ` result ` of it you get the actual returned data To assign that to those 2 objects `fact json` and `code` this would need to be the actual data which you can get by adding ` result ` Otherwise you try to unpack PrefectFuture to those two objects which won t work because `call api URL ` returns a single object PrefectFuture `call api url result ` returns the actual data Here is a working example ```import requests from prefect import flow task task def call api url response = requests get url return response json response status code task def parse json response print response BTC task def parse code code print code flow def api flow url resp json resp code = call api url result parse json resp json parse code resp code if name == main api flow <https min api cryptocompare com data pricemulti fsyms=BTC amp tsyms=USD> ```

kushagra kumar · Answer

Many Thanks for the detailed explanation < Anna Geller> slightly smiling face It worked