Azure function prints out the http error message - azure

Question

I have been trying to execute an azure function. The function does some calculation and returns a json response. If I just print out the json, it gets printed, but the log also contain the below error statement:
2020-06-05T05:03:35.256 [Error] Executed 'Functions.curvefitting' (Failed, Id=8b47fa39-746e-4153-9451-d18bb79ed4cd)
Unable to cast object of type 'System.Byte[]' to type 'Microsoft.AspNetCore.Http.HttpRequest'.
I have coded my main function as:
import azure.functions as af
def main(myblob: af.InputStream) -> str:
json_response = <some calculatios>
return json_response
And here's my function.json file:
{
"scriptFile": "xyz.py",
"entryPoint": "main",
"bindings":[
{
"authLevel": "function",
"type": "blobTrigger",
"direction": "in",
"name": "myblob",
"path": "xyz.xlsx",
"connection": "AzureWebJobsStorage",
"methods":[
"get",
"post"
]
},
{
"type": "http",
"direction": "out",
"name": "$return"
}
]
}
Please let me know what I am doing wrong here. I am new to azure functions.

Answer 1

Based on your Json file it looks like you started out with an HttpTriggered function, but you changed it to a BlobTriggered function. Your input binding defines a blobTrigger, but there's also methods there (which are HTTP methods) and the output binding is an HTTP binding.
Most important question is: what are you trying to achieve? If this should be an HttpTriggered function that uses a Blob as input, define an HttpTrigger and an input binding for the blob.
This would be an example of an HttpTriggered Function with an input Blob binding:
{
"scriptFile": "xyz.py",
"entryPoint": "main",
"bindings":[
{
"authLevel": "anonymous",
"type": "httpTrigger",
"direction": "in",
"name": "req"
},
{
"name": "myblob",
"type": "blob",
"dataType": "binary",
"path": "xyz.xlsx",
"connection": "MyStorageConnectionAppSetting",
"direction": "in"
},
{
"type": "http",
"direction": "out",
"name": "res"
}
]
}
Your main entry point would look something like
def main(req: func.HttpRequest, myblob: func.InputStream) -> func.HttpResponse:
For more information and examples, see Azure Blob storage input binding for Azure Functions and Azure Functions HTTP trigger.