CODEWITHSUNDEEP
amazon-web-servicesaws-step-functions
Yunhan Zou
Yunhan Zou

Reputation: 489

AWS step functions - reuse previous step's outputs

in AWS step functions I know we can use resultPath to pass the current state's output to the next state along in its inputs. Say I have 3 states A, B, and C, when A finishes executing it passes its input and output to B as input, when B finishes, is there a way to pass B's output along with A's output + input to C as inputs? Please advise, thanks!

Upvotes: 2

Views: 4460

Answers (2)

RaxGG
RaxGG

Reputation: 40

You just have to do the following:

A function:

def lambda_handler(event, context):
    ...
    result = ...
    return {
        "Ainput":event,
        "Aoutput": result
    }

B function:

def lambda_handler(event, context):
    ...
    result = ...
    return {
        "Ainput": event['Ainput'],
        "Aoutput": event['Aoutput'],
        "Boutput": result
    }

C function:

def lambda_handler(event, context):
    Ainput = event['Ainput']
    Aoutput = event['Aoutput']
    Boutput = event['Boutput']

Now you can use that results on your C function as you want.

Upvotes: -1

lynkfox
lynkfox

Reputation: 2400

if you only have a resultPath on your task then it appends the result to the incoming event of that task - So if Task A takes an Input of

{
    TaskAInput: Stuff
}

And has only a resultPath: TaskAOutput then the input for task B will be:

{
    TaskAInput: Stuff
    TaskAOutput: TaskAResult
}

That enters into Task B. If Task B only has a resultPath: TaskBOutput then

{
    TaskAInput: Stuff
    TaskAOutput: TaskAResult
    TaskBOutput: TaskBesult
}

and so on down the chain.

Note. If you attach an outputPath to any of the above steps it will output only that json path from the final combined input and results. If you use an inputPath at all it will cut down the input to just that going forward.

Upvotes: 3

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