Urlencoded GET parameters

[random1st]

I have used Dynamic Rest library with additional filtering. If I use standard filter expression like as '/api/receipt-image/?filter{receipt}=1' I get empty response. It is properly works with '/api/receipt-image/?filter%7Breceipt%7D=1'. I think it concerned event's parsing.

[scoates]

Hi there.
This is not a Zappa problem, but it seems to be a limitation of the API Gateway (similar to foo=1&foo=2 not working on APIGW).

Consider this Lambda function (no Zappa):

from __future__ import print_function

import json

print('Loading function')


def respond(err, res=None):
    return {
        'statusCode': '400' if err else '200',
        'body': err.message if err else json.dumps(res),
        'headers': {
            'Content-Type': 'application/json',
        },
    }


def lambda_handler(event, context):
    print("Received event: " + json.dumps(event, indent=2))
    
    return respond(None, event)

Wired this up to apigw and hit it with curl:

curl -s 'https://REDACTED.execute-api.us-east-1.amazonaws.com/prod/sc-test3?filter{receipt}=1' | python -mjson.tool

The relevant output is:

    "queryStringParameters": {
        "filterreceipt": "1"
    },

Unfortunately, I don't believe there's anything we can do to fix this in Zappa.

@Miserlou: I suggest close.

[scoates]

Addendum: please ask AWS support to request a fix from the apigw team. If enough of us do this, it might work.

[random1st]

You are not right. I fixed it when I work with API Gateway directly. I encode querystring with base64 in API Gateway templates mapping and decode when params received in lambda event. It works for me and i think no reason not to work for you

[scoates]

Can you elaborate? How?

[random1st]

This is part of my AG template

"resource_path" : "$context.resourcePath",
"http_method" : "$context.httpMethod",
"headers": {
    #foreach($param in $input.params().header.keySet())
    "$param": "$util.escapeJavaScript($input.params().header.get($param))" #if($foreach.hasNext),#end

    #end
  },
"query_params": {
    #foreach($param in $input.params().querystring.keySet())
    "$param": "$util.base64Encode($input.params().querystring.get($param))" #if($foreach.hasNext),#end

    #end
  },
"path_params": {
    #foreach($param in $input.params().path.keySet())
    "$param": "$util.escapeJavaScript($input.params().path.get($param))" #if($foreach.hasNext),#end

    #end
  }
}```


In lambda handler

if 'query_params' in event:
        event['query_params'] = {
            k: base64.b64decode(v).decode("utf-8")
            for k, v in event.get('query_params', {}).iteritems()
            }

[scoates]

Hi. I finally had a chance to look into this today. Are you sure that Apache Velocity template turns ?filter{receipt}=1 into base64 encoding for the key name?

I couldn't get it to work directly with apigw+lambda with this template (there's a syntax error at the start of your example, but I think that's just missing a {). Looks like maybe you're only encoding/decoding the values, not the keys?

[scoates]

Update: even a straight-up "sc_test" : "$input.params().querystring", in the Velocity template gives event.get('sc_test') == '{filterreceipt=1}' in raw (non-Zappa) lambda, for ?filter{receipt}=1.

Very interested in how you accomplished this, if it works for you. (-:

[scoates]

Going to close this one. Please reopen if there is new information.

[scoates]

Related: the REQUEST type might allow us to do this. More info: in #1159.