How to pass array query params to AWS API Gateway?

Question

A Rails API typically likes array query params like this:

example.com?colors[]=cyan&colors[]=magenta&colors[]=yellow&colors[]=black

How would I map that through to a lambda function?

score 24 · Answer 1 · answered Oct 17 '18 at 15:29

Multiple arguments with same name in query string are now supported in API Gateway proxies. They are passed in the multiValueQueryStringParameters dictionary.

E.g.

 GET /api/path/?param=value&param=othervalue&something=thing

Will generate the following request:

{
    "resource": "/{proxy+}",
    "path": "/ap/path/",
    "httpMethod": "GET",
    "queryStringParameters": {
        "param": "othervalue",  # only the last value is kept here
        "something": "thing"
    },
    "multiValueQueryStringParameters": {
        "param": [
            "value",
            "othervalue"
        ],
        "something": [
            "thing"
        ]
    },
    "pathParameters": {
        "proxy": "api/path"
    },
    # etc
}

See documentation.

How do I pass the request to the rails app with the []? thats the only way rails will take it — Danny López, Feb 25 '19 at 20:51
This is the right answer in regards to Lambda and API Gateway. — Chad Johnson, Dec 31 '20 at 21:41

score 11 · Accepted Answer · answered Aug 05 '15 at 22:51

11

A little trial and error shows that it's like this:

example.com?colors=['cyan','magenta','yellow','black']

answered Aug 05 '15 at 22:51

kjs3

5,758
8
34
49

Yes, this is classic `JSON` and that's what `API Gateway` parses. – adamkonrad Aug 06 '15 at 19:46
4

@napalm The problem is that there are lots of frameworks using conventions like this; `columns[0][data]=id&columns[0][name]=ID&columns[0][searchable]=true`! – Renato Gama Sep 08 '15 at 16:41
You should be able to pass and parse the URL fragment in your Lambda. – adamkonrad Sep 08 '15 at 17:58
How would a #foreach on colors look like in this case? – Alex Michel Mar 26 '20 at 11:10
Is there a chance ta pass this list using data mapping template when i use aws type integration to lambda? lambda gets only last value from list... – DevMops Jun 04 '20 at 18:39

Tom Saleeba · Answer 3 · 2018-03-07T22:50:26.643

One thing you can't do is have duplicated query string param keys as per https://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-known-issues.html:

Duplicated headers are not supported.

API Gateway maps the parameters to a JSON object so as long as each item has their own unique key, you won't get any clobbering.

Your option is good but I brainstormed some other options. You could do something like adding indicies in the square brackets:

example.com?colors[0]=cyan&colors[1]=magenta&colors[2]=yellow&colors[3]=black

You could send the query string in the POST body if you were willing to swap from GET to POST. Then you can parse the raw query string yourself. You can even have repeated param keys here because you are parsing it.

?colors=cyan&colors=magenta&colors=yellow&colors=black

Another POST option is to send a JSON array in the POST body. I know POST isn't as easy to work with as GET but it's an option.

["cyan","magenta","yellow","black"]

I found adding indicies to be simple and effective, thanks for the suggestion. — homerjam, Mar 07 '18 at 15:00

score 4 · Answer 4 · edited Jan 27 '22 at 14:10

4

If anyone is using OpenAPI 3.0 spec in AWS Api Gateway then you need to define this in your x-amazon-apigateway-integration like so.

x-amazon-apigateway-integration:
        ...
        requestParameters:
            integration.request.querystring.colors: method.request.multivaluequerystring.colors
        ...

edited Jan 27 '22 at 14:10

Dharman

30,962
25
85
135

answered Jan 27 '22 at 14:04

Sandeep K Nair

2,512
26
26

score 3 · Answer 5 · answered May 30 '17 at 16:13

3

As discussed in @kjs3 answer, API Gateway doesn't support duplicate parameters in the query string or headers. However you can use the single parameter array format.

Supporting duplicate parameter keys+values is something we do want to do, but I don't have an ETA at the moment.

answered May 30 '17 at 16:13

jackko

6,998
26
38

Hello Jack - Thank you for the info! Do you have any new information at the moment? – Yibin Lin May 19 '18 at 21:16
2

Should have support soon. – jackko May 22 '18 at 21:17
Hi @Jack do you have a view on how soon? – CharlesA Aug 07 '18 at 03:44
1

I can see this limitation has been removed from the known issues. Is it still the case? From what I can see only the last occurrence of same-named query params is passed. – Antwan Oct 17 '18 at 14:48

How to pass array query params to AWS API Gateway?

5 Answers5

Linked