How to add Alamofire URL parameters

Question

I have a working scenario using Postman passing in URL parameters. Now when I try to do it via Alamofire in Swift, it does not work.

How would you create this url in Alamofire? http://localhost:8080/?test=123

    _url = "http://localhost:8080/"
    let parameters: Parameters = [
        "test": "123"
        ]

    Alamofire.request(_url,
                      method: .post,
                      parameters: parameters,
                      encoding: URLEncoding.default,
                      headers: headers

score 121 · Accepted Answer · answered Apr 07 '17 at 16:22

121

The problem is that you're using URLEncoding.default. Alamofire interprets URLEncoding.default differently depending on the HTTP method you're using.

For GET, HEAD, and DELETE requests, URLEncoding.default encodes the parameters as a query string and adds it to the URL, but for any other method (such as POST) the parameters get encoded as a query string and sent as the body of the HTTP request.

In order to use a query string in a POST request, you need to change your encoding argument to URLEncoding(destination: .queryString).

You can see more details about how Alamofire handles request parameters here.

Your code should look like:

   _url = "http://localhost:8080/"
    let parameters: Parameters = [
        "test": "123"
        ]

    Alamofire.request(_url,
                      method: .post,
                      parameters: parameters,
                      encoding: URLEncoding(destination: .queryString),
                      headers: headers)

answered Apr 07 '17 at 16:22

Pedro Castilho

10,174
2
28
39

Thank you so much to the OP and to this answer. I've been debugging my code for 3 hours straight! I've been wondering what the f went wrong!!! I always get status 500, was thinking to talk to my backend developer. Good thing I thought of passing the parameters to the URL just for testing, and then I realized that Alamofire doesn't accept parameters when encoding is JSONEnconding.default. – Glenn Posadas Jun 09 '17 at 19:27
Many thanks to you. I was struggling with this about why my post request dosen't work. Appreciate you!! – Ravi Oct 05 '18 at 15:15
In my parameters I have time in the form date string in the for "2019-08-09T05:30:00".When is passed this a parameter and used URLEncoding(destination: .queryString), my date parameter changed to 2019-08-19T05%3A30%3A00. The above method was the closest creating a right url except for the date parameter. kindly help. – user1899840 Aug 16 '19 at 10:18
Such a great answer...I am not really much familiar with alamofire & had no idea why Ino response was received from service as I was getting 400 bad request error....Thanks for great explanation as well... – jayant rawat Sep 15 '20 at 10:51

Andre · Answer 2 · 2017-04-10T15:52:48.163

29

If you want your parameters to be used in querystring, use .queryString as URLEncoding, as in: (I assume you have headers somewhere)

let _url = "http://localhost:8080/"
let parameters: Parameters = [
    "test": "123"
    ]

Alamofire.request(_url,
        method: .post,
        parameters: parameters,
        encoding: URLEncoding.queryString,
        headers: headers)

This form is suggested by Alamofire author because it's more coincise to the other, see screenshot:

See original here

edited Apr 10 '17 at 15:52

answered Apr 07 '17 at 16:25

Andre

1,135
9
20

I believe this was how it worked in Swift 2, but it was changed in Swift 3 with the addition of `JSONEncoding` and `CustomEncoding`. – Pedro Castilho Apr 07 '17 at 18:47
It's latest Alamofire version using Swift 3. Source here: https://github.com/Alamofire/Alamofire#url-encoding – Andre Apr 07 '17 at 21:09
"The Destination enumeration has three cases: ... `.queryString` - Sets or appends encoded query string result to existing query string. ..." As you can see, `.queryString` is a `Destination` value, not an `encoding` value. Encodings are of the form `URLEncoding(destination:)`, `JSONEncoding(destination:)` or other similar types. – Pedro Castilho Apr 10 '17 at 15:42
Here you can see the usage in the library example, it's URLEncoding.querystring: https://github.com/Alamofire/Alamofire/blob/144856257feadd8b409f30856a27d3b420506eb3/Tests/ParameterEncodingTests.swift – Andre Apr 10 '17 at 15:48
1

I edited my answer to add relevant information suggested by Alamofire author, I wouldn't be so sure of the down vote you assigned to me now – Andre Apr 10 '17 at 15:53

How to add Alamofire URL parameters

2 Answers2

Linked