So the API I'm working with will sometimes send an error message in the response body when a request fails. This is located in response.data. Sometimes it's JSON, sometimes it's a string. I'm using the validate method so result.value is nil when an error occurs.
Is there a way of having Alamofire serialize the data from NSData to a string or for JSON to [ String : AnyObject ] like it would if the response was successful?
I would like to keep using the validate method.
EDIT:
Here's a link to a feature request I started on the Alamofire GitHub project.
https://github.com/Alamofire/Alamofire/issues/1459
There is not currently. I'm actually working on this very feature in Alamofire 4 right now. In Alamofire 3, you'll have to parse the response.data yourself if you get that validation error. In Alamofire 4, you'll at least have access to the response.data at the time of validation as well as be able to customize the Error that is generated by validation.
Most likely what the final solution will be is the ability to check in validation if you know there's going to be an error (checking response status code and headers). Then based on the type of error, you could parse the response.data to extract the error message from the server and throw a VERY SPECIFIC error from validation. This is most likely what the new system will allow. This way you could identify OAuth2 access token errors right in validation and throw your own custom error rather than having to use a convoluted system of response serializers to do it.
Swift 4
If you get an error, you can try parsing the response data as a string or as json.
import Alamofire
import SwiftyJSON
Alamofire.request("http://domain/endpoint", method: .get, parameters: nil, encoding: JSONEncoding.default, headers: nil)
.validate()
.responseJSON(completionHandler: { response in
if let error = response.error {
if let data = response.data {
if let errorString = String(bytes: data, encoding: .utf8) {
print("Error string from server: \(errorString)")
} else {
print("Error json from server: \(JSON(data))")
}
} else {
print("Error message from Alamofire: \(error.localizedDescription)")
}
}
guard let data = response.result.value else {
print("Unable to parse response data")
return
}
print("JSON from server: \(JSON(data))")
})
Related
I am using Marshmallow to validate incoming fields for a simple put request.
Now I am testing the error handling in the frontend to make sure I send the right error messages for the frontend.
I am usually sending data of type
{
password: string,
email: string
}
For now Marshmallow checks if the password is long enough and if the email is of format Email.
I collect all errors in a expect statement and send it to the frontend like this:
except ValidationError as err:
return make_response(
{"errors": err.messages}, status.HTTP_400_BAD_REQUEST
)
with Postman giving me e.g. this response:
{
"errors": {
"email": [
"Missing data for required field."
],
"password": [
"Missing data for required field."
],
}
}
All error messages are therefore collected within the field errors and sent back to the frontend.
When the error is sent back to the frontend I catch my error and all I get is this object:
Object {
"data": null,
"error": [Error: Request failed with status code 400],
}
How do I correctly send or receive the
errors: err.messages
field in the frontend within a make_response error response?
I found the solution to the problem I had here:
github.com/axios/axios/issues/960.
Apparently you have to access the response object or the error object that is send to axios. There is no interceptor needed. What I changed was this line, when resolving the promise to:
try {
resolved.data = await promise;
} catch (e) {
resolved.error = e.response.data;
}
before that I accessed the error with:
try {
resolved.data = await promise;
} catch (e) {
resolved.error = e;
}
The errors are stored within the response.data.
In the systems I am testing, there are cases that the response informs 200 (ok), but the content may indicate an error in the internal validations of the backend service. How can I read the contents of the response with Postman and schedule a successful validation if this service error code comes as expected?
You can use the tests tab in Postman to run checks on the body (JSON and XML). There are snippets which show you the syntax. You can adapt them to check for the element of the response body which indicates the error.
Postman has a tab called "Tests" where you can provide you test script for execution.
If you want to validate your request responded with 200 OK, following is the script
pm.test("Status test", function () {
pm.response.to.have.status(200);
});
If you want to validate the response contains any specified string,
pm.test("Body matches string", function () {
pm.expect(pm.response.text()).to.include("string_you_want_to_search");
});
In your case am assuming the above script can be used. In case the response body is JSON,
pm.test("JSON Body match", function () {
var respBody = pm.response.json();
pm.expect(respBody.<json node>).is.to.equal("Error_name");
});
Example JSON response body
{
"id" : 100,
"status" : "Bad Request"
}
pm.test("JSON Body matches string", function () {
var respBody = pm.response.json();
pm.expect(respBody.status).is.to.equal("Bad Request");
});
I am making a request from the front-end to a route in my backend that is validating the token associated with a user, which would send an error response back to the front-end if the token has expired. I am sending some json with it but upon doing console.log of the error message in the catch block, the json sent along the error response is not shown.
Sending the error response like this
res.status(401).json({
message: 'User session has expired'
})
But the response that I am getting in the catch block in the front-end has no sign of the json sent with the error.
POST http://localhost:3001/check-validation 401 (Unauthorized)
Error: Request failed with status code 401
at createError (createError.js:17)
at settle (settle.js:19)
at XMLHttpRequest.handleLoad (xhr.js:78)
I don't understand why the json sent along the error response is not shown and how to get it?
Upon doing console.log of the error only the stacktrace of the error is shown and not the data associated with it. The data sent with it can be procured and depends on how the request has been made or by what library it has been made. If the request is made by axios then the following can be done:
axios.post('/formulas/create', {
name: "",
parts: ""
})
.then(response => {
console.log(response)
})
.catch(error => {
console.log(error.response.data.message)
});
Here, in axios the details of the error would be wrapped up in error.response. Whereas, if the request was made by the fetch API then something following can resolve the problem:
fetch('/401').then(function(response) {
if (response.status === 401) {
return response.json()
}
}).then(function(object) {
console.log(object.message)
})
P.S I was searching a lot regarding this problem but didn't get an answer on SO, neither got any article or docs regarding it, even the official Express docs on error handling were not helpful. At last, I understood that the problem lies with the library that is being used to make the request. That's why answering my own question to mark the presence of this question on SO. A detailed discussion can be found here related to axios and here related to fetch api
I'm building my own WebhookClient for dialog flow. My code is the following (using Azure Functions, similar to Firebase Functions):
module.exports = async function(context, req) {
const agent = new WebhookClient({ request: context.req, response: context.res });
function welcome(agent) {
agent.add(`Welcome to my agent!!`);
}
let intentMap = new Map();
intentMap.set("Look up person", welcome);
agent.handleRequest(intentMap);
}
I tested the query and the response payload looks like this:
{
"fulfillmentText": "Welcome to my agent!!",
"outputContexts": []
}
And the headers in the response look like this:
Transfer-Encoding: chunked
Content-Type: application/json; charset=utf-8
Server: Microsoft-IIS/10.0
X-Powered-By: ASP.NET
Date: Tue, 11 Dec 2018 18:16:06 GMT
But when I test my bot in dialog flow, it returns the following:
Webhook call failed. Error: Failed to parse webhook JSON response:
Expect message object but got:
"笀ഀ ∀昀甀氀昀椀氀氀洀攀渀琀吀攀砀琀∀㨀 ∀圀攀氀挀漀洀攀 琀漀 洀礀 愀最攀渀琀℀℀∀Ⰰഀ ∀漀甀琀瀀甀琀䌀漀渀琀攀砀琀猀∀㨀 嬀崀ഀ紀".
There's Chinese symbols!? Here's a video of me testing it out in DialogFlow: https://imgur.com/yzcj0Kw
I know this should be a comment (as it isn't really an answer), but it's fairly verbose and I didn't want it to get lost in the noise.
I have the same problem using WebAPI on a local machine (using ngrok to tunnel back to Kestrel). A friend of mine has working code (he's hosting in AWS rather than Azure), so I started examining the differences between our responses. I've notice the following:
This occurs with Azure Functions and WebAPI (so it's not that)
The JSON payloads are identical (so it's not that)
Working payload isn't chunked
Working payload doesn't have a content type
As an experiment, I added this code to Startup.cs, in the Configure method:
app.Use(async (context, next) =>
{
var original = context.Response.Body;
var memory = new MemoryStream();
context.Response.Body = memory;
await next();
memory.Seek(0, SeekOrigin.Begin);
if (!context.Response.Headers.ContentLength.HasValue)
{
context.Response.Headers.ContentLength = memory.Length;
context.Response.ContentType = null;
}
await memory.CopyToAsync(original);
});
This code disables response chunking, which is now causing a new and slightly more interesting error for me in the google console:
*Webhook call failed. Error: Failed to parse webhook JSON response: com.google.gson.stream.MalformedJsonException: Unterminated object at line 1 column 94 path $.\u0000\\"\u0000f\u0000u\u0000l\u0000f\u0000i\u0000l\u0000l\u0000m\u0000e\u0000n\u0000t\u0000M\u0000e\u0000s\u0000s\u0000a\u0000g\u0000e\u0000s\u0000\\"\u0000.\
I thought this could be encoding at first, so I stashed my JSON as a string and used the various Encoding classes to convert between them, to no avail.
I fired up Postman and called my endpoint (using the same payload as Google) and I can see the whole response payload correctly - it's almost as if Google's end is terminating the stream part-way through reading...
Hopefully, this additional information will help us figure out what's going on!
Update
After some more digging and various server/lambda configs, I spotted this post here: https://github.com/googleapis/google-cloud-dotnet/issues/2258
It turns out that json.net IS the culprit! I guess it's something to do with the formatters on the way out of the pipeline. In order to prove this, I added this hard-coded response to my POST controller and it worked! :)
return new ContentResult()
{
Content = "{\"fulfillmentText\": null,\"fulfillmentMessages\": [],\"source\": null,\"payload\": {\"google\": {\"expectUserResponse\": false,\"userStorage\": null,\"richResponse\": {\"items\": [{\"simpleResponse\": {\"textToSpeech\": \"Why hello there\",\"ssml\": null,\"displayText\": \"Why hello there\"}}],\"suggestions\": null,\"linkOutSuggestion\": null}}}}",
ContentType = "application/json",
StatusCode = 200
};
Despite the HTTP header saying the charset is utf-8, that is definitely using the utf-16le character set, and then the receiving side is treating them as utf-16be. Given you're running on Azure, it sounds like there is some configuration you need to make in Azure Functions to represent the output as UTF-8 instead of using UTF-16 strings.
I have an issue with AFNetworking and AFJSONRequestSerializer. I try to access an API, and the request contains a text/plain header. Here's my code :
class BaseService {
var manager: AFHTTPRequestOperationManager!
init() {
manager = AFHTTPRequestOperationManager()
manager.responseSerializer = AFJSONResponseSerializer()
manager.requestSerializer = AFJSONRequestSerializer(writingOptions: NSJSONWritingOptions.allZeros)
}
}
class UserService: BaseService {
func startNewEntry(name: String) {
let params = [
"time_entry": [
"description": name,
"created_with": "fooBar"
]
]
manager.POST(
"endpoint",
parameters: params,
success: { (operation, response) -> Void in
let json = JSON(response)
println("OK")
println(json)
Context.shared.entries.getFromJSON(json)
}) { (operation, error) -> Void in
println("-- ERROR --")
println(operation)
println(error)
}
}
Do you know this issue ?
No, this code will create a request with a content type of application/json. But I wonder if you perhaps mislead by an error message that said:
Request failed: unacceptable content-type: text/html
If you got that, that's not telling you that that the request had an unacceptable content type, but rather that the request failed because the response was text/html. And this is a very common issue: If server code that is attempting to create a JSON response fails for some reason, sometimes the error message isn't JSON, but rather it's HTML.
I would suggest adding the following inside the failure block of your POST method in order to see what this text/html response was:
if operation.responseData != nil {
println(NSString(data: operation.responseData, encoding: NSUTF8StringEncoding))
}
This way, if you get a text error message from the server (e.g. the request was malformed or what have you), you'll be able to read the HTML response you got back.