NodeJS Express - 404/400 Responses - express

I am just wondering if 404/400 Responses in a node express app is consider an error and if it will be caught by the error handling middle ware?
I had a hard time finding this in the documentation

In HTTP/1.1, a response code of 400 or higher is considered an error.
However, Express error handling only deals with programming errors, not HTTP errors. If your app detects an error condition and sends back a 400 or 404 response, Express doesn't care (i.e. it won't call the error handler).

Related

application logs show 500 error from call Mulesoft web service

we have a application that makes a web service call to Mule ESB and the log shows mostly 500 error code during peak hours and 200 success code during off peak hours. I am not part of the Mule team, but when I talked with them they indicate that this may not be a problem on their side, they are saying nothing is received on their ends.
Now my question is if our application logs show 500 error code, won't that indicate the request has made it to the Mule ESB but was not able to process it or still possible to get 500 error code if the request is lost somewhere due to networking / router issues or similar to that?
The question is totally generic and doesn't provide any insight on the implementation. Then his answer applies to any HTTP response from any implementation and technology, be it Mule, Java Python, etc.
The answer depends on if the server is using the 500 response correctly. If they just answer 500 because it doesn't handle errors correctly then there is nothing you can imply from that.
If 500 is used correctly it is an internal error. If the issue is that they don't receive a proper response from another backend it be argued if there is not a better response code for that like 502 or 504. In any case is that team that manages the app who should troubleshoot the error.
What you can buy sure is that the request reached the application because it responded with an HTTP response.

Which is a correct HTTP status code for "Error creating resource"?

I'm developing an application with authentication, and i need to provide a appropriate status code if there is any error when registering an user, for example a database-related error.
I've been researching but i haven't found an appropriate status code.
The purpose of all HTTP errors is to communicate the operation failed. To pick the right HTTP error, you need to know why it failed.
"database-related error" sounds like a server-side bug or problem, so this is likely just a 500.

In Angular6, what is the way to simulate receiving 4xx and 5xx responses from server

I am using HttpClient’s post method to send messages to the server. To test it, I want to simulate receiving 404 and 500 responses from the server. What is the way to simulate receiving 4xx and 5xx error messages in Angular6? As far as I know, I cannot use spyOn().and.returnValue because this will not simulate server error and will not trigger the error code handler passes to the post method.

How to show the internal server errors to the user?

I am working in an API . I want to throw detailed error messages to the user. Now i am in a situation to decide what kind of error code should be sent or how to explain user if any error occurs in the application internally. For example if database connection fails , what kind of http status code i want to send to the user ?
Can anyone help ?
An HTTP status code generally refers to the status of the HTTP request itself, not the status of the application handling the request. Therefore, most server-side errors are covered by 500 Internal Server Error. Any additional info about the error should be described in the response body. For APIs, the response body will often be JSON or XML, so you can use those formats for your errors. Something like this:
HTTP/1.1 500 Internal Server Error
[headers]
{"status":"error", "message":"The request failed due to database connectivity."}
There are, however, two cases I can think of when you might want another status code. If the user has requested an API method that is not implemented, you might want a 501 Not Implemented, and when there is a temporary service outage, you can use 503 Service Unavailable.
More info about server-side status codes here.

How to get details exception from published Web Api

Is there any way to get detail exception & Stack trace from deployed Web Api?
Even if I deployed in Debug mode, do I get detail error traces?
I got bellow message from server API
"message": "Processing of the HTTP request resulted in an exception.
Please see the HTTP response returned by the 'Response' property of
this exception for details."
This happened only in server, same code running perfectly in local machine.
Did you check the content-type for the request that you are performing?
Sometimes this error comes because you don't specify this value, e.g. "application/json" in the headers of the request.
If your scenario is to have a central place to log any exceptions that happen when requests are being processed, then I would suggest to take a look at 5.1 version of Web API (released couple of days back), specifically the Global Error Handling feature.
http://www.asp.net/web-api/overview/releases/whats-new-in-aspnet-web-api-21#global-error
If you go to the above page,you should notice ExceptionLoggerContext which gives you details of the exception.
About Web API versions 5.0 and before:
In these versions there was no really a central place for catching exceptions. ExceptionFilterAttributes caught exceptions for only certain areas of Web API.