Description

Document handling of null values in HTTP file variables

User feedback transferred from UUF System:

"How to deal with null values when setting a variable? The script execution is completely halted, while null is a perfect valid value for e.g. JSON. Using the ($var || 0) syntax for a fall-back value also does not work."

The following Problem/Solution is just an AI generated recommendation and should be treated as such:

Problem Statement

The current documentation for .http files in Visual Studio 2022 does not address how to handle null values in variables. This is a common use case when working with APIs that may return null values in JSON responses or when users need to explicitly send null values in request payloads. The feedback indicates that variable execution is halted when null values are encountered, and common JavaScript-like fallback patterns (($var || 0)) do not work.

Proposed Solution

Add a new section under the "Variables" section of the documentation that specifically addresses how to handle null values in .http file variables, including:

1. How to explicitly set a variable to null
2. How to handle null values in responses
3. Recommended patterns for fallback values when a variable might be null

Suggested Changes

Add the following content after line 188 (after the Variables section) in the aspnetcore/test/http-files.md file:

### Handling null values

When working with variables in `.http` files, you might need to handle `null` values in requests or responses. Here's how to work with null values:

#### Setting a variable to null
To explicitly set a variable to `null` in your request body:

```http
@nullValue=null

POST https://api.example.com/data
Content-Type: application/json

{
  "propertyWithNull": {{nullValue}}
}

### Page URL

https://learn.microsoft.com/en-us/aspnet/core/test/http-files?view=aspnetcore-9.0

### Content source URL

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/test/http-files.md

### Document ID

26f1374f-556a-35fc-cc42-b8911746db80

### Platform Id

816aec78-770f-4b7d-c919-4cdece185115

### Article author

@tdykstra

### Metadata

* ID: 26f1374f-556a-35fc-cc42-b8911746db80
* PlatformId: 816aec78-770f-4b7d-c919-4cdece185115 
* Service: **aspnet-core**
* Sub-service: **testing**

[Related Issues](https://github.com/dotnet/AspNetCore.Docs/issues?q=is%3Aissue+is%3Aopen+26f1374f-556a-35fc-cc42-b8911746db80)