AL0021 - Multiple structured form sources

An endpoint can only have one structured form source

Source: AL0020ToAL0024FormBindingAnalyzer.cs

Description

An endpoint can only have one structured form source. Multiple [FromForm] DTOs or IFormCollections create ambiguity about which parameter receives the form data.

Bad Code

([FromForm] UserDto user, [FromForm] AddressDto address)

Good Code

([FromForm] CombinedDto data) // combine into single DTO

Properties

• Category: ASP.NET Core
• Severity: Error
• Enabled by default: True
• Code fix available: False

Configuration

dotnet_diagnostic.AL0021.severity = warning