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SWGQL01: Static extension method validation

Overview​

Rule ID: SWGQL01
Category: GraphQL
Severity: Error
Status: Enabled by default

Description​

This rule enforces that field extension methods with the [Parent] parameter on non-static classes must be instance methods, not static methods. This is a GraphQL-specific rule for HotChocolate resolvers.

When This Rule Triggers​

The analyzer reports a diagnostic when:

  • A method has a parameter decorated with [Parent] attribute
  • The method is declared as static
  • The containing class is not static

Why This Matters​

GraphQL Field Resolution Context​

In HotChocolate, field extension methods use the [Parent] attribute to indicate that the parameter represents the parent object being resolved. These methods must:

  • Be instance methods if the class is not static (to have access to instance state)
  • Be static methods only if the containing class itself is static

Violating this creates runtime errors or unexpected behavior during GraphQL query execution.

How to Fix​

Option 1: Make the method an instance method (if class is not static)​

public class UserExtensions
{
    // ❌ WRONG - static method in non-static class with [Parent]
    public static string GetFullName([Parent] User user)
    {
        return $"{user.FirstName} {user.LastName}";
    }
}

// ✅ CORRECT - instance method
public class UserExtensions
{
    public string GetFullName([Parent] User user)
    {
        return $"{user.FirstName} {user.LastName}";
    }
}

Option 2: Make the class static (if you want static methods)​

// ✅ CORRECT - static class with static method
public static class UserExtensions
{
    public static string GetFullName([Parent] User user)
    {
        return $"{user.FirstName} {user.LastName}";
    }
}

Configuration​

This rule is enabled by default as an error. To change its severity:

[*.cs]
dotnet_diagnostic.SWGQL01.severity = warning

To disable it:

[*.cs]
dotnet_diagnostic.SWGQL01.severity = none

See Also​