dagger/dagger · error

cannot create Boolean from %T

Error message

cannot create Boolean from %T

What it means

Boolean.DecodeInput only accepts Go bool and parseable bool strings; the default branch rejects all other types, reporting the offending type with %T. This enforces strict typing for the GraphQL Boolean scalar.

Source

Thrown at dagql/types.go:514

		Kind:        ast.Scalar,
		Name:        b.TypeName(),
		Description: "The `Boolean` scalar type represents `true` or `false`.",
		BuiltIn:     true,
	}
}

func (Boolean) DecodeInput(val any) (Input, error) {
	switch x := val.(type) {
	case bool:
		return NewBoolean(x), nil
	case string: // from default
		b, err := strconv.ParseBool(x)
		if err != nil {
			return nil, err
		}
		return NewBoolean(b), nil
	default:
		return nil, fmt.Errorf("cannot create Boolean from %T", x)
	}
}

var _ Input = Boolean(false)

func (Boolean) Decoder() InputDecoder {
	return Boolean(false)
}

func (b Boolean) ToLiteral() call.Literal {
	return call.NewLiteralBool(b.Bool())
}

func (b Boolean) Bool() bool {
	return bool(b)
}

func (b Boolean) MarshalJSON() ([]byte, error) {

View on GitHub (pinned to 82ba2681db)

Solutions

1. Pass an actual Go bool (or the strings "true"/"false" which ParseBool accepts)
2. Convert numeric flags explicitly: v != 0 before passing
3. Fix the GraphQL variable type to Boolean in the operation

Example fix

// before
flag := 1 // from config
dag.Boolean(flag) // cannot create Boolean from int
// after
dag.Boolean(flag != 0)

func isBoolDecodable(v any) bool {
    switch x := v.(type) {
    case bool:
        return true
    case string:
        _, err := strconv.ParseBool(x)
        return err == nil
    }
    return false
}

func isBoolDecodable(v any) bool {
    switch x := v.(type) {
    case bool:
        return true
    case string:
        _, err := strconv.ParseBool(x)
        return err == nil
    }
    return false
}

v, err := decode(val)
if err != nil {
    return fmt.Errorf("bad Boolean input: %w", err)
}

When it happens

Trigger: Passing nil, numbers (0/1), json.Number, or complex types as a Boolean input — e.g. a GraphQL variable typed Boolean but supplied a number or null.

Common situations: Config values stored as 0/1 ints forwarded to a Boolean argument; JSON where booleans were encoded as 0/1 numbers; SDK wrappers passing any-typed flags.

Related errors

• expected instance of %T, got %T
• cannot create Int from %T
• cannot create Float from %T
• cannot create String from %T
• merge module types into schema: %w

AI-assisted analysis of dagger/dagger@82ba2681db (2026-09-05). Data as JSON: /api/errors/280b5682074ead81. Report an issue: GitHub.