binder: DisableStructDynamicBindings setting is set to true:

Error message

binder: DisableStructDynamicBindings setting is set to true: dynamic binding found: %s

What it means

When Container.DisableStructDynamicBindings is true, every field binding of a registered struct must be static (resolved once at setup). A field whose dependency is dynamic (resolved per request) is rejected with this panic, keeping the struct a singleton.

Source

Thrown at hero/struct.go:101

	// fmt.Printf("Service: %s, Bindings(%d):\n", typ, len(bindings))
	for _, b := range bindings {
		// fmt.Printf("* " + b.String() + "\n")
		if b.Dependency.Static {
			// Fill now.
			input, err := b.Dependency.Handle(nil, b.Input)
			if err != nil {
				if err == ErrSeeOther {
					continue
				}

				panic(err)
			}

			elem.FieldByIndex(b.Input.StructFieldIndex).Set(input)
		} else if !b.Dependency.Static {
			if disableStructDynamicBindings {
				panic(fmt.Sprintf("binder: DisableStructDynamicBindings setting is set to true: dynamic binding found: %s", b.String()))
			}

			singleton = false
		}
	}

	if isSingleton && !singleton {
		panic(fmt.Sprintf("binder: Singleton setting is set to true but struct has dynamic bindings: %s", typ))
	}

	s := &Struct{
		ptrValue:    v,
		ptrType:     typ,
		elementType: elem.Type(),
		bindings:    bindings,
		Singleton:   singleton,
	}

View on GitHub (pinned to 7bedaf55a0)

Solutions

Remove or change the dynamic field to a static dependency type (a service/config registered at startup).
Set c.DisableStructDynamicBindings = false if dynamic per-request fields are intended (struct stops being a singleton).
Split the struct: keep static fields in the singleton struct and move request-scoped data into handler parameters.
Inspect b.Dependency.Static for each field binding to identify which one is dynamic.

Example fix

// before
c.DisableStructDynamicBindings = true
c.Struct(&Controller{ /* has field Payload *UserRequest -> dynamic */ })
// after
c.Struct(&Controller{ Svc *UserService }) // only static fields
// and handle request payloads via handler method parameters instead

Defensive patterns

Strategy: validation

Validate before calling

// Before enabling DisableStructDynamicBindings, audit struct fields:
for each field binding b of target struct {
	if !b.Dependency.Static { panic("dynamic field: " + b.String()) }
}
c.DisableStructDynamicBindings = true

Prevention

Only enable DisableStructDynamicBindings when all controller fields are static services/config.
Keep request-scoped inputs in handler method parameters, not struct fields.
Split mixed structs into a static singleton plus per-request handler inputs.

When it happens

Trigger: Registering a struct with c.Struct where one field's type resolves to a per-request dependency (e.g. request payload, path parameter) while DisableStructDynamicBindings = true.

Common situations: Enabling the optimization setting globally but one controller struct still has a dynamic field (e.g. a request body input); adding a new request-scoped field to an existing singleton controller after enabling the setting.

Related errors

AI-assisted analysis of kataras/iris@7bedaf55a0 (2026-08-30). Data as JSON: /api/errors/da80b967ab2e6fb8. Report an issue: GitHub.