Call Python from the interface

Use the starter add-on's binding location

This guide builds on Starter tutorial. Python has imported bpy and _get_plugin binds on demand. The example adds a read-only action that looks up object type by name without changing the scene. Replace my_addon with your actual identity on both sides.

Define the handler in the module

def _inspect_object(payload, context):
    name = payload.get("name") if isinstance(payload, dict) else None
    if not isinstance(name, str) or not name.strip():
        return {"ok": False, "message": "请输入对象名称。"}
    obj = bpy.context.scene.objects.get(name)
    if obj is None:
        return {"ok": False, "message": "当前场景没有这个对象。"}
    return {"ok": True, "name": obj.name, "type": obj.type}

Register once after bind succeeds in _get_plugin. Do not register on every page click or overwrite existing actions.

_plugin.bridge().action("plugin.my_addon.inspect_object", _inspect_object)

Send requests and show results from the button

Add these controls to the existing page shell and save JavaScript as inspect.js beside it. Keep the existing close and drag scripts.

<label>Object name <input id="object-name" type="text"></label>
<button id="inspect" type="button">Read object</button>
<p id="inspect-result" role="status"></p>
<script src="inspect.js"></script>

const button = document.getElementById("inspect");
const input = document.getElementById("object-name");
const output = document.getElementById("inspect-result");
button.addEventListener("click", async () => {
  button.disabled = true;
  try {
    const result = await window.acquireNexusWebUI().action.call(
      "plugin.my_addon.inspect_object", { name: input.value }
    );
    output.textContent = result.ok
      ? `${result.name}：${result.type}` : result.message;
  } catch (error) {
    output.textContent = `读取失败：${error.message || String(error)}`;
  } finally {
    button.disabled = false;
  }
});

The add-on validates arguments and execution conditions

context supplies origin, user-initiation information, and window identity; it is not bpy.context. Before changing a scene, check mode, target existence, and application permissions/selection. Do not trust page-provided names, values, or success flags as facts.

Return only JSON-compatible data. Explain application failures; do not swallow unexpected exceptions or fabricate success. Catch page-side rejections and re-enable the button.

Connect modifying actions to state refresh

If an action changes published state, declare invalidates=('plugin.my_addon.objects',) when registering, or manually invalidate at the actual change notification. Declare that state with your own field schema first. See Keep the interface in sync with data.

This read-only action needs neither refresh nor undo. For undoable transforms, see Value dragging and undo. Ordinary actions are not automatic undo transactions.

Verify three inputs

• An existing scene object name displays its actual name and type.
• A missing or blank name explains the issue and leaves the button reusable.
• A temporarily mismatched action name should display a call failure. Restore the correct name before delivery.

Include the script in the packaging manifest. An ordinary browser has no Blender bridge and cannot verify this read.