Meituan-Dianping/mpvue · error

The "data" option should be a function that returns a per-in

Error message

The "data" option should be a function that returns a per-instance value in component definitions.

What it means

Raised inside the data merge strategy (strats.data) when merging options without a vm — i.e. while building a component constructor via Vue.extend or global component registration. In that context childVal is present but is not a function; because a component definition is shared across instances, a static data object would be mutated by every instance simultaneously, so Vue requires the function form that returns a fresh per-instance object. The child value is effectively ignored (parentVal is kept).

Source

Thrown at src/core/util/options.js:116

        ? parentVal.call(vm)
        : undefined
      if (instanceData) {
        return mergeData(instanceData, defaultData)
      } else {
        return defaultData
      }
    }
  }
}

strats.data = function (
  parentVal: any,
  childVal: any,
  vm?: Component
): ?Function {
  if (!vm) {
    if (childVal && typeof childVal !== 'function') {
      process.env.NODE_ENV !== 'production' && warn(
        'The "data" option should be a function ' +
        'that returns a per-instance value in component ' +
        'definitions.',
        vm
      )

      return parentVal
    }
    return mergeDataOrFn.call(this, parentVal, childVal)
  }

  return mergeDataOrFn(parentVal, childVal, vm)
}

/**
 * Hooks and props are merged as arrays.
 */
function mergeHook (

View on GitHub (pinned to 6c5d78ee04)

Solutions

1. Change the component's data to a function: data() { return { ... } }
2. Ensure the data option in the component definition/SFC exports a function, not a plain object literal
3. Root instances (new Vue({...})) may keep the object form; the function requirement applies to reusable component definitions

When it happens

Trigger: Thrown at src/core/util/options.js:116 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of Meituan-Dianping/mpvue@6c5d78ee04 (2026-09-02). Data as JSON: /api/errors/e46c8f1258ff58f4. Report an issue: GitHub.