vue-element下拉选择框，选中时value值改变

<el-form-item :label="$t('类别')" prop="category">
      <el-select placeholder="请选择类别" v-model="data.category_id">
        <template v-for="item in data.category">
          <el-option :label="item.category_name" :data-id="item.id" v-bind:value="item.id"></el-option>
        </template>
      </el-select>
    </el-form-item>

data结构：

data{

        category_id:3,

        category:{

[id:1,category_name:类别1],

[id:2,category_name:类别2

        }

}

效果：