提示错误的是无法读取未定义的属性长度，就是标签长度

vue.runtime.esm.js?2b0e:619 [Vue warn]: Error in v-on handler: "TypeError: Cannot read property 'length' of undefined" found in

---> <ElButton> at packages/button/src/button.vue
       <ElFormItem> at packages/form/src/form-item.vue
         <ElForm> at packages/form/src/form.vue
           <PostArticle> at src/page/content/post-article.vue
             <RightContent> at src/layout/right-content.vue
               <ElMain> at packages/main/src/main.vue
                 <ElContainer> at packages/container/src/main.vue... (1 recursive calls)
                   <BaseView> at src/layout/base-view.vue
                     <App> at src/App.vue
                       <Root>
warn @ vue.runtime.esm.js?2b0e:619
logError @ vue.runtime.esm.js?2b0e:1884
globalHandleError @ vue.runtime.esm.js?2b0e:1879
handleError @ vue.runtime.esm.js?2b0e:1839
invokeWithErrorHandling @ vue.runtime.esm.js?2b0e:1862
invoker @ vue.runtime.esm.js?2b0e:2179
invokeWithErrorHandling @ vue.runtime.esm.js?2b0e:1854
Vue.$emit @ vue.runtime.esm.js?2b0e:3888
handleClick @ element-ui.common.js?2763:9413
invokeWithErrorHandling @ vue.runtime.esm.js?2b0e:1854
invoker @ vue.runtime.esm.js?2b0e:2179
original._wrapper @ vue.runtime.esm.js?2b0e:6917
vue.runtime.esm.js?2b0e:1888 TypeError: Cannot read property 'length' of undefined
    at VueComponent.showLabelInput (post-article.vue?b8e0:283)
    at invokeWithErrorHandling (vue.runtime.esm.js?2b0e:1854)
    at VueComponent.invoker (vue.runtime.esm.js?2b0e:2179)
    at invokeWithErrorHandling (vue.runtime.esm.js?2b0e:1854)
    at VueComponent.Vue.$emit (vue.runtime.esm.js?2b0e:3888)
    at VueComponent.handleClick (element-ui.common.js?2763:9413)
    at invokeWithErrorHandling (vue.runtime.esm.js?2b0e:1854)
    at HTMLButtonElement.invoker (vue.runtime.esm.js?2b0e:2179)
    at HTMLButtonElement.original._wrapper (vue.runtime.esm.js?2b0e:6917)
this.labels = remoteArticle.labels;
// window.console.log(this.labels);

但是我在检查之后发现是获取文章详情的问题，

getArticleDetail(articleId) {
    api.getArticleDetail(articleId).then(result => {
        if (result.code === api.success_code) {
            let remoteArticle = result.data;
            this.article.id = remoteArticle.id;
            this.article.title = remoteArticle.title;
            this.article.content = remoteArticle.content;
            this.article.categoryId = remoteArticle.categoryId;
            this.article.summary = remoteArticle.summary;
            this.article.cover = remoteArticle.cover;
            this.article.label = remoteArticle.label;
            this.article.state = remoteArticle.state;
            this.article.type = remoteArticle.type;
            this.article.createTime = remoteArticle.createTime;
            this.labels = remoteArticle.labels;
            window.console.log('labels is ==> ' +this.labels);
            //如果当前文章的状态是草稿，按钮显示发表文章
            //如果已经发布的：发布，置顶，删除，按钮显示更新
            if (this.article.state === '2') {
                this.commitText = '发表文章';
                this.disableDraftBtn = false;
            } else {
                this.commitText = '更新文章';
                //草稿这个按钮就不能用了
                this.disableDraftBtn = true;
            }
        }
    })
}

这个值是传不进去的

            this.labels = remoteArticle.labels;
            window.console.log('labels is ==> ' +this.labels);

打出log就是

labels is ==> undefined

检查数据库之后，labels是修改成功的，但是就是不显示