Element-ui上传图片按顺序展示

背景

不知道你上传图片的时候有没有过这样的情况，批量上传多张图片，可能因为图片大小或者网络问题，导致图片返回的顺序和上传时的顺序不一样。因为我们公司是做电商的，即使我们的支持拖动排序，运营还是希望图片能够严格的按照他们上传的顺序展示。

解决问题

在上传组件的on-success的方法中，有3个参数 response, file, fileList 其中fileList就是之前上传成功图片的集合，且upload组件提供了clearFiles方法，用来清空fileList，每次上传成功，我们调用clearFiles方法就行了

上代码

<template>
  <!-- 上传单张图片 -->
  <div v-if="!multiple" class="image-item">
    <div class="image-wrap" v-if="imgUrl">
      <img :src="imgUrl" :style="imgStyle" />
      <div class="icon-wrap" @click.stop="removeFile">
        <i class="el-icon-delete"></i>
      </div>
    </div>
    <el-upload
      v-else
      ref="imageUpload"
      action="//up.qbox.me"
      :before-upload="beforeUpload"
      :on-success="handleSuccess"
      class="image-uploader"
      :on-error="onError"
      :data="form"
      :show-file-list="false"
      :disabled="loading"
      accept="image/*">
      <i :class="loading ? 'el-icon-loading' : 'el-icon-plus'" :style="imgStyle"></i>
    </el-upload>
  </div>
  <!-- 上传多张图片 -->
  <div class="image-list" v-else>
    <draggable v-model="showImgList" :options="{group:'image'}" @change="dragChange">
      <div v-for="(image, index) in showImgList" :key="index" class="image-wrap">
        <img :src="imgUrl" :style="imgStyle" />
        <div class="icon-wrap" @click.stop="removeFile(index)">
          <i class="el-icon-delete"></i>
        </div>
      </div>
      <el-upload
        ref="imageListUpload"
        action="//up.qbox.me"
        :before-upload="beforeUpload"
        :on-success="handleSuccess"
        class="image-uploader"
        :on-error="onError"
        :data="form"
        multiple
        :disabled="loading"
        :show-file-list="false"
        accept="image/*">
        <i :class="loading ? 'el-icon-loading' : 'el-icon-plus'" :style="imgStyle"></i>
      </el-upload>
    </draggable>
  </div>
</template>
<script type="text/babel">
/**
 * 上传图片或文件
 */
import md5 from 'blueimp-md5'
import draggable from 'vuedraggable'

export default {
  props: {
    // 接收和返回的数据
    data: {
      type: [Array, String, Object],
      default: () => {
        return ''
      }
    },
    // 上传多个文件时，文件限制的个数
    limit: {
      type: Number,
      default: () => {
        return 100
      }
    },
    // 一次上传多个
    multiple: {
      type: Boolean,
      default: false,
    },
    //图片展示的宽度
    imgWidth: {
      type: Number,
      default: 150,
    },
    imgHeight: {
      type: Number,
      default: 150,
    },
    //期望上传图片的宽度
    rule: [ Object, Function ]
  },
  data() {
    return {
      imgUrl: '',
      imageCdn: '', //图片的cdn
      form: {
        token: '', //七牛上传的token
      },
      showImgList: [],
      fileList: [],
      clipboard: false,
      isDrag: false,
      handleSuccess: null,
      loading: false,
    }
  },
  components: { draggable },
  watch: {
    data: {
      handler(value) {
        if (!this.multiple) {
          this.imgUrl = value
        } else if (this.multiple) {
          this.showImgList = value
        }
      },
      immediate: true
    }
  },
  computed: {
    imgStyle() {
      return {
         this.imgWidth + 'px', 
        height: this.imgHeight + 'px',
        lineHeight: this.imgHeight + 'px',
      }
    }
  },
  mounted() {
    //防抖
    this.handleSuccess = _.debounce(this.uploadSuccess, 500)
  },
  methods: {
    beforeUpload(file) {
      if (file.type.split('/')[0] === 'image') {
        let tempSize = file.size / 5242880
        if (tempSize > 1) {
          this.$message.error('图片尺寸不得大于5M！')
          return false
        }
      }
      this.loading = true
      let tempNames = file.name.split('.')
      let fileType = tempNames[tempNames.length - 1]
      let curr = (+new Date()).toString()
      let random = Math.random() * 10000
      let md5Str = md5(`${curr}${random}${file.name}`)
      this.form.key = `ai-admin/${md5Str}.${fileType}`
    },
    async uploadSuccess(response, file, fileList) {
      try {
        for (let fileInfo of fileList) {
          let imageInfo = await this.getImageInfo(fileInfo.response.key)
          if (this.rule) {
            this.rule(imageInfo, (error) => {
              if (error) {
                throw(error)
              }
            })
          }
          if (imageInfo.width > 2048 || imageInfo.height > 2048) {
            throw(new Error('图片长或者宽不能超过2048'))
          } else {
            if (this.type === 'image') {
              this.imgUrl = response.key
              this.$emit('update:data', response.key)
            } else {
              if (this.showImgList.length >= this.limit) { // 限制图片张数
                this.showImgList.length = this.limit
                throw(new Error(`最多上传 ${this.limit} 张图片`))
              }
              this.showImgList.push(imageInfo)
              this.$emit('update:data', this.showImgList)
            }
          }
        }
      } catch (error) {
        this.$message.error(error.message)
      } finally {
        this.loading = false
        this.$refs.imageListUpload && this.$refs.imageListUpload.clearFiles()
        this.$refs.imageUpload && this.$refs.imageUpload.clearFiles()
      }
    },
    removeFile(index) {
      this.$confirm('确定删除该图片吗?', '提示', {
        confirmButtonText: '确定',
        cancelButtonText: '取消',
        type: 'warning'
      }).then(() => {
        if (this.type === 'image') {
          this.$emit('update:data', typeof this.data === 'object' ? {} : '')
        } else {
          this.showImgList.splice(index, 1)
          this.$emit('update:data', this.showImgList)
        }
      })
    },
    onError() {
      this.$message.error('上传文件失败')
    },
    getImageInfo(url){
      return new Promise((resolve, reject)=>{
        let image = new Image()
        image.src = `${this.imageCdn}${url}`
        image.onload = () => {
          resolve({
            image: url,
             image.width,
            height: image.height
          })
        }
        image.onerror = () => {
          reject(new Error('Could not load image at ' + url));
        };
      })
    },
    dragChange() {
      this.$emit('update:data', this.showImgList)
    },
    handleRemove(file, fileList) {
      let imgList = fileList.map(item => {
        return item.response.key
      })
      this.$emit('update:data', imgList)
    },
    handlerClipboard(event) {
      if (this.clipboard) {
        const rawFile = getImageFromClipboard(event)
        if (rawFile) {
          this.$refs.elUpload.handleStart(rawFile)
          this.$refs.elUpload.$refs['upload-inner'].upload(rawFile)
        }
      }
    },
  }
}
</script>
<style lang="less" scoped>
.image-list, .image-item {
  display: flex;
  .image-wrap {
    position: relative;
    display: inline-block;
    box-sizing: content-box;
    margin: 0 8px 8px 0;
    vertical-align: top;
    &:hover {
      .icon-wrap {
        opacity: 1;
      }
    }
    .icon-wrap {
      position: absolute;
      left: 0;
      bottom: 0;
      width: 100%;
      height: 30px;
      cursor: default;
      text-align: center;
      color: #fff;
      opacity: 0;
      font-size: 20px;
      background-color: rgba(0, 0, 0, .7);
      transition: opacity .3s;
      .el-icon-zoom-in {
        cursor: pointer;
        margin-right: 8px;
      }
      .el-icon-delete {
        cursor: pointer;
      }
    }
  }
}
.image-item {
  display: inline-flex;
}
/deep/.image-uploader {
  display: inline-block;
  .el-upload {
    border: 1px dashed #d9d9d9;
    border-radius: 6px;
    cursor: pointer;
    position: relative;
    overflow: hidden;
    [class^="el-icon"] {
      font-size: 28px;
      color: #8c939d;
      text-align: center;
    }
    &:hover {
      border-color: #409EFF;
    }
  }
}
</style>

注意

这是我封装的上传图片的组件，支持 类v-model的传参方式，上传多张图时支持拖动，写图片规则（例如宽高是多少），删除图片

特别注意：因为我们还封装了图片组件，在这里被我替换了，所以图片展示有上面的代码可能有点问题，稍微改下就行

用法（只允许上传正方形的图）

<template>
  <image-upload :data.sync="image" :rule="rule"></image-upload>
</template>
<script>
export default {
  data(){
    let validate = ({ width, height }, callback) => {
      if (width === height) {
        callback()
      } else {
        callback(new Error('请上传正方形的图'))
      }
    }
    return {
      rule: validate,
      image: ''
    }
  },
}
</script>

效果