Element-UI中Upload上傳檔案前端快取處理
Element-UI對於檔案上傳元件的功能點著重於檔案傳遞到後臺處理,所以要求action為必填屬性。
但是如果需要讀取本地檔案並在前端直接處理,檔案就沒有必要傳遞到後臺,比如在本地開啟一個JSON檔案,利用JSON檔案在前端進行動態展示等等。
下面就展示一下具體做法:
首先定義一個jsonContent, 我們的目標是將本地選取的檔案轉換為JSON賦值給jsonContent
然後我們的模板檔案是利用el-dialog和el-upload兩個元件組合:這裡停止檔案自動上傳模式:auto-upload="false"
<el-button type="primary" @click="dialogVisible = true">Load from File</el-button> <el-dialog title="Load JSON document from file" :visible.sync="dialogVisible"> <el-upload :file-list="uploadFiles" action="alert" :auto-upload="false" multiple :on-change="loadJsonFromFile"> <el-button size="small" type="primary">Select a file</el-button> <div slot="tip">upload only jpg/png files, and less than 500kb</div> </el-upload> <span slot="footer"> <el-button type="primary" @click="dialogVisible = false">cancel</el-button> <el-button type="primary" @click="loadJsonFromFileConfirmed">confirm</el-button> </span> </el-dialog>
最後通過html5的filereader對變數uploadFiles中的檔案進行讀取並賦值給jsonContent
if (this.uploadFiles) { for (let i = 0; i < this.uploadFiles.length; i++) { let file = this.uploadFiles[i] console.log(file.raw) if (!file) continue let reader = new FileReader() reader.onload = async (e) => { try { let document = JSON.parse(e.target.result) console.log(document) } catch (err) { console.log(`load JSON document from file error: ${err.message}`) this.showSnackbar(`Load JSON document from file error: ${err.message}`, 4000) } } reader.readAsText(file.raw) } }
為方便測試,以下是完整程式碼:
<template> <div> <el-button type="primary" @click="dialogVisible = true">Load from File</el-button> <el-dialog title="Load JSON document from file" :visible.sync="dialogVisible"> <el-upload :file-list="uploadFiles" action="alert" :auto-upload="false" multiple :on-change="loadJsonFromFile"> <el-button size="small" type="primary">Select a file</el-button> <div slot="tip">upload only jpg/png files, and less than 500kb</div> </el-upload> <span slot="footer"> <el-button type="primary" @click="dialogVisible = false">cancel</el-button> <el-button type="primary" @click="loadJsonFromFileConfirmed">confirm</el-button> </span> </el-dialog> </div> </template> <script> export default { data () { return { // data for upload files uploadFilename: null, uploadFiles: [], dialogVisible: false } }, methods: { loadJsonFromFile (file, fileList) { this.uploadFilename = file.name this.uploadFiles = fileList }, loadJsonFromFileConfirmed () { console.log(this.uploadFiles) if (this.uploadFiles) { for (let i = 0; i < this.uploadFiles.length; i++) { let file = this.uploadFiles[i] console.log(file.raw) if (!file) continue let reader = new FileReader() reader.onload = async (e) => { try { let document = JSON.parse(e.target.result) console.log(document) } catch (err) { console.log(`load JSON document from file error: ${err.message}`) this.showSnackbar(`Load JSON document from file error: ${err.message}`, 4000) } } reader.readAsText(file.raw) } } this.dialogVisible = false } } } </script>
作者:java_augur
來源:CSDN
原文:https://blog.csdn.net/java_au...
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