我正在使用 Vue.js 计算属性，但遇到了一个问题:计算方法 IS 在正确的时间被调用，但计算方法返回的值被忽略了!
我的方法
computed: {
filteredClasses() {
let classes = this.project.classes
const ret = classes && classes.map(klass => {
const klassRet = Object.assign({}, klass)
klassRet.methods = klass.methods.filter(meth => this.isFiltered(meth, klass))
return klassRet
})
console.log(JSON.stringify(ret))
return ret
}
}
console.log 语句打印出的值是正确的，但是当我在模板中使用 filteredClasses 时，它只使用第一个缓存值 并且从不更新模板。 Vue chrome devtools 证实了这一点(filteredClasses 在初始缓存后永远不会改变)。
谁能告诉我一些信息，说明为什么会这样？
项目.vue
<template>
<div>
<div class="card light-blue white-text">
<div class="card-content row">
<div class="col s4 input-field-white inline">
<input type="text" v-model="filter.name" id="filter-name">
<label for="filter-name">Name</label>
</div>
<div class="col s2 input-field-white inline">
<input type="text" v-model="filter.status" id="filter-status">
<label for="filter-status">Status (PASS or FAIL)</label>
</div>
<div class="col s2 input-field-white inline">
<input type="text" v-model="filter.apkVersion" id="filter-apkVersion">
<label for="filter-apkVersion">APK Version</label>
</div>
<div class="col s4 input-field-white inline">
<input type="text" v-model="filter.executionStatus" id="filter-executionStatus">
<label for="filter-executionStatus">Execution Status (RUNNING, QUEUED, or IDLE)</label>
</div>
</div>
</div>
<div v-for="(klass, classIndex) in filteredClasses">
<ClassView :klass-raw="klass"/>
</div>
</div>
</template>
<script>
import ClassView from "./ClassView.vue"
export default {
name: "ProjectView",
props: {
projectId: {
type: String,
default() {
return this.$route.params.id
}
}
},
data() {
return {
project: {},
filter: {
name: "",
status: "",
apkVersion: "",
executionStatus: ""
}
}
},
async created() {
// Get initial data
const res = await this.$lokka.query(`{
project(id: "${this.projectId}") {
name
classes {
name
methods {
id
name
reports
executionStatus
}
}
}
}`)
// Augment this data with latestReport and expanded
const reportPromises = []
const reportMeta = []
for(let i = 0; i < res.project.classes.length; ++i) {
const klass = res.project.classes[i];
for(let j = 0; j < klass.methods.length; ++j) {
res.project.classes[i].methods[j].expanded = false
const meth = klass.methods[j]
if(meth.reports && meth.reports.length) {
reportPromises.push(
this.$lokka.query(`{
report(id: "${meth.reports[meth.reports.length-1]}") {
id
status
apkVersion
steps {
status platform message time
}
}
}`)
.then(res => res.report)
)
reportMeta.push({
classIndex: i,
methodIndex: j
})
}
}
}
// Send all report requests in parallel
const reports = await Promise.all(reportPromises)
for(let i = 0; i < reports.length; ++i) {
const {classIndex, methodIndex} = reportMeta[i]
res.project.classes[classIndex]
.methods[methodIndex]
.latestReport = reports[i]
}
this.project = res.project
// Establish WebSocket connection and set up event handlers
this.registerExecutorSocket()
},
computed: {
filteredClasses() {
let classes = this.project.classes
const ret = classes && classes.map(klass => {
const klassRet = Object.assign({}, klass)
klassRet.methods = klass.methods.filter(meth => this.isFiltered(meth, klass))
return klassRet
})
console.log(JSON.stringify(ret))
return ret
}
},
methods: {
isFiltered(method, klass) {
const nameFilter = this.testFilter(
this.filter.name,
klass.name + "." + method.name
)
const statusFilter = this.testFilter(
this.filter.status,
method.latestReport && method.latestReport.status
)
const apkVersionFilter = this.testFilter(
this.filter.apkVersion,
method.latestReport && method.latestReport.apkVersion
)
const executionStatusFilter = this.testFilter(
this.filter.executionStatus,
method.executionStatus
)
return nameFilter && statusFilter && apkVersionFilter && executionStatusFilter
},
testFilter(filter, item) {
item = item || ""
let outerRet = !filter ||
// Split on '&' operator
filter.toLowerCase().split("&").map(x => x.trim()).map(seg =>
// Split on '|' operator
seg.split("|").map(x => x.trim()).map(segment => {
let quoted = false, postOp = x => x
// Check for negation
if(segment.indexOf("!") === 0) {
if(segment.length > 1) {
segment = segment.slice(1, segment.length)
postOp = x => !x
}
}
// Check for quoted
if(segment.indexOf("'") === 0 || segment.indexOf("\"") === 0) {
if(segment[segment.length-1] === segment[0]) {
segment = segment.slice(1, segment.length-1)
quoted = true
}
}
if(!quoted || segment !== "") {
//console.log(`Item: ${item}, Segment: ${segment}`)
//console.log(`Result: ${item.toLowerCase().includes(segment)}`)
//console.log(`Result': ${postOp(item.toLowerCase().includes(segment))}`)
}
let innerRet = quoted && segment === "" ?
postOp(!item) :
postOp(item.toLowerCase().includes(segment))
//console.log(`InnerRet(${filter}, ${item}): ${innerRet}`)
return innerRet
}).reduce((x, y) => x || y, false)
).reduce((x, y) => x && y, true)
//console.log(`OuterRet(${filter}, ${item}): ${outerRet}`)
return outerRet
},
execute(methID, klassI, methI) {
this.project.classes[klassI].methods[methI].executionStatus = "QUEUED"
// Make HTTP request to execute method
this.$http.post("/api/Method/" + methID + "/Execute")
.then(response => {
}, error =>
console.log("Couldn't execute Test: " + JSON.stringify(error))
)
},
registerExecutorSocket() {
const socket = new WebSocket("ws://localhost:4567/api/Executor/")
socket.onmessage = msg => {
const {methodID, report, executionStatus} = JSON.parse(msg.data)
for(let i = 0; i < this.project.classes.length; ++i) {
const klass = this.project.classes[i]
for(let j = 0; j < klass.methods.length; ++j) {
const meth = klass.methods[j]
if(meth.id === methodID) {
if(report)
this.project.classes[i].methods[j].latestReport = report
if(executionStatus)
this.project.classes[i].methods[j].executionStatus = executionStatus
return
}
}
}
}
},
prettyName: function(name) {
const split = name.split(".")
return split[split.length-1]
}
},
components: {
"ClassView": ClassView
}
}
</script>
<style scoped>
</style>
最佳答案
如果您打算在 project.classes.someSubProperty 更改时更新计算属性，则在定义计算属性时该子属性必须存在。 Vue 无法检测属性的添加或删除，只能检测对现有属性的更改。
当使用带有空 state 对象的 Vuex 存储时，这让我很困扰。我对状态的后续更改不会导致依赖于它被重新评估的计算属性。向 Veux 状态添加具有空值的显式键解决了这个问题。
我不确定显式键在您的情况下是否可行，但这可能有助于解释为什么计算属性会过时。
Vue 响应式文档，了解更多信息: https://v2.vuejs.org/v2/guide/reactivity.html#Change-Detection-Caveats
关于javascript - Vue.js 计算属性不更新，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42678983/