集合尚未初始化-Sharepoint Javascript

尝试获取列表集合的枚举数时，我遇到以下错误：“未捕获错误：集合尚未初始化。尚未请求或未执行请求。可能需要显式请求。”

它发生在

var listEnumerator=lists.getEnumerator（）行在我看来，试图使用
context.load（list）将列表加载到客户机对象中时出现了问题

这是我的代码中导致问题的部分。在抛出错误之前，我已经标记了位置

//____________________________Required function for accessing the host site's info.___________________________________
function getQueryStringParameter(param) {
var params = document.URL.split("?")[1].split("&");    
for (var i = 0; i < params.length; i = i + 1) {
    var singleParam = params[i].split("=");
    if (singleParam[0] == param) {
        return singleParam[1];
}   
}
}

//____________________________Begin checking for list_________________________
function checkForList(listToFind, typeOfListToCreateIfTheListIsMissing)
{
    var hostUrl = decodeURIComponent(getQueryStringParameter("SPHostUrl"));
    var hostcontext = new SP.AppContextSite(context, hostUrl);
    var hostweb = hostcontext.get_web();

    var lists = hostweb.get_lists();
    context.load(lists);
    context.executeQueryAsync(checkIfListExistsUsingEnumerator(listToFind, lists, hostweb, typeOfListToCreateIfTheListIsMissing), onQueryFailed);
}
//Failed to get lists for some reason
function onQueryFailed(sender, args) {  
    alert('We failed to retrieve lists. \n' + args.get_message() + '\n' + args.get_stackTrace());  
}

//____________________________Does list exist?____________________________
function checkIfListExistsUsingEnumerator(listToFind, lists, hostweb, typeOfList)
{   
    var listExists = false; 
    //!!!!!!!!!!!!!!! ERROR HERE !!!!!!!!!!!!!!!!       
    var listEnumerator = lists.getEnumerator();
    var title;
    while (listEnumerator.moveNext()) 
    {
        title = listEnumerator.get_current().get_title();  

        if (title == listToFind)
        {  
            listExists = true;              
        }  
    }

    if (!listExists) 
    {
        alert("It appears that a required list does not already exist. \nClick ok, and we'll automatically create one for you.");
        //Create a new list
        createList(listToFind, hostweb, typeOfList); 
    }
    else if (listExists)
    {
        //Do nothing.
    }         
}

//____________________________If it doesn't, create one on the local site____________________________
function createList(nameOfNewList, hostweb, typeOfList) {
    var listCreationInfo = new SP.ListCreationInformation();
    listCreationInfo.set_title(nameOfNewList);

    if (typeOfList === "events")
    {
        listCreationInfo.set_templateType(SP.ListTemplateType.events);
    }
    else if (typeOfList === "contacts")
    {
        listCreationInfo.set_templateType(SP.ListTemplateType.contacts);
    }
    var lists = hostweb.get_lists();
    var newList = lists.add(listCreationInfo);
    context.load(newList);
    context.executeQueryAsync(onListCreationSuccess, onListCreationFail);
}

function onListCreationSuccess() {
    alert('List created successfully!');
}

function onListCreationFail(sender, args) {
    alert('Failed to create the list. ' + args.get_message());
}

到一个同步的

context.executeQuery(checkIfListExists(listToFind, hostweb, typeOfListToCreateIfTheListIsMissing), onQueryFailed); 

我已经想出了一个替代的、更短的方法来达到我以前试图达到的目标

我没有检查列表是否已经存在，而是尝试创建一个列表，如果列表已经存在，查询将无法创建列表。（这很好，因为如果列表已经存在，我不想覆盖它。）

我不完全确定我在这里所做的是否有任何不希望的副作用，但在我的测试中，它产生了期望的行为

//____________________________Required function for accessing the host site's info.___________________________________
function getQueryStringParameter(param) {
var params = document.URL.split("?")[1].split("&");    
for (var i = 0; i < params.length; i = i + 1) {
    var singleParam = params[i].split("=");
    if (singleParam[0] == param) {
        return singleParam[1];
}   
}
}

//____________________________Create a list if one does not already exist_________________________
function createList(listToCreate, typeOfList)
{
    // Create an announcement SharePoint list with the name that the user specifies.
    var hostUrl = decodeURIComponent(getQueryStringParameter("SPHostUrl"));
    var hostContext = new SP.AppContextSite(currentContext, hostUrl);
    var hostweb = hostContext.get_web();
    var listCreationInfo = new SP.ListCreationInformation();

    listCreationInfo.set_title(listToCreate);

    if (typeOfList === "events")
    {
        listCreationInfo.set_templateType(SP.ListTemplateType.events);
    }
    else if (typeOfList === "contacts")
    {
        listCreationInfo.set_templateType(SP.ListTemplateType.contacts);
    }
    var lists = hostweb.get_lists();
    var newList = lists.add(listCreationInfo);
    currentContext.load(newList);
    currentContext.executeQueryAsync(onListCreationSuccess, onListCreationFail);     
}

function onListCreationSuccess() {
    alert("We've created a list since one doesn't exist yet." );
}

function onListCreationFail(sender, args) {
    alert("We didn't create the list. Here's why: " + args.get_message());
}

/\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu___________________________________
函数getQueryStringParameter（参数）{
var params=document.URL.split（“？”[1]。split（“&”）；
对于（变量i=0；i
您有一个输入错误。您的上下文变量名为“currentcontext”，但当您调用load方法时，您使用的是“context”变量。尝试将其更改为“currentcontext”变量。谢谢，但这并不能解决我的问题。这里没有看到，但我在代码的最开始创建了一个名为context的上下文变量——currentcontext行是多余的/不需要的，应该删除它。（我现在将编辑问题以删除它。）您的
context
变量来自哪里？
var currentContext=SP.ClientContext.get_current（）在程序的最开始。
//____________________________Required function for accessing the host site's info.___________________________________
function getQueryStringParameter(param) {
var params = document.URL.split("?")[1].split("&");    
for (var i = 0; i < params.length; i = i + 1) {
    var singleParam = params[i].split("=");
    if (singleParam[0] == param) {
        return singleParam[1];
}   
}
}

//____________________________Create a list if one does not already exist_________________________
function createList(listToCreate, typeOfList)
{
    // Create an announcement SharePoint list with the name that the user specifies.
    var hostUrl = decodeURIComponent(getQueryStringParameter("SPHostUrl"));
    var hostContext = new SP.AppContextSite(currentContext, hostUrl);
    var hostweb = hostContext.get_web();
    var listCreationInfo = new SP.ListCreationInformation();

    listCreationInfo.set_title(listToCreate);

    if (typeOfList === "events")
    {
        listCreationInfo.set_templateType(SP.ListTemplateType.events);
    }
    else if (typeOfList === "contacts")
    {
        listCreationInfo.set_templateType(SP.ListTemplateType.contacts);
    }
    var lists = hostweb.get_lists();
    var newList = lists.add(listCreationInfo);
    currentContext.load(newList);
    currentContext.executeQueryAsync(onListCreationSuccess, onListCreationFail);     
}

function onListCreationSuccess() {
    alert("We've created a list since one doesn't exist yet." );
}

function onListCreationFail(sender, args) {
    alert("We didn't create the list. Here's why: " + args.get_message());
}