所以基本上我一直在阅读相当多的教程,演示和API规范本身并没有走得太远,非常感谢你们的帮助。
我最近一直试图更好地掌握IndexedDBs并遇到一些问题,并希望对此代码提出一些批评/反馈。
此代码中有两个错误似乎无法修复。
首先加载方法init()被调用,它打开数据库并使用已存储的数据填充我的列表。尽管getAllDetails函数位于open函数之后,但控制台中的错误表明" db为null"。
使用deleteDetails函数的第二个问题是,当尝试删除任何索引时,控制台中的错误显示"在不允许突变的数据库上尝试进行变异操作。"
任何帮助都将非常感谢,我为大量的代码道歉!
聚苯乙烯。这都使用了使用FF 17和Chrome 22的本地主机服务器进行了测试。
var indexedDB = window.indexedDB || window.webkitIndexedDB || window.mozIndexedDB || window.msIndexedDB;
var IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction;
var IDBKeyRange = window.IDBKeyRange || window.webkitIDBKeyRange;
var Main = {};
Main.indexedDB = {};
Main.indexedDB.db = null;
Main.indexedDB.onerror = function(e) {
console.log(e);
};
function init() {
Main.indexedDB.open();
Main.indexedDB.getAllDetails();
}
Main.indexedDB.open = function () {
var request = indexedDB.open("DBV1",2);
//If no db exists or if the database is behind on versions then it will update.
//Though FF is the only browser atm that supports this method.
request.onupgradeneeded = function (e) {
console.log("Running UpgradeNeeded");
Main.indexedDB.db = e.target.result;
var thisDb = Main.indexedDB.db;
thisDb.onerror = function (e) {
alert("Sorry, an unforseen error was thrown.");
console.log("***ERROR***");
console.dir(e.target);
};
if (!thisDb.objectStoreNames.contains("Profile")) {
console.log("I need to make the Profile object store.");
thisDb.createObjectStore("Profile", { keyPath: "UserId", autoIncrement: true });
}
if (!thisDb.objectStoreNames.contains("Appointments")) {
console.log("I need to make the Appointments object store.");
thisDb.createObjectStore("Appointments", { keyPath: "AppointmentId", autoIncrement: true });
}
if (!thisDb.objectStoreNames.contains("Assignment")) {
console.log("I need to make the Assignment object store.");
var objectStore = thisDb.createObjectStore("Assignment", { keyPath: "AssignementId", autoIncrement: true });
}
}; //End-UpgradeNeeded
//To make this compatible with Chrome, the onsuccess method must be used.
request.onsuccess = function (e) {
console.log("This was successful.");
Main.indexedDB.db = e.target.result;
var thisDb = Main.indexedDB.db;
thisDb.onerror = function (e) {
alert("Sorry, an unforseen error was thrown.");
console.log("***ERROR***");
console.dir(e.target);
};
if (!thisDb.objectStoreNames.contains("Profile")) {
console.log("I need to make the Profile object store.");
thisDb.createObjectStore("Profile", { keyPath: "UserId", autoIncrement: true });
}
else{
}
if (!thisDb.objectStoreNames.contains("Appointments")) {
console.log("I need to make the Appointments object store.");
thisDb.createObjectStore("Appointments", { keyPath: "AppointmentId", autoIncrement: true });
}
else{
}
if (!thisDb.objectStoreNames.contains("Assignment")) {
console.log("I need to make the Assignment object store.");
thisDb.createObjectStore("Assignment", { keyPath: "AssignementId", autoIncrement: true });
}
else{
}
}; //End-onsuccess
request.onerror = function (e) {
alert("Sorry, an unforseen error was thrown.");
console.log("***ERROR***");
console.dir(e.target);
};
}; //End-OpenFunction
Main.indexedDB.addDetails = function (ProfName, AppointName) {
var db = Main.indexedDB.db;
console.log("Before Prof");
var transProf = db.transaction(["Profile"], "readwrite");
var storeProf = transProf.objectStore("Profile");
console.log("Before Appo");
var transAppo = db.transaction(["Appointments"], "readwrite");
var storeAppo = transAppo.objectStore("Appointments");
var dataProf = {
"text": ProfName
};
var dataAppo = {
"text": AppointName
};
var requestProf = storeProf.put(dataProf);
requestProf.onsuccess = function (e) {
console.log("Prof data successfully entered.");
};
requestProf.onerror = function (e) {
console.log(e);
};
var requestAppo = storeAppo.put(dataAppo);
requestAppo.onsuccess = function (e) {
console.log("Appo data successfully entered.");
};
requestAppo.onerror = function (e) {
console.log(e);
};
}; //End-AddDetails
function addDetails() {
var Prof = document.getElementById("ProfileName");
var Appo = document.getElementById("AppointmentName");
Main.indexedDB.addDetails(Prof.value, Appo.value);
Main.indexedDB.getAllDetails();
};
Main.indexedDB.getAllDetails = function () {
console.log("Get all called.");
var Prof = document.getElementById("Profile");
Prof.innerHTML = "";
var Appo = document.getElementById("Appointments");
Appo.innerHTML = "";
var db = Main.indexedDB.db;
var transProf = db.transaction(["Profile"], "readwrite");
var storeProf = transProf.objectStore("Profile");
var transAppo = db.transaction(["Appointments"], "readwrite");
var storeAppo = transAppo.objectStore("Appointments");
console.log("Stores and transactions created.");
//////////////////////////////////////////////////////////////////
var cursorRequestProf = storeProf.openCursor();
cursorRequestProf.onsuccess = function(e) {
var result = e.target.result;
if(!!result == false)
return;
renderUser(result.value, 1);
result.continue();
};
cursorRequestProf.onerror = Main.indexedDB.onerror;
/////////////////////////////////////////////////////////////////
var cursorRequestAppo = storeAppo.openCursor();
cursorRequestAppo.onsuccess = function(e) {
var result = e.target.result;
if(!!result == false)
return;
renderUser(result.value, 2);
result.continue();
};
cursorRequestAppo.onerror = Main.indexedDB.onerror;
/////////////////////////////////////////////////////////////////
console.log("Cursors complete.");
}; //End-GetAllDetails
function renderUser(row, column) {
if(column == 1){
var Users = document.getElementById("Profile");
}
else{
var Users = document.getElementById("Appointments");
}
var li = document.createElement("li");
var t = document.createTextNode(row.text);
li.appendChild(t);
Users.appendChild(li);
};
function deleteDetails(){
var deleteIndex = document.getElementById("DeleteNo");
Main.indexedDB.deleteIndex(deleteIndex.value);
Main.indexedDB.getAllDetails();
};
Main.indexedDB.deleteIndex = function(index){
var db = Main.indexedDB.db;
var transProf = db.transaction(["Profile"], "readwrite");
var storeProf = transProf.objectStore("Profile");
var transAppo = db.transaction(["Appointments"], "readwrite");
var storeAppo = transAppo.objectStore("Appointments");
var requestProf = storeProf.deleteIndex(index);
requestProf.onsuccess = function(e) {
console.log("Successful Prof delete");
};
requestProf.onerror = function(e) {
console.log("Error Prof Deleting: ", e);
};
var requestAppo = storeAppo.deleteIndex(index);
requestAppo.onsuccess = function(e) {
console.log("Successful Appo delete");
};
requestAppo.onerror = function(e) {
console.log("Error Appo Deleting: ", e);
};
};
答案 0 :(得分:1)
第一个问题:在open方法之后直接调用getAllDetails()。由于indexeddb API的异步特性,您无法执行此操作。必须先打开数据库,然后才能调用getAllDetails方法。这意味着您必须使用回调函数。
function init() {
Main.indexedDB.open(function (){Main.indexedDB.getAllDetails()});
}
Main.indexedDB.open = function (callback) {
var request = indexedDB.open("DBV1",2);
request.onupgradeneeded = function (e) { }
request.onsuccess = function (e) {
Main.indexedDB.db = e.target.result;
callback();
}
}
只有在调用onsuccess时,您才可以开始使用indexedDB。
第二个问题:只能在版本更改事务中删除索引。获得此类事务的唯一方法是使用更高版本号打开数据库。在这种情况下,可以在indexeddb.open请求的onupgradeneeded回调中访问版本更改事务。
有关indexeddb的详细信息,请选中my blog。