In a Chrome Extension, I have no problem adding, updating, and removing data to/from an IndexedDB database accessed by my service worker with Chrome Runtime Messaging sent from my content script. My trouble is doing a full table read from my content script. I do a console.log() to dump out the property before I send it back in my sendResponse in the Chrome Runtime Messaging, and I see the data there properly, but the content script receives an undefined
. I assume this is because of the asynchronous nature of getting the data. I tried promises and async/await and the combination thereof and I just can't seem to get anything except an undefined
in my content script on the message back from the service worker. I also ran sending a test array back and that worked just fine -- but receiving the IndexedDB table data does not work in the message passing. I also tried to JSONify the data and that didn't help either. What's the catch?
service-worker.js
importScripts('modules/idb.js');
var SW = {};
SW.onReady = function(){
chrome.runtime.onMessage.addListener(function(o, sender, sendResponse) {
(o.readTable) && sendResponse(SW.readTable(o,sender));
});
};
SW.readTable = function(o,sender){
var sTable = o.table;
new Promise((resolve) => {
IDB.readTable(sTable,function(asEntries){
resolve(asEntries);
});
}).then((asEntries) => {
console.log('SW asEntries',asEntries); // this shows me valid data in tests
var o = {};
// can also change this to fake data with asEntries being a string array and bug goes away in content.js
o.response = asEntries;
return o;
});
};
SW.onReady();
modules/idb.js
var IDB = {};
// Requires storage (or, even better, unlimitedStorage) permission in your manifest.json file.
// Note also that dev console of service worker will not show data -- have to use toolbar button popup panel (if you have one) and
// dev console from there, or code to access it, which sucks.
IDB.connectStore = function(sTable,sReadWriteSetting,fn){
var conn = indexedDB.open('unlimitedStorage', 1);
conn.onupgradeneeded = function(e) {
var db = e.target.result;
db.createObjectStore(sTable);
};
conn.onsuccess = function(e) {
var db = e.target.result;
var tx = db.transaction(sTable,sReadWriteSetting);
var store = tx.objectStore(sTable);
fn(db,tx,store);
};
};
IDB.addToTable = function(sTable,sKey,sVal){
IDB.connectStore(sTable,'readwrite',function(db,tx,store){
if ((sKey === undefined) || (sKey === '') || (sKey === null) || (sKey === false)) { // auto key by increment
var req = store.count();
req.onsuccess = function(e){
sKey = e.target.result 1;
store.add(sVal,sKey);
tx.complete;
}
} else {
store.add(sVal,sKey);
tx.complete;
}
});
};
IDB.removeFromTable = function(sTable,sKey){
IDB.connectStore(sTable,'readwrite',function(db,tx,store){
store.delete(sKey);
tx.complete;
});
};
IDB.readTableByKey = function(sTable,sKey,fn){
IDB.connectStore(sTable,'readonly',function(db,tx,store){
var req = store.get(sKey);
req.onerror = function(e){
fn(e.target.result);
}
req.onsuccess = function(e){
fn(e.target.result);
}
});
};
IDB.readTable = function(sTable,fn){
IDB.connectStore(sTable,'readonly',function(db,tx,store){
var req = store.getAll();
req.onerror = function(e){
fn(e.target.result);
}
req.onsuccess = function(e){
fn(e.target.result);
}
});
};
content.js
var CONTENT = {};
CONTENT.onReady = function(){
var o = {};
o.readTable = true;
o.table = 'loadTimes';
chrome.runtime.sendMessage(o,function(response){
if (response.response) { // errors here with response property being undefined
console.log('CONTENT RCVD asEntries',response.response);
}
});
};
CONTENT.onReady();
CodePudding user response:
Chrome extensions API, unlike Firefox WebExtensions, can't handle Promise returned from a callback or provided in sendResponse, https://crbug.com/1185241.
There's also a bug in your readTable: you need to add return
before new Promise((resolve)
The solution is two-fold:
- Use
return true
from the callback to allow asynchronous sendResponse - Call
sendReponse
inside.then
of a Promise chain.
chrome.runtime.onMessage.addListener(function(o, sender, sendResponse) {
if (o.readTable) {
SW.readTable(o,sender).then(sendResponse);
return true;
} else {
sendResponse(); // Chrome 99-101 bug workaround, https://crbug.com/1304272
}
});
CodePudding user response:
The fix is to return data in a different message thread:
In the service worker in
SW.readTable()
, just return variableo
witho.response = true
and then ignore the response in the content script.Before returning the variable
o
fromSW.readTable()
, do achrome.runtime.sendMessage({readTableResult = true, data: asEntries},function(response){ /* ignore response */});
In the content script, ignore any response back from the
readTable
message. So, theif (response.response) {...}
condition can be eliminated.In the content script, add a message listener with
chrome.runtime.onMessage.addListener(o, sender, sendResponse)
and look for the condition(o.readTableResult)
. Once received, theo.data
will now contain theasEntries
data.