CODEWITHSUNDEEP
javascriptasynchronousindexeddb
Micah Henning
Micah Henning

Reputation: 2185

Waiting for IDBCursor.onsuccess to complete

I have an IndexedDB containing properties of various elements on the page. I have an index on one of those properties and I use a key range to get a specific list of results.

var key = IDBKeyRange.bound(10, 20);
var cursor = store.index('property').openCursor(key);

The problem I have is with the cursor.onsuccess function. It seems to execute for each result in the result set. Consequently, I can't execute a callback function once all of the results have been parsed.

cursor.onsuccess = function (e) {
    var cursor = e.target.result;
    if (cursor) {
        if (cursor.value.prop1 > 30 && cursor.value.prop2 < 80) {
            // Do stuff with result
            someArray.push({
                prop1: cursor.value.prop1,
                prop2: cursor.value.prop2
            }):
        }
    }
    cursor.continue();
};

Upvotes: 0

Views: 1032

Answers (2)

Deni Spasovski
Deni Spasovski

Reputation: 4129

Safest way to know that your action is finished is to use the transaction on complete event. This event is triggered after the cursor is closed.

transaction.oncomplete = function (event) {
    console.log('transaction completed');
};

Also to be sure that no error occurred add event listener to transaction events on error and on abort.

transaction.onerror = function (event) {
    console.log('transaction error');
};

transaction.onabort = function (event) {
    console.log('transaction abort');
};

Upvotes: 1

Micah Henning
Micah Henning

Reputation: 2185

As it turns out, cursor.onsuccess fires one last time with e.target.result undefined. You can execute a callback function when this happens:

cursor.onsuccess = function (e) {
    var cursor = e.target.result;
    if (cursor) {
        if (cursor.value.prop1 > 30 && cursor.value.prop2 < 80) {
            // Do stuff with result
            someArray.push({
                prop1: cursor.value.prop1,
                prop2: cursor.value.prop2
            }):
        }
    } else {
        // Execute code here
        console.log('There are ' + someArray.length + ' elements in someArray.');
    }
    cursor.continue();
};

Upvotes: 1

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