IDBObjectStore: get() method
Note: This feature is available in Web Workers.
The get()
method of the IDBObjectStore
interface returns an IDBRequest
object, and, in a separate thread,
returns the object selected by the specified key. This is for retrieving
specific records from an object store.
If a value is successfully found, then a structured clone of it is created and set as
the result
of the
request object.
Note:
This method produces the same result for: a) a record that doesn't exist in the database and b) a record that has an undefined value.
To tell these situations apart, call the openCursor()
method with the same key. That method provides a cursor if the record exists, and no cursor if it does not.
Syntax
get(key)
Parameters
key
-
The key or key range that identifies the record to be retrieved.
Return value
An IDBRequest
object on which subsequent events related to this operation are fired.
If the operation is successful, the value of the request's result
property is the value of the first record matching the given key or key range.
Exceptions
This method may raise a DOMException
of one of the following types:
TransactionInactiveError
DOMException
-
Thrown if this
IDBObjectStore
's transaction is inactive. DataError
DOMException
-
Thrown if key or key range provided contains an invalid key.
InvalidStateError
DOMException
-
Thrown if the
IDBObjectStore
has been deleted or removed.
Examples
In the following code snippet, we open a read/write transaction on our database and get
one specific record from object store using get()
— a sample record with
the key "Walk dog". Once this data object is retrieved, you could then update it using
normal JavaScript, then put it back into the database using a
IDBObjectStore.put
operation. For a full working example, see our To-do Notifications app
(view example live).
// Let us open our database
const DBOpenRequest = window.indexedDB.open("toDoList", 4);
DBOpenRequest.onsuccess = (event) => {
note.appendChild(document.createElement("li")).textContent =
"Database initialized.";
// store the result of opening the database in the db variable.
// This is used a lot below
db = DBOpenRequest.result;
// Run the getData() function to get the data from the database
getData();
};
function getData() {
// open a read/write db transaction, ready for retrieving the data
const transaction = db.transaction(["toDoList"], "readwrite");
// report on the success of the transaction completing, when everything is done
transaction.oncomplete = (event) => {
note.appendChild(document.createElement("li")).textContent =
"Transaction completed.";
};
transaction.onerror = (event) => {
note.appendChild(document.createElement("li")).textContent =
`Transaction not opened due to error: ${transaction.error}`;
};
// create an object store on the transaction
const objectStore = transaction.objectStore("toDoList");
// Make a request to get a record by key from the object store
const objectStoreRequest = objectStore.get("Walk dog");
objectStoreRequest.onsuccess = (event) => {
// report the success of our request
note.appendChild(document.createElement("li")).textContent =
"Request successful.";
const myRecord = objectStoreRequest.result;
};
}
Specifications
Specification |
---|
Indexed Database API 3.0 # ref-for-dom-idbobjectstore-get① |
Browser compatibility
BCD tables only load in the browser
See also
- Using IndexedDB
- Starting transactions:
IDBDatabase
- Using transactions:
IDBTransaction
- Setting a range of keys:
IDBKeyRange
- Retrieving and making changes to your data:
IDBObjectStore
- Using cursors:
IDBCursor
- Reference example: To-do Notifications (View the example live).