CRUD Operations

Basic create, read, update and delete operations with atRecords

In Dart, the AtClient is stored within the AtClientManager. Once an atSign has been onboarded, you will be able to access the AtClientManager for its associated atSign.


AtClientManager is a singleton model. When AtClientManager.getInstance() is called, it will get the AtClientManager instance for the last onboarded atSign.

AtClientManager atClientManager = AtClientManager.getInstance();

If you need simultaneous access to multiple atClients, you need to create a new isolate for each additional atClient, and onboard its atSign within the isolate.

An example of this pattern can be found in at_daemon_server.


As previously mentioned, the AtClientManager stores the actual AtClient itself. You can retrieve the AtClient by calling atClientManager.atClient.

AtClient atClient = atClientManager.atClient;


Before you can do anything with an atRecord, you need an atKey to represent it.

If you don't know how to create an atKey, please see the reference first.

The following examples use the self atKey phone.wavi@<current atSign>

It is up to the developer to modify the atKey according to their use case.

Creating / Updating Data

To create data the put method is used, this method accepts text (String) or binary (List<int>).

String currentAtSign = atClient.getCurrentAtSign()!;
AtKey myID = AtKey.self('phone', namespace: 'wavi',
                        sharedBy: currentAtSign).build();
String dataToStore = "123-456-7890";
bool res = await atClient.put(myID, dataToStore);
put signature
Future<bool> put(
    AtKey key,
    dynamic value,
    {bool  = false,
    PutRequestOptions? putRequestOptions});

Strongly Typed Methods

Since put accepts both String or List<int> as a value, the typing is dynamic. atClient also contains the strongly typed putText which only accepts String for the value, or putBinary which only accepts List<int> for the value.

To update existing data

Updating existing data is done by doing a put to the same atKey, this will overwrite any existing data stored in the atRecord.

List<int> binaryData = [1, 2, 3, 4];
bool res = await atClient.put(myID, binaryData);

The bytes [1, 2, 3, 4] have now replaced the string "123-456-7890".

Reading Data

There are two parts to reading data using the atClient SDK:

  1. Scanning for and listing out the atKeys for atRecords that can be retrieved

  2. Retrieving the atRecord for a given atKey

1. Scanning and listing atKeys

There are two methods available for scanning and listing atKeys:

  1. getAtKeys which provides the list in Class format (i.e. List<AtKey>)

  2. getKeys which provides the list in String format (i.e. List<String>)

Both methods accept the same parameters, only the return type is different. So we will show the more commonly used getAtKeys signature:

getAtKeys signature
Future<List<AtKey>> getAtKeys(
    {String? regex,
    String? sharedBy,
    String? sharedWith,
    bool showHiddenKeys = false});


A regular expression used to filter the list of atKeys.


Filter the list of atKeys to only include ones shared by a particular atSign.


Filter the list of atKeys to only include ones shared with a particular atSign.


A boolean flag to enable the inclusion of hidden atKeys (default = false)


Get all available (non-hidden) atKeys:

List<AtKey> allIDs = await atClient.getAtKeys();

All atKeys which end with ".wavi" in the record identifier part:

List<AtKey> waviIDs = await atClient.getAtKeys(regex: '^.*\.wavi@.+$');

2. Retrieving atRecords by atKey

To retrieve an atRecord, you must know the atKey and pass it to the get method.

get signature
Future<AtValue> get(
    AtKey key,
    {bool isDedicated = false,
    GetRequestOptions? getRequestOptions});

Calling this function will return an AtValue, and update the atKey passed to it with any changes to the metadata.


AtValue atValue = await atClient.get(myID);
String? text = atValue.;

Deleting Data

To delete data, simply call the delete method with the atKey for the atRecord to delete.

delete signature
Future<bool> delete(
    AtKey key,
    {bool isDedicated = false});


bool res = await atClient.delete(myID);

API Docs

You can find the API reference for the entire package available on pub.

The AtClient class API reference is available here.

Last updated

© 2023 Atsign