Vis.js comes with a flexible DataSet, which can be used to hold and manipulate unstructured data and listen for changes in the data. The DataSet is key/value based. Data items can be added, updated and removed from the DatSet, and one can subscribe to changes in the DataSet. The data in the DataSet can be filtered and ordered, and fields (like dates) can be converted to a specific type. Data can be normalized when appending it to the DataSet as well.
The following example shows how to use a DataSet.
// create a DataSet var options = {}; var data = new vis.DataSet(options); // add items // note that the data items can contain different properties and data formats data.add([ {id: 1, text: 'item 1', date: new Date(2013, 6, 20), group: 1, first: true}, {id: 2, text: 'item 2', date: '2013-06-23', group: 2}, {id: 3, text: 'item 3', date: '2013-06-25', group: 2}, {id: 4, text: 'item 4'} ]); // subscribe to any change in the DataSet data.on('*', function (event, properties, senderId) { console.log('event', event, properties); }); // update an existing item data.update({id: 2, group: 1}); // remove an item data.remove(4); // get all ids var ids = data.getIds(); console.log('ids', ids); // get a specific item var item1 = data.get(1); console.log('item1', item1); // retrieve a filtered subset of the data var items = data.get({ filter: function (item) { return item.group == 1; } }); console.log('filtered items', items); // retrieve formatted items var items = data.get({ fields: ['id', 'date'], convert: { date: 'ISODate' } }); console.log('formatted items', items);
A DataSet can be constructed as:
var data = new vis.DataSet([data] [, options])
After construction, data can be added to the DataSet using the methods
add
and update
, as described in section
Data Manipulation.
The parameter data
code> is optional and can be an Array or
Google DataTable with items.
The parameter options
is optional and is an object which can
contain the following properties:
Name | Type | Default value | Description |
---|---|---|---|
fieldId | String | "id" |
The name of the field containing the id of the items.
When data is fetched from a server which uses some specific
field to identify items, this field name can be specified
in the DataSet using the option fieldId .
For example CouchDB uses the field
"_id" to identify documents.
|
convert | Object.<String, String> | none | An object containing field names as key, and data types as value. By default, the type of the properties of items are left unchanged. Item properties can be normalized by specifying a field type. This is useful for example to automatically convert stringified dates coming from a server into JavaScript Date objects. The available data types are listed in section Data Types. |
DataSet contains the following methods.
Method | Return Type | Description |
---|---|---|
add(data [, senderId]) | Number[] | Add data to the DataSet. Adding an item will fail when there already is an item with the same id. The function returns an array with the ids of the added items. See section Data Manipulation. |
clear([senderId]) | Number[] | Clear all data from the DataSet. The function returns an array with the ids of the removed items. |
distinct(field) | Array | Find all distinct values of a specified field. Returns an unordered array containing all distinct values. If data items do not contain the specified field are ignored. |
forEach(callback [, options]) | none | Execute a callback function for every item in the dataset. The available options are described in section Data Selection. |
get([options] [, data]) get(id [,options] [, data]) get(ids [, options] [, data]) |
Object | Array | DataTable |
Get a single item, multiple items, or all items from the DataSet.
Usage examples can be found in section Getting Data, and the available options are described in section Data Selection. If parameter data isprovided, items will be appended to this array or table, which is required in case of Google DataTable.
|
getIds([options]) | Number[] |
Get ids of all items or of a filtered set of items.
Available options are described in section Data Selection, except that options fields and convert are not applicable in case of getIds .
|
map(callback [, options]) | Array | Map every item in the DataSet. The available options are described in section Data Selection. |
max(field) | Object | null |
Find the item with maximum value of specified field. Returns null if no item is found.
|
min(field) | Object | null |
Find the item with minimum value of specified field. Returns null if no item is found.
|
off(event, callback) | none | Unsubscribe from an event, remove an event listener. See section Subscriptions. |
on(event, callback) | none | Subscribe to an event, add an event listener. See section Subscriptions. |
remove(id [, senderId]) remove(ids [, senderId]) |
Number[] | Remove on ore multiple items by id or by the items themselves. Returns an array with the ids of the removed items. See section Data Manipulation. |
update(id [, senderId]) update(ids [, senderId]) |
Number[] | Update on ore existing items. When an item doesn't exist, it will be created. Returns an array with the ids of the removed items. See section Data Manipulation. |
One can subscribe on changes in a DataSet.
A subscription can be created using the method on
,
and removed with off
.
// create a DataSet var data = new vis.DataSet(); // subscribe to any change in the DataSet data.on('*', function (event, properties, senderId) { console.log('event:', event, 'properties:', properties, 'senderId:', senderId); }); // add an item data.add({id: 1, text: 'item 1'}); // triggers an 'add' event data.update({id: 1, text: 'item 1 (updated)'}); // triggers an 'update' event data.remove(1); // triggers an 'remove' event
Subscribe to an event.
Syntax:DataSet.on(event, callback)Where:
event
is a String containing any of the events listed
in section Events.
callback
is a callback function which will be called
each time the event occurs. The callback function is described in
section Callback.
Unsubscribe from an event.
Syntax:DataSet.off(event, callback)Where
event
and callback
correspond with the
parameters used to subscribe to the event.
The following events are available for subscription:
Event | Description |
---|---|
add |
The add event is triggered when an item
or a set of items is added, or when an item is updated while
not yet existing.
|
update |
The update event is triggered when an existing item
or a set of existing items is updated.
|
remove |
The remove event is triggered when an item
or a set of items is removed.
|
* |
The * event is triggered when any of the events
add , update , and remove
occurs.
|
The callback functions of subscribers are called with the following parameters:
function (event, properties, senderId) { // handle the event });
where the parameters are defined as
Parameter | Type | Description |
---|---|---|
event | String |
Any of the available events: add ,
update , or remove .
|
properties | Object | null |
Optional properties providing more information on the event.
In case of the events add ,
update , and remove ,
properties is always an object containing a property
items, which contains an array with the ids of the affected
items.
|
senderId | String | Number |
An senderId, optionally provided by the application code
which triggered the event. If senderId is not provided, the
argument will be null .
|
The data in a DataSet can be manipulated using the methods
add
,
update
,
and remove
.
The DataSet can be emptied using the method
clear
.
// create a DataSet var data = new vis.DataSet(); // add items data.add([ {id: 1, text: 'item 1'}, {id: 2, text: 'item 2'}, {id: 3, text: 'item 3'} ]); // update an item data.update({id: 2, text: 'item 2 (updated)'}); // remove an item data.remove(3);
Add a data item or an array with items.
Syntax:var addedIds = DataSet.add(data [, senderId])The argument
data
can contain:
Object
containing a single item to be
added. The item must contain an id.
Array
or
google.visualization.DataTable
containing
a list with items to be added. Each item must contain
an id.
After the items are added to the DataSet, the DataSet will
trigger an event add
. When a senderId
is provided, this id will be passed with the triggered
event to all subscribers.
The method will throw an Error when an item with the same id as any of the added items already exists.
Update a data item or an array with items.
Syntax:var updatedIds = DataSet.update(data [, senderId])The argument
data
can contain:
Object
containing a single item to be
updated. The item must contain an id.
Array
or
google.visualization.DataTable
containing
a list with items to be updated. Each item must contain
an id.
The provided properties will be merged in the existing item. When an item does not exist, it will be created.
After the items are updated, the DataSet will
trigger an event add
for the added items, and
an event update
. When a senderId
is provided, this id will be passed with the triggered
event to all subscribers.
Remove a data item or an array with items.
Syntax:var removedIds = DataSet.remove(id [, senderId])
The argument id
can be:
Number
or String
containing the id
of a single item to be removed.
Object
containing the item to be deleted.
The item will be deleted by its id.
The method ignores removal of non-existing items, and returns an array containing the ids of the items which are actually removed from the DataSet.
After the items are removed, the DataSet will
trigger an event remove
for the removed items.
When a senderId
is provided, this id will be passed with
the triggered event to all subscribers.
Clear the complete DataSet.
Syntax:var removedIds = DataSet.clear([senderId])
After the items are removed, the DataSet will
trigger an event remove
for all removed items.
When a senderId
is provided, this id will be passed with
the triggered event to all subscribers.
The DataSet contains functionality to format, filter, and sort data retrieved via the
methods get
, getIds
, forEach
, and map
. These methods have the following syntax:
DataSet.get([id] [, options] [, data]); DataSet.getIds([options]); DataSet.forEach(callback [, options]); DataSet.map(callback [, options]);
Where options
is an Object which can have the following
properties:
Name | Type | Description |
---|---|---|
fields | String[ ] |
An array with field names.
By default, all properties of the items are emitted.
When fields is defined, only the properties
whose name is specified in fields will be included
in the returned items.
|
convert | Object.<String, String> | An object containing field names as key, and data types as value. By default, the type of the properties of an item are left unchanged. When a field type is specified, this field in the items will be converted to the specified type. This can be used for example to convert ISO strings containing a date to a JavaScript Date object, or convert strings to numbers or vice versa. The available data types are listed in section Data Types. |
filter | Function | Items can be filtered on specific properties by providing a filter function. A filter function is executed for each of the items in the DataSet, and is called with the item as parameter. The function must return a boolean. All items for which the filter function returns true will be emitted. See section Data Filtering. |
order | String | Function | Order the items by a field name or custom sort function. |
The following example demonstrates formatting properties and filtering properties from items.
// create a DataSet var data = new vis.DataSet(); data.add([ {id: 1, text: 'item 1', date: '2013-06-20', group: 1, first: true}, {id: 2, text: 'item 2', date: '2013-06-23', group: 2}, {id: 3, text: 'item 3', date: '2013-06-25', group: 2}, {id: 4, text: 'item 4'} ]); // retrieve formatted items var items = data.get({ fields: ['id', 'date', 'group'], // output the specified fields only convert: { date: 'Date', // convert the date fields to Date objects group: 'String' // convert the group fields to Strings } });
Data can be retrieved from the DataSet using the method get
.
This method can return a single item or a list with items.
A single item can be retrieved by its id:
var item1 = dataset.get(1);
A selection of items can be retrieved by providing an array with ids:
var items = dataset.get([1, 3, 4]); // retrieve items 1, 3, and 4
All items can be retrieved by simply calling get
without
specifying an id:
var items = dataset.get(); // retrieve all items
Items can be filtered on specific properties by providing a filter function. A filter function is executed for each of the items in the DataSet, and is called with the item as parameter. The function must return a boolean. All items for which the filter function returns true will be emitted.
// retrieve all items having a property group with value 2 var group2 = dataset.get({ filter: function (item) { return (item.group == 2); } }); // retrieve all items having a property balance with a value above zero var positiveBalance = dataset.get({ filter: function (item) { return (item.balance > 0); } });
DataSet supports the following data types:
Name | Description | Examples |
---|---|---|
Boolean | A JavaScript Boolean |
true false
|
Number | A JavaScript Number |
32 2.4
|
String | A JavaScript String |
"hello world" "2013-06-28"
|
Date | A JavaScript Date object |
new Date() new Date(2013, 5, 28) new Date(1372370400000)
|
Moment | A Moment object, created with moment.js |
moment() moment('2013-06-28')
|
ISODate | A string containing an ISO Date |
new Date().toISOString() "2013-06-27T22:00:00.000Z"
|
ASPDate | A string containing an ASP Date |
"/Date(1372370400000)/" "/Date(1198908717056-0700)/"
|
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