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Data loading

There are several ways of loading List items:

  • on initialization of List
  • after initialization of List

First, you need to prepare a data set that will be loaded into List.

Preparing data set​

dhtmlxList expects loaded data in the JSON format. Here is an example of an appropriate data set:

var dataset = [
    {"value": "1st item", "id": "1"},
    {"value": "2nd item", "id": "2"},
    {"value": "3rd item", "id": "3"},
    {"value": "4th item", "id": "4"}
]

Each object in the data set contains a number of key:value pairs that represent attributes of List items. You can specify your own template of rendering List items with the help of the template configuration option.

Loading data on initialization​

You can load a predefined data set into List on the initialization stage. Use the data configuration property, as in:

const list = new dhx.List("list", {
    css: "dhx_widget--bordered",
    template: template,
    itemHeight: 72,
    data: dataset
});

Related sample: List. Initialization with config.data

Loading data after initialization​

There are two ways to load data into Grid after its initialization:

External data loading​

To load data from an external file, make use of the load() method of DataCollection. It takes the URL of the file with data as a parameter:

var list = new dhx.List("list_container", {
    template: template,
    itemHeight: 72
});
list.data.load("../common/dataset.json");

The component will make an AJAX call and expect the remote URL to provide valid JSON data.

Data loading is asynchronous, so you need to wrap any after-loading code into a promise:

list.data.load("/some/data").then(function(){
   // some logic here
});

Related sample: List. Initialization with data.load()

Loading from local source​

To load data from a local data source, use the parse() method of DataCollection. Pass a predefined data set as a parameter of this method:

var list = new dhx.List("list_container", {
    template: template,
    itemHeight: 72
});
list.data.parse(dataset);

Related sample: List. Initialization with data.parse()

Saving and restoring state​

To save the current state of a list, use the serialize() method of DataCollection. It converts the data of a list into an array of JSON objects. Each JSON object contains a set of key:value pairs that represent attributes of List items.

var state = list1.data.serialize();

Then you can parse the data stored in the saved state array to a different list. For example:

// creating a new list
var list2 = new dhx.List(document.body);
// parsing the state of list1 into list2
list2.data.parse(state);

Dynamic loading​

Pro version only

This functionality requires PRO version of the DHTMLX suite package.

note

To make use of dynamic data loading, switch the virtual property on.

To enable dynamic data loading in List you need to:

new dhx.LazyDataProxy("https://docs.dhtmlx.com/suite/backend/lazyload", {
    limit: 30,
    prepare: 5,
    delay: 150,
    from: 0
});
  • load data into List via the load method of Data Collection and pass lazyDataProxy as a parameter of this method:
var list = new dhx.list("list_container", {
    virtual: true
});
list.data.load(lazyDataProxy);

Related sample: List. External data lazy loading

note

The following methods of DataCollection will not work until all data are loaded into List: add, remove, copy, move, update, changeId, sort, filter.