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Lookup - Basics

The Lookup component allows users to search through its drop-down list and select a single item. The drop-down list can be grouped by category.

Backend API
@model IEnumerable<string> @using DevExtreme.AspNet.Mvc.Builders; <div class="dx-fieldset"> <div class="dx-fieldset-header">Simple lookup</div> <div class="dx-field"> @(Html.DevExtreme().Lookup() .DataSource(Model) .DropDownOptions(p => p.ShowTitle(false)) .Value(Model.First()) .InputAttr("aria-label", "Simple lookup") ) </div> </div> <div class="dx-fieldset"> <div class="dx-fieldset-header">Grouped lookup</div> <div class="dx-field"> @(Html.DevExtreme().Lookup() .DataSource(d => d.Mvc() .Controller("EmployeesTasks") .LoadAction("Get") .Key("ID") ) .DataSourceOptions(o => o.Group("Assigned")) .DropDownOptions(p => p.HideOnOutsideClick(true) .ShowTitle(false) ) .Grouped(true) .DisplayExpr("Subject") .InputAttr("aria-label", "Grouped lookup") ) </div> </div>
using DevExtreme.NETCore.Demos.Models.SampleData; using System; using System.Collections.Generic; using System.Linq; using Microsoft.AspNetCore.Mvc; namespace DevExtreme.NETCore.Demos.Controllers { public class LookupController : Controller { public ActionResult Basics() { return View(SampleData.EmployeesList); } } }
using DevExtreme.AspNet.Data; using DevExtreme.AspNet.Mvc; using DevExtreme.NETCore.Demos.Models.Northwind; using DevExtreme.NETCore.Demos.Models.SampleData; using Microsoft.AspNetCore.Mvc; using System; using System.Linq; namespace WidgetGallery.Controllers { [Route("api/[controller]")] public class EmployeesTasksController : Controller { [HttpGet] public object Get(DataSourceLoadOptions loadOptions) { return DataSourceLoader.Load(SampleData.EmployeesTasks, loadOptions); } } }
using System; using System.Collections.Generic; using System.Linq; namespace DevExtreme.NETCore.Demos.Models.SampleData { public partial class SampleData { public static readonly IEnumerable<string> EmployeesList = new[] { "John Heart", "Samantha Bright", "Arthur Miller", "Robert Reagan", "Greta Sims", "Brett Wade", "Sandra Johnson", "Ed Holmes", "Barb Banks", "Kevin Carter", "Cindy Stanwick", "Sammy Hill", "Davey Jones", "Victor Norris", "Mary Stern", "Robin Cosworth", "Kelly Rodriguez", "James Anderson", "Antony Remmen", "Olivia Peyton", "Taylor Riley", "Amelia Harper", "Wally Hobbs", "Brad Jameson", "Karen Goodson", "Marcus Orbison", "Sandy Bright", "Morgan Kennedy", "Violet Bailey", "Ken Samuelson", "Nat Maguiree", "Bart Arnaz", "Leah Simpson", "Arnie Schwartz", "Billy Zimmer", "Samantha Piper", "Maggie Boxter", "Terry Bradley", "Gabe Jones", "Lucy Ball", "Jim Packard", "Hannah Brookly", "Harv Mudd", "Clark Morgan", "Todd Hoffman", "Jackie Garmin", "Lincoln Bartlett", "Brad Farkus", "Jenny Hobbs", "Dallas Lou", "Stu Pizaro" }; } }
using System; using System.Collections.Generic; using System.Linq; namespace DevExtreme.NETCore.Demos.Models.SampleData { public partial class SampleData { public static readonly IEnumerable<EmployeeTask> EmployeesTasks = new[] { new EmployeeTask { ID = 1, Assigned = "Mr. John Heart", Subject = "Choose between PPO and HMO Health Plan" }, new EmployeeTask { ID = 2, Assigned = "Mr. John Heart", Subject = "Google AdWords Strategy" }, new EmployeeTask { ID = 3, Assigned = "Mr. John Heart", Subject = "New Brochures" }, new EmployeeTask { ID = 4, Assigned = "Mr. John Heart", Subject = "Update NDA Agreement" }, new EmployeeTask { ID = 5, Assigned = "Mr. John Heart", Subject = "Review Product Recall Report by Engineering Team" }, new EmployeeTask { ID = 6, Assigned = "Mrs. Olivia Peyton", Subject = "Update Personnel Files" }, new EmployeeTask { ID = 7, Assigned = "Mrs. Olivia Peyton", Subject = "Review Health Insurance Options Under the Affordable Care Act" }, new EmployeeTask { ID = 8, Assigned = "Mrs. Olivia Peyton", Subject = "Non-Compete Agreements" }, new EmployeeTask { ID = 9, Assigned = "Mrs. Olivia Peyton", Subject = "Give Final Approval for Refunds" }, new EmployeeTask { ID = 10, Assigned = "Mr. Robert Reagan", Subject = "Deliver R&D Plans for 2013" }, new EmployeeTask { ID = 11, Assigned = "Mr. Robert Reagan", Subject = "Decide on Mobile Devices to Use in the Field" }, new EmployeeTask { ID = 12, Assigned = "Mr. Robert Reagan", Subject = "Try New Touch-Enabled WinForms Apps" }, new EmployeeTask { ID = 13, Assigned = "Mr. Robert Reagan", Subject = "Approval on Converting to New HDMI Specification" }, new EmployeeTask { ID = 14, Assigned = "Ms. Greta Sims", Subject = "Approve Hiring of John Jeffers" }, new EmployeeTask { ID = 15, Assigned = "Ms. Greta Sims", Subject = "Update Employee Files with New NDA" }, new EmployeeTask { ID = 16, Assigned = "Ms. Greta Sims", Subject = "Provide New Health Insurance Docs" } }; } }
using Newtonsoft.Json; using Newtonsoft.Json.Converters; using System; using System.Collections.Generic; namespace DevExtreme.NETCore.Demos.Models { [JsonConverter(typeof(StringEnumConverter))] public enum Priority { High, Normal, Low, Urgent } public class EmployeeAppointment : Appointment { public Priority Priority { set; get; } public IEnumerable<int> OwnerId { get; set; } } public class EmployeeTask { public int ID { set; get; } public string Subject { set; get; } public DateTime StartDate { set; get; } public DateTime DueDate { set; get; } public string Status { set; get; } public Priority Priority { set; get; } public int Completion { set; get; } public IEnumerable<int> OwnerId { get; set; } public string Assigned { get; set; } public string RecurrenceRule { get; set; } } }
.dx-theme-generic .dx-fieldset, .dx-theme-material .dx-fieldset { width: 40%; float: left; } .dx-field > .dx-lookup { flex: 1; }

Bind the Component to Data

To bind the component to data, use one of these properties:

  • items[]
    Accepts a local data array (see the Simple Lookup code below).

  • dataSource
    Accepts a local data array or a DataSource object. This object works with local and remote arrays and allows you to shape data. In this demo, a DataSource instance is configured to group a local array of objects (see the Grouped Lookup code below).

Both properties work with arrays of primitives or objects. If you use objects, specify the following properties:

  • valueExpr
    A data field that contains unique values used to identify items.

  • displayExpr
    A data field whose values should be displayed in the drop-down list.

When a user selects an item, the Lookup component saves the corresponding value from the valueExpr data field in the value property. You can also specify the value property in code to preselect an item as shown in the Simple Lookup use case.

Group Data

You can group data items in the drop-down list.

If the data source contains ungrouped data items, use the DataSource's group property to specify the data field to group by.

The Lookup component can also work with initially grouped data items. In this case, the data array should contain objects with the key and items fields:

let dataSource = [{
    key: "Group 1", // Group caption 
    items: [ // Items in Group 1
        { /* ... */ },
        { /* ... */ }
    ]
}, {
    key: "Group 2",
    items: [
        { /* ... */ },
        { /* ... */ }
    ]
}];

If data objects are grouped but use other field names, implement the DataSource's map function to create key and items field mappings.

NOTE

Only one-level grouping is supported.

Regardless of the data source structure, enable the grouped property.

Configure the Drop-Down List

The Lookup component uses the Popover component as a drop-down list. To customize the Popover, use the dropDownOptions property. It accepts an object with Popover properties. Alternatively, you can set the usePopover property to false to display lookup items in a pop-up window.