ASP.NET MVC Controls | ComponentOne
In This Topic
    CollectionView Class
    In This Topic
    File
    wijmo.js
    Module
    wijmo.collections
    Derived Classes
    PivotCollectionView, ODataCollectionView
    Implements
    IEditableCollectionView, IPagedCollectionView

    Class that implements the ICollectionView interface to expose data in regular JavaScript arrays.

    The CollectionView class implements the following interfaces:

    To use the CollectionView class, start by declaring it and passing a regular array as a data source. Then configure the view using the filter, sortDescriptions, groupDescriptions, and pageSize properties. Finally, access the view using the items property. For example:

    ```typescript import { CollectionView, SortDescription} from '@grapecity/wijmo';

    // create a CollectionView based on a data array let view = new CollectionView(dataArray);

    // sort items by amount in descending order let sortDesc = new SortDescription('amount', false); view.sortDescriptions.push(sortDesc);

    // show only items with amounts greater than 100 view.filter = (item) => { return item.amount > 100 };

    // show the sorted, filtered result on the console view.items.forEach((item, index) => { console.log(index + ': ' + item.name + ' ' + item.amount); }); ```

    The example below shows how you can use a CollectionView to provide sorted views of some raw data:

    {@sample Core/CollectionView/CreatingViews/Sorting/Overview Example}

    Constructor

    Properties

    Methods

    Events

    Constructor

    constructor

    constructor(sourceCollection?: any, options?: any): CollectionView
    

    Initializes a new instance of the CollectionView class.

    Parameters
    • sourceCollection: any
    Optional

    Array that serves as a source for this CollectionView.

    JavaScript object containing initialization data for the control.

    Returns
    CollectionView

    Properties

    calculatedFields

    Gets or sets an object where the keys represent calculated fields and the values are expressions (functions or strings).

    Calculated fields require proxies. To use them in IE11, you will need a polyfill such as this one: https://www.npmjs.com/package/proxy-polyfill.

    Calculated fields can be useful when dealing with external data. For example, you could add a per-capita income field (gnp/pop) or a profit field (revenue-expenses).

    Calculated fields are dynamic. If you change the fields used in the calculation, their values are updated automatically. They are also read-only. You may change the value of the properties used to calculate them, but you cannot directly edit the result.

    Unlike FlexGrid cellTemplates, calculated fields can be used for sorting, filtering, and grouping. They can also be used with charts and any other Wijmo controls.

    Calculated fields can be defined as functions that take a data item as an argument or as strings.

    For example, if your data looked like this:

    ```typescript // regular data item interface IDataItem { product: string, brand: string, unitPrice: number, qty: number, shipped: boolean } function getData(): IDataItem[] { return [ { product: 'Banana', brand: 'Chiquita', unitPrice: 45.95, qty: 12, discount: .08, shipped: true }, ... ] } ```

    You could add function-based calculated fields this way:

    ```typescript // add calculated properties to IDataItem interface ICalcDataItem extends IDataItem { fullName: string; allCaps: string; totalPrice: number, tax: number; }

    let cv = new CollectionView(getData(), { calculatedFields: { fullName: ($: ICalcDataItem) => [$.brand, $.product].join(' '), allCaps: ($: ICalcDataItem) => $.fullName.toUpperCase(), totalPrice: ($: ICalcDataItem) => ($.unitPrice * $.qty) * (1 - $.discount), tax: ($: ICalcDataItem) => $.totalPrice * 0.12 } }); ``` **Function-based calculated fields** are usually a better choice than string-based calculated fields because:

    1) They provide design-time error checking and command completion, 2) They run faster, and 3) They do not have any issues with content-security policy (CSP).

    Alternatively, you could add string-based calculated fields:

    ```typescript let cv = new CollectionView(getData(), { calculatedFields: { fullName: '[$.brand, $.product].join(" ")', allCaps: '$.fullNameStr.toUpperCase()', totalPrice: '($.unitPrice * $.qty) * (1 - $.discount)', tax: '$.totalPrice * 0.12' }); ``` String expressions may refer to the current item via the context variable '$', which contains the item's original and calculated values.

    **String-based calculated fields** have advantages over function-based calculated fields that may be important in some scenarios:

    1) They are slightly more concise, and 2) They can be stored as data and easily changed at run-time.

    Type
    any

    canAddNew

    Gets a value that indicates whether a new item can be added to the collection.

    Type
    boolean

    canCancelEdit

    Gets a value that indicates whether the collection view can discard pending changes and restore the original values of an edited object.

    Type
    boolean

    canChangePage

    Gets a value that indicates whether the pageIndex value can change.

    Type
    boolean

    canFilter

    Gets a value that indicates whether this view supports filtering via the filter property.

    This property does not affect the filters property, which are always applied.

    Type
    boolean

    canGroup

    Gets a value that indicates whether this view supports grouping via the groupDescriptions property.

    Type
    boolean

    canRemove

    Gets a value that indicates whether items can be removed from the collection.

    Type
    boolean

    canSort

    Gets a value that indicates whether this view supports sorting via the sortDescriptions property.

    Type
    boolean

    currentAddItem

    Gets the item that is being added during the current add transaction.

    Type
    T

    currentEditItem

    Gets the item that is being edited during the current edit transaction.

    Type
    T

    currentItem

    Gets or sets the current item in the view.

    Type
    T

    currentPosition

    Gets the ordinal position of the current item in the view.

    Type
    number

    filter

    Gets or sets a callback used to determine if an item is suitable for inclusion in the view.

    The callback should return true if the item passed in as a parameter should be included in the view.

    The default value for this property is **null**, which means the data is not filtered.

    Type
    IPredicate

    filters

    Gets an array of IPredicate functions used as filters on this CollectionView.

    To be included in the view, an item has to pass the predicate in the filter property as well as all predicates in the filters collection.

    Type
    ObservableArray

    getError

    Gets or sets a callback that determines whether a specific property of an item contains validation errors.

    The method takes as parameters a data item, the property being validated, and a parsing parameter that describes whether the data has already been parsed and applied to the data item (parsing == false), or whether the user was trying to edit the value and entered a value that could not be parsed into the data type expected (parsing == true).

    The method returns a string containing an error message, or null if no errors were detected.

    For example,

    ```typescript view = new CollectionView(data, { getError: (item: any, prop: string, parsing: boolean) => {

    // parsing failed, show message if (parsing) { if (prop == 'date') { return 'Please enter a valid date in the format "MM/dd/yyyy"'; } else if (prop == 'id') { return 'Please enter a positive number'; } }

    // check that stored (parsed) data is valid if (prop == 'date' && item.date < minDate) { return 'Please enter a date after ' + Globalize.formatDate(minDate, 'd'); } else if (prop == 'id' && item.id < 0) { return 'Please enter a positive number'; } } }); ```

    Type
    IGetError

    groupDescriptions

    Gets a collection of GroupDescription objects that describe how the items in the collection are grouped in the view.

    Type
    ObservableArray

    groups

    Gets an array of CollectionViewGroup objects that represents the top-level groups.

    Type
    CollectionViewGroup[]

    isAddingNew

    Gets a value that indicates whether an add transaction is in progress.

    Type
    boolean

    isEditingItem

    Gets a value that indicates whether an edit transaction is in progress.

    Type
    boolean

    isEmpty

    Gets a value that indicates whether this view contains no items.

    Type
    boolean

    isPageChanging

    Gets a value that indicates whether the page index is changing.

    Type
    boolean

    isUpdating

    Gets a value that indicates whether notifications are currently suspended (see beginUpdate and endUpdate).

    Type

    itemCount

    Gets the total number of items in the view taking paging into account.

    Type
    number

    items

    Gets items in the view.

    Type
    T[]

    itemsAdded

    Gets an ObservableArray containing the records that were added to the collection since trackChanges was enabled.

    Type
    ObservableArray

    itemsEdited

    Gets an ObservableArray containing the records that were edited in the collection since trackChanges was enabled.

    Type
    ObservableArray

    itemsRemoved

    Gets an ObservableArray containing the records that were removed from the collection since trackChanges was enabled.

    Type
    ObservableArray

    newItemCreator

    Gets or sets a function that creates new items for the collection.

    If the creator function is not supplied, the CollectionView will try to create an uninitialized item of the appropriate type.

    If the creator function is supplied, it should be a function that takes no parameters and returns an initialized object of the proper type for the collection.

    Type
    IItemCreator

    pageCount

    Gets the total number of pages.

    Type
    number

    pageIndex

    Gets the zero-based index of the current page.

    Type
    number

    pageSize

    Gets or sets the number of items to display on each page.

    The default value for this property is **zero**, which disables paging.

    Type
    number

    refreshOnEdit

    Gets or sets a value that determines whether the CollectionView should automatically refresh its results (by applying the sort, filter, and grouping operations) after items are edited.

    The default value for this property is **true**, which ensures the collection is always sorted, filtered, and grouped correctly after any edit operations.

    Set it to **false** if you want updates to be deferred when items are edited. In this case, the collection will not be refreshed until the sorting, filtering, and grouping criteria change or until the refresh method is called (Excel behavior).

    Type
    boolean

    sortComparer

    Gets or sets a function used to compare values when sorting.

    If provided, the sort comparer function should take as parameters two values of any type, and should return -1, 0, or +1 to indicate whether the first value is smaller than, equal to, or greater than the second. If the sort comparer returns null, the standard built-in comparer is used.

    This sortComparer property allows you to use custom comparison algorithms that in some cases result in sorting sequences that are more consistent with user's expectations than plain string comparisons.

    For example, see Dave Koele's Alphanum algorithm. It breaks up strings into chunks composed of strings or numbers, then sorts number chunks in value order and string chunks in ASCII order. Dave calls the result a "natural sorting order".

    The example below shows a typical use for the sortComparer property:

    ```typescript import { CollectionView, isString } from '@grapecity/wijmo';

    // create a CollectionView with a custom sort comparer const view = new CollectionView(data, { sortComparer: (a: any, b: any) => { return isString(a) && isString(b) ? alphanum(a, b) // use custom comparer for strings : null; // use default comparer for everything else } }); ```

    The example below shows how you can use an Intl.Collator to control the sort order:

    ```typescript import { CollectionView, isString } from '@grapecity/wijmo';

    // create a CollectionView that uses an Intl.Collator to sort const collator = window.Intl ? new Intl.Collator() : null; let view = new CollectionView(data, { sortComparer: (a, b) => { return isString(a) && isString(b) && collator ? collator.compare(a, b) // use collator for strings : null; // use default comparer for everything else } }); ```

    Type
    IComparer

    sortConverter

    Gets or sets a function used to convert values when sorting.

    If provided, the function should take as parameters a SortDescription, a data item, and a value to convert, and should return the converted value.

    This property provides a way to customize sorting. For example, the FlexGrid control uses it to sort mapped columns by display value instead of by raw value.

    For example, the code below causes a CollectionView to sort the 'country' property, which contains country code integers, using the corresponding country names:

    ```typescript const countries = 'US,Germany,UK,Japan,Italy,Greece'.split(','); view.sortConverter = (sd: SortDescription, item: any, value: any) => { return sd.property === 'countryMapped' ? countries[value]; // convert country id into name : value; } ```

    The next example combines two values so when sorting by country, the view will break ties by city:

    ```typescript view.sortConverter: (sd: SortDescription, item: any, value: any) => { if (sd.property == 'country') { value = item.country + '\t' + item.city; } return value; } ```

    Type
    ISortConverter

    sortDescriptions

    Gets an array of SortDescription objects that describe how the items in the collection are sorted in the view.

    Type
    ObservableArray

    sortNulls

    Gets or sets a value that determines how null values should be sorted.

    This property is set to **SortNulls.Last** by default, which causes null values to appear last on the sorted collection, regardless of sort direction. This is also the default behavior in Excel.

    Type
    SortNulls

    sourceCollection

    Gets or sets the underlying (unfiltered and unsorted) collection.

    Type
    any

    totalItemCount

    Gets the total number of items in the view before paging is applied.

    Type
    number

    trackChanges

    Gets or sets a value that determines whether the control should track changes to the data.

    The default value for this property is **false**, so the CollectionView does not keep track of which data items have changed.

    If you set this property to **true**, the CollectionView will keep track of changes to the data and will expose them through the itemsAdded, itemsRemoved, and itemsEdited collections.

    Tracking changes is useful in situations where you need to update the server after the user has confirmed that the modifications are valid.

    After committing or cancelling changes, use the clearChanges method to clear the itemsAdded, itemsRemoved, and itemsEdited collections.

    The CollectionView only tracks changes made when the proper CollectionView methods are used (editItem/commitEdit, addNew/commitNew, and remove). Changes made directly to the data are not tracked.

    Type
    boolean

    useStableSort

    Gets or sets whether to use a stable sort algorithm.

    Stable sorting algorithms maintain the relative order of records with equal keys. For example, consider a collection of objects with an "Amount" field. If you sort the collection by "Amount", a stable sort will keep the original order of records with the same Amount value.

    The default value for this property is **false**, which causes the CollectionView to use JavaScript's built-in sort method, which is fast and usually stable.

    Chrome provides stable sorting since version 70, and Firefox since version 3. As of ES2019, sort is **required** to be stable. In ECMAScript 1st edition through ES2018, it was allowed to be unstable.

    Setting the useStableSort property to true ensures stable sorts on all browsers (even IE 11), but increases sort times by 30% to 50%.

    Type
    boolean

    Methods

    addNew

    addNew(item?: T, commit?: boolean): T
    

    Adds a new item to the collection.

    Calling this methods without any parameters creates a new item, adds it to the collection, and defers refresh operations until the new item is committed using the commitNew method or canceled using the cancelNew method.

    The code below shows how the addNew method is typically used:

    ```typescript // create the new item, add it to the collection var newItem = view.addNew();

    // initialize the new item newItem.id = getFreshId(); newItem.name = 'New Customer';

    // commit the new item so the view can be refreshed view.commitNew(); ```

    You can also add new items by pushing them into the sourceCollection and then calling the refresh method. The main advantage of addNew is in user-interactive scenarios (like adding new items in a data grid), because it gives users the ability to cancel the add operation. It also prevents the new item from being sorted or filtered out of view until the transaction is committed.

    New items are empty objects by default, unless the colletion has calculatedFields, in which case the new items will have properties set to values that depend on their data types (empty strings for string properties, zero for numeric properties, and null for other data types).

    This behavior is convenient since in many cases the calculated fields depend on expressions that rely on strings not being null. But you can customize this behavior by setting the newItemCreator property to a function that creates the new items and initializes them in any way you want.

    Parameters
    • item: T
    Optional

    Item to be added to the collection (optional).

    Whether to commit the new item immediately.

    Returns
    T

    beginUpdate

    beginUpdate(): void
    

    Suspend refreshes until the next call to endUpdate.

    Returns
    void

    cancelEdit

    cancelEdit(): void
    

    Ends the current edit transaction and, if possible, restores the original value to the item.

    Returns
    void

    cancelNew

    cancelNew(): void
    

    Ends the current add transaction and discards the pending new item.

    Returns
    void

    clearChanges

    clearChanges(): void
    

    Clears all changes by removing all items in the itemsAdded, itemsRemoved, and itemsEdited collections.

    Call this method after committing changes to the server or after refreshing the data from the server.

    Returns
    void

    commitEdit

    commitEdit(): void
    

    Ends the current edit transaction and saves the pending changes.

    Returns
    void

    commitNew

    commitNew(): void
    

    Ends the current add transaction and saves the pending new item.

    Returns
    void

    contains

    contains(item: T): boolean
    

    Returns a value indicating whether a given item belongs to this view.

    Parameters
    • item: T

      Item to seek.

    Returns
    boolean

    deferUpdate

    deferUpdate(fn: Function, force?: boolean): void
    

    Executes a function within a beginUpdate/endUpdate block.

    The collection will not be refreshed until the function finishes.

    The deferUpdate method ensures endUpdate is called even if the update function throws an exception.

    Parameters
    • fn: Function

      Function to be executed without updates.

    • force: boolean Optional

      Whether to force a refresh when ending the update.

    Returns
    void

    editItem

    editItem(item: T): void
    

    Begins an edit transaction of the specified item.

    Parameters
    • item: T

      Item to be edited.

    Returns
    void

    endUpdate

    endUpdate(force?: boolean): void
    

    Resume refreshes suspended by a call to beginUpdate.

    Parameters
    • force: boolean Optional

      Whether to force a refresh when ending the update.

    Returns
    void

    getAggregate

    getAggregate(aggType: Aggregate, binding: string, currentPage?: boolean): void
    

    Calculates an aggregate value for the items in this collection.

    Parameters
    • aggType: Aggregate

      Type of aggregate to calculate.

    • binding: string

      Property to aggregate on.

    • currentPage: boolean Optional

      Whether to include only items on the current page.

    Returns
    void

    implementsInterface

    implementsInterface(interfaceName: string): boolean
    

    Returns true if this object supports a given interface.

    Parameters
    • interfaceName: string

      Name of the interface to look for.

    Returns
    boolean

    moveCurrentTo

    moveCurrentTo(item: T): boolean
    

    Sets the specified item to be the current item in the view.

    Parameters
    • item: T

      Item that will become current.

    Returns
    boolean

    moveCurrentToFirst

    moveCurrentToFirst(): boolean
    

    Sets the first item in the view as the current item.

    Returns
    boolean

    moveCurrentToLast

    moveCurrentToLast(): boolean
    

    Sets the last item in the view as the current item.

    Returns
    boolean

    moveCurrentToNext

    moveCurrentToNext(): boolean
    

    Sets the item after the current item in the view as the current item.

    Returns
    boolean

    moveCurrentToPosition

    moveCurrentToPosition(index: number): boolean
    

    Sets the item at the specified index in the view as the current item.

    Parameters
    • index: number

      Index of the item that will become current.

    Returns
    boolean

    moveCurrentToPrevious

    moveCurrentToPrevious(): boolean
    

    Sets the item before the current item in the view as the current item.

    Returns
    boolean

    moveToFirstPage

    moveToFirstPage(): boolean
    

    Sets the first page as the current page.

    Returns
    boolean

    moveToLastPage

    moveToLastPage(): boolean
    

    Sets the last page as the current page.

    Returns
    boolean

    moveToNextPage

    moveToNextPage(): boolean
    

    Moves to the page after the current page.

    Returns
    boolean

    moveToPage

    moveToPage(index: number): boolean
    

    Moves to the page at the specified index.

    Parameters
    • index: number

      Index of the page to move to.

    Returns
    boolean

    moveToPreviousPage

    moveToPreviousPage(): boolean
    

    Moves to the page before the current page.

    Returns
    boolean

    onCollectionChanged

    onCollectionChanged(e?: NotifyCollectionChangedEventArgs): void
    

    Raises the collectionChanged event.

    Parameters
    Returns
    void

    onCurrentChanged

    onCurrentChanged(e?: EventArgs): void
    

    Raises the currentChanged event.

    Parameters
    Returns
    void

    onCurrentChanging

    onCurrentChanging(e: CancelEventArgs): boolean
    

    Raises the currentChanging event.

    Parameters
    Returns
    boolean

    onPageChanged

    onPageChanged(e?: EventArgs): void
    

    Raises the pageChanged event.

    Parameters
    Returns
    void

    onPageChanging

    onPageChanging(e: PageChangingEventArgs): boolean
    

    Raises the pageChanging event.

    Parameters
    Returns
    boolean

    onSourceCollectionChanged

    onSourceCollectionChanged(e?: EventArgs): void
    

    Raises the sourceCollectionChanged event.

    Parameters
    Returns
    void

    onSourceCollectionChanging

    onSourceCollectionChanging(e: CancelEventArgs): boolean
    

    Raises the sourceCollectionChanging event.

    Parameters
    Returns
    boolean

    refresh

    refresh(): void
    

    Re-creates the view using the current sort, filter, and group parameters.

    Returns
    void

    remove

    remove(item: T): void
    

    Removes the specified item from the collection.

    Parameters
    • item: T

      Item to be removed from the collection.

    Returns
    void

    removeAt

    removeAt(index: number): void
    

    Removes the item at the specified index from the collection.

    Parameters
    • index: number

      Index of the item to be removed from the collection. The index is relative to the view, not to the source collection.

    Returns
    void

    Events

    collectionChanged

    Occurs when the collection changes.

    Arguments
    NotifyCollectionChangedEventArgs

    currentChanged

    Occurs after the current item changes.

    Arguments
    EventArgs

    currentChanging

    Occurs before the current item changes.

    Arguments
    CancelEventArgs

    pageChanged

    Occurs after the page index changes.

    Arguments
    EventArgs

    pageChanging

    Occurs before the page index changes.

    Arguments
    PageChangingEventArgs

    sourceCollectionChanged

    Occurs after the value of the sourceCollection property changes.

    Arguments
    EventArgs

    sourceCollectionChanging

    Occurs before the value of the sourceCollection property changes.

    Arguments
    CancelEventArgs