Package jakarta.faces.component

Class UIData

  • All Implemented Interfaces:
    NamingContainer, PartialStateHolder, StateHolder, TransientStateHolder, UniqueIdVendor, ComponentSystemEventListener, FacesListener, SystemEventListenerHolder, EventListener
    Direct Known Subclasses:
    HtmlDataTable
    @JSFComponent(defaultRendererType="jakarta.faces.Table")
public class UIData
extends UIComponentBase
implements NamingContainer, UniqueIdVendor
    Represents an abstraction of a component which has multiple "rows" of data.

    The children of this component are expected to be UIColumn components.

    Note that the same set of child components are reused to implement each row of the table in turn during such phases as apply-request-values and render-response. Altering any of the members of these components therefore affects the attribute for every row, except for the following members:

    • submittedValue
    • value (where no EL binding is used)
    • valid

    This reuse of the child components also means that it is not possible to save a reference to a component during table processing, then access it later and expect it to still represent the same row of the table.

    Implementation Notes

    Each of the UIColumn children of this component has a few component children of its own to render the contents of the table cell. However there can be a very large number of rows in a table, so it isn't efficient for the UIColumn and all its child objects to be duplicated for each row in the table. Instead the "flyweight" pattern is used where a serialized state is held for each row. When setRowIndex is invoked, the UIColumn objects and their children serialize their current state then reinitialise themselves from the appropriate saved state. This allows a single set of real objects to represent multiple objects which have the same types but potentially different internal state. When a row is selected for the first time, its state is set to a clean "initial" state. Transient components (including any read-only component) do not save their state; they are just reinitialised as required. The state saved/restored when changing rows is not the complete component state, just the fields that are expected to vary between rows: "submittedValue", "value", "isValid".

    Note that a table is a "naming container", so that components within the table have their ids prefixed with the id of the table. Actually, when setRowIndex has been called on a table with id of "zzz" the table pretends to its children that its ID is "zzz_n" where n is the row index. This means that renderers for child components which call component.getClientId automatically get ids of form "zzz_n:childId" thus ensuring that components in different rows of the table get different ids.

    When decoding a submitted page, this class iterates over all its possible rowIndex values, restoring the appropriate serialized row state then calling processDecodes on the child components. Because the child components (or their renderers) use getClientId to get the request key to look for parameter data, and because this object pretends to have a different id per row ("zzz_n") a single child component can decode data from each table row in turn without being aware that it is within a table. The table's data model is updated before each call to child.processDecodes, so the child decode method can assume that the data model's rowData points to the model object associated with the row currently being decoded. Exactly the same process applies for the later validation and updateModel phases.

    When the data model for the table is bound to a backing bean property, and no validation errors have occured during processing of a postback, the data model is refetched at the start of the rendering phase (ie after the update model phase) so that the contents of the data model can be changed as a result of the latest form submission. Because the saved row state must correspond to the elements within the data model, the row state must be discarded whenever a new data model is fetched; not doing this would cause all sorts of inconsistency issues. This does imply that changing the state of any of the members "submittedValue", "value" or "valid" of a component within the table during the invokeApplication phase has no effect on the rendering of the table. When a validation error has occurred, a new DataModel is not fetched, and the saved state of the child components is not discarded.

    see Javadoc of the Faces Specification for more information.

    • Constructor Detail

      • UIData

        public UIData()
        Construct an instance of the UIData.

    • Method Detail

      • invokeOnComponent

        public boolean invokeOnComponent​(FacesContext context,
                                 String clientId,
                                 ContextCallback callback)
                          throws FacesException
        Description copied from class: UIComponentBase
        invokeOnComponent must be implemented in UIComponentBase too...
        Overrides:
        invokeOnComponent in class UIComponentBase
        Parameters:
        context - FacesContext for the current request
        clientId - the id of the desired UIComponent clazz
        callback - Implementation of the ContextCallback to be called
        Returns:
        has component been found ?
        Throws:
        FacesException

      • setFooter

        public void setFooter​(UIComponent footer)

      • setHeader

        public void setHeader​(UIComponent header)

      • isRowAvailable

        public boolean isRowAvailable()

      • getRowCount

        public int getRowCount()

      • getRowData

        public Object getRowData()

      • getRowIndex

        public int getRowIndex()

      • setRowIndex

        public void setRowIndex​(int rowIndex)
        Set the current row index that methods like getRowData use.

        Param rowIndex can be -1, meaning "no row".

        Parameters:
        rowIndex -

      • restoreState

        public void restoreState​(FacesContext context,
                         Object state)
        Description copied from class: UIComponentBase
        Invoked in the "restore view" phase, this initialises this object's members from the values saved previously into the provided state object.

        Specified by:
        restoreState in interface StateHolder
        Overrides:
        restoreState in class UIComponentBase
        state - is an object previously returned by the saveState method of this class.

      • saveState

        public Object saveState​(FacesContext context)
        Description copied from class: UIComponentBase
        Invoked after the render phase has completed, this method returns an object which can be passed to the restoreState of some other instance of UIComponentBase to reset that object's state to the same values as this object currently has.
        Specified by:
        saveState in interface StateHolder
        Overrides:
        saveState in class UIComponentBase

      • queueEvent

        public void queueEvent​(FacesEvent event)
        Modify events queued for any child components so that the UIData state will be correctly configured before the event's listeners are executed.

        Child components or their renderers may register events against those child components. When the listener for that event is eventually invoked, it may expect the uidata's rowData and rowIndex to be referring to the same object that caused the event to fire.

        The original queueEvent call against the child component has been forwarded up the chain of ancestors in the standard way, making it possible here to wrap the event in a new event whose source is this component, not the original one. When the event finally is executed, this component's broadcast method is invoked, which ensures that the UIData is set to be at the correct row before executing the original event.

        Overrides:
        queueEvent in class UIComponentBase

      • encodeBegin

        public void encodeBegin​(FacesContext context)
                 throws IOException
        Perform necessary actions when rendering of this component starts, before delegating to the inherited implementation which calls the associated renderer's encodeBegin method.
        Overrides:
        encodeBegin in class UIComponentBase
        Throws:
        IOException

      • processUpdates

        public void processUpdates​(FacesContext context)
        Description copied from class: UIComponentBase
        This isn't an input component, so just pass on the processUpdates call to child components and facets that might be input components.

        Components that were never rendered can't possibly be receiving update data (no corresponding fields were ever put into the response) so if this component is not rendered then this method does not invoke processUpdates on its children.

        Overrides:
        processUpdates in class UIComponentBase

      • getDataModel

        protected DataModel getDataModel()
        Return the datamodel for this table, potentially fetching the data from a backing bean via a value-binding if this is the first time this method has been called.

        This is complicated by the fact that this table may be nested within another table. In this case a different datamodel should be fetched for each row. When nested within a parent table, the parent reference won't change but parent.getContainerClientId() will, as the suffix changes depending upon the current row index. A map object on this component is therefore used to cache the datamodel for each row of the table. In the normal case where this table is not nested inside a component that changes its id (like a table does) then this map only ever has one entry.

      • setDataModel

        protected void setDataModel​(DataModel dataModel)

      • getValue

        @JSFProperty
public Object getValue()
        An EL expression that specifies the data model that backs this table.

        The value referenced by the EL expression can be of any type.

        • A value of type DataModel is used directly.
        • Array-like parameters of type array-of-Object, java.util.List or java.sql.ResultSet are wrapped in a corresponding DataModel that knows how to iterate over the elements.
        • Other values are wrapped in a DataModel as a single row.

        Note in particular that unordered collections, eg Set are not supported. Therefore if the value expression references such an object then the table will be considered to contain just one element - the collection itself.

      • setValue

        public void setValue​(Object value)

      • getFirst

        @JSFProperty
public int getFirst()
        Defines the index of the first row to be displayed, starting from 0.

      • setFirst

        public void setFirst​(int first)

      • getRows

        @JSFProperty
public int getRows()
        Defines the maximum number of rows of data to be displayed.

        Specify zero to display all rows from the "first" row to the end of available data.

      • setRows

        public void setRows​(int rows)
        Set the maximum number of rows displayed in the table.

      • getVar

        @JSFProperty(literalOnly=true)
public String getVar()
        Defines the name of the request-scope variable that will hold the current row during iteration.

        During rendering of child components of this UIData, the variable with this name can be read to learn what the "rowData" object for the row currently being rendered is.

        This value must be a static value, ie an EL expression is not permitted.

      • visitTree

        public boolean visitTree​(VisitContext context,
                         VisitCallback callback)
        Overrides the behavior in UIComponent.visitTree(jakarta.faces.component.visit.VisitContext, jakarta.faces.component.visit.VisitCallback) to handle iteration correctly.
        Overrides:
        visitTree in class UIComponentBase
        Parameters:
        context - the visit context which handles the processing details
        callback - the callback to be performed
        Returns:
        false if the processing is not done true if we can shortcut the visiting because we are done with everything
        Since:
        2.0

      • setVar

        public void setVar​(String var)

      • isRowStatePreserved

        @JSFProperty(literalOnly=true,
             faceletsOnly=true)
public boolean isRowStatePreserved()
        Indicates whether the state for a component in each row should not be discarded before the datatable is rendered again. This will only work reliable if the datamodel of the datatable did not change either by sorting, removing or adding rows. Default: false
        Returns:

      • setRowStatePreserved

        public void setRowStatePreserved​(boolean preserveComponentState)