In a GWT web app, I am using a DataGrid to manage elements from a database. I represent a list of elements as rows, the columns being editable fields of their characteristics (id, name, description). I am mostly using the EditTextCell class.
I now want to create a custom cell, for a column that has to represent a list of "tags" that can be attached to every element. From this cell, tags could be added, using a + button (that makes a drop-down menu appear or something), and deleted. Each tag should be a kind of button, or interactive widget (I later want to display pop-up with info, trigger actions, etc).
Actually, it would not be so different from the "tags" bar on the Stack Overflow website...
So I have been looking for a solution:
I thought this would be easy to do. I imagined just putting a FlowPanel in the cell, adding/removing Buttons/Widgets dynamically. But it turns out that in GWT Widgets and Cells and very different objects apparently..
I read making use of the AbstractCell class to create a custom cell allows to do anything, but its working is very low level and obscure to me.
I saw that CompositeCell allows to combine various cell widgets into one cell, but I have not found if it is possible to do it dynamically, or if the widgets are going to be the same for all lines throughout a column. I mostly saw examples about, for instance, how to put two Buttons in every cell of a single column.
What is the easiest way to implement what I need?
EDIT:
So, after some tests, I am going for Andrei's suggestion and going "low-level", creating a custom cell extending AbstractCell<>. I could create an appropriate "render" function, that generates a list of html "button", and also attaches Javascript calls to my Java functions when triggering a Javascript event (onclick, onmouseover, onmouseout...).
It is working pretty well. For instance, by clicking the "+" button at the end a tag list, it calls a MenuBar widget that presents the list of tags that can be added.
But I am struggling to find a way to update the underlying data when adding a tag.
To sum up:
I have a CustomData class that represents the data I want to display in each line of the table. It also contains the list of tags as a Set.
ModelTable (extends DataGrid) is my table.
CustomCell (extends AbstractCell) can renders the list of tags as several buttons on a line.
A click on a "+" button in a cell makes a AddTagMenu popup drop down, from which I can click on the tag to add.
How do I update the content of the cell?
I tried playing around with onBrowserEvent, onEnterKeyDown, bus events... with no success. At best I can indeed add a tag element to the underlying object, but the table is not updated.
It's not possible to meet your requirements without going really "low-level", as you call it.
It's relatively easy to create a cell that would render tags exactly as you want them. Plus icon is also easy, if this is the only action on the cell. However, it is very difficult to make every tag within a cell an interactive widget, because the DataGrid will not let you attach handlers to HTML rendered within a cell. You will need to supply your own IDs to these widgets, and then attach handlers to them in your code. The problem, however, is that when the DataGrid refreshes/re-renders, your handlers will most likely be lost. So you will have to attach them again to every tag in every cell on every change in the DataGrid.
A much simpler approach is to create a composite widget that represents a "row", and then add these "rows" to a FlowPanel. You can easily make it look like a table with CSS, and supply your own widget that looks like a table header. You will need to recreate some of the functionality of the DataGrid, e.g. sorting when clicked on "column" header - if you need this functionality, of course.
As you have already noted, using CompositeCell could be a way to get what you want.
The idea is to create a cell for every tag and then (during rendering) decide which one should be shown (rendered). Finally combine all those cells into one by creating a CompositeCell.
The main disadvantage of this solution is that you need to know all possible tags before you create a DataGrid.
So, if you have a fixed list of possible tags or can get a list of all existing tags and this list is reasonably small, here is a solution.
First, we need to know which tag is represented by a column so I extended a Column class to keep information about a tag. Please, note that TagColumn uses ButtonCell and also handles update when the button is clicked:
public class TagColumn extends Column<DataType, String> {
private TagEnum tag;
public TagColumn(TagEnum tag) {
super(new ButtonCell());
this.tag = tag;
setFieldUpdater(new FieldUpdater<DataType, String>() {
#Override
public void update(int index, DataType object, String value) {
Window.alert("Tag " + getTag().getName() + " clicked");
}
});
}
public TagEnum getTag() {
return tag;
}
#Override
public String getValue(DataType object) {
return tag.getName();
}
}
Then create a cell for each tag (I have hard-coded all tags in a TagEnum):
List<HasCell<DataType, ?>> tagColumns = new ArrayList<HasCell<DataType, ?>>();
for(TagEnum tag : TagEnum.values())
tagColumns.add(new TagColumn(tag));
Now, the most important part: decide either to show the tag or not - overwrite render method of the CompositeCell:
CompositeCell<DataType> tagsCell = new CompositeCell<DataType>(tagColumns) {
#Override
protected <X> void render(Context context, DataType value, SafeHtmlBuilder sb, HasCell<DataType, X> hasCell) {
if(value.getTagList().contains(((TagColumn) hasCell).getTag()))
super.render(context, value, sb, hasCell);
else
sb.appendHtmlConstant("<span></span>");
}
};
This is important to always render any element (for example empty span when the tag should not be shown). Otherwise the CompositeCell's implemantation will get confused when accessing sibling elements.
Finally, full, working example code:
private DataGrid<DataType> getGrid() {
DataGrid<DataType> grid = new DataGrid<DataType>();
List<HasCell<DataType, ?>> tagColumns = new ArrayList<HasCell<DataType, ?>>();
for(TagEnum tag : TagEnum.values())
tagColumns.add(new TagColumn(tag));
CompositeCell<DataType> tagsCell = new CompositeCell<DataType>(tagColumns) {
#Override
protected <X> void render(Context context, DataType value, SafeHtmlBuilder sb, HasCell<DataType, X> hasCell) {
if(value.getTagList().contains(((TagColumn) hasCell).getTag()))
super.render(context, value, sb, hasCell);
else
sb.appendHtmlConstant("<span></span>");
}
};
Column<DataType, DataType> tagsColumn = new Column<DataType, DataType>(tagsCell) {
#Override
public DataType getValue(DataType object) {
return object;
}
};
grid.addColumn(tagsColumn, "Tags");
grid.setRowData(Arrays.asList(
new DataType(Arrays.asList(TagEnum.gwt)),
new DataType(Arrays.asList(TagEnum.table, TagEnum.datagrid)),
new DataType(Arrays.asList(TagEnum.datagrid, TagEnum.widget, TagEnum.customCell)),
new DataType(Arrays.asList(TagEnum.gwt, TagEnum.table, TagEnum.widget, TagEnum.customCell)),
new DataType(Arrays.asList(TagEnum.gwt, TagEnum.customCell)),
new DataType(Arrays.asList(TagEnum.gwt, TagEnum.table, TagEnum.datagrid, TagEnum.widget, TagEnum.customCell))
)
);
return grid;
}
public class TagColumn extends Column<DataType, String> {
private TagEnum tag;
public TagColumn(TagEnum tag) {
super(new ButtonCell());
this.tag = tag;
setFieldUpdater(new FieldUpdater<DataType, String>() {
#Override
public void update(int index, DataType object, String value) {
Window.alert("Tag " + getTag().getName() + " clicked");
}
});
}
public TagEnum getTag() {
return tag;
}
#Override
public String getValue(DataType object) {
return tag.getName();
}
}
public class DataType {
List<TagEnum> tagList;
public DataType(List<TagEnum> tagList) {
this.tagList = tagList;
}
public List<TagEnum> getTagList() {
return tagList;
}
}
public enum TagEnum {
gwt ("gwt"),
table ("table"),
datagrid ("datagrid"),
widget ("widget"),
customCell ("custom-cell");
private String name;
private TagEnum(String name) {
this.name = name;
}
public String getName() {
return name;
}
}
SWT Text has a method called setMessage which can be used with SWT.SEARCH to put an initial faded-out message in the text box.
Can something similar be done with SWT Combo? It seems it does not have the setMessage() method, so it seems like some other trick needs to be applied here.
You are right, the Combo does not have regular API to set a message like the text widget does.
You could try to use a PaintListener to draw the message text while the Combo text is empty.
combo.addPaintListener( new PaintListener() {
#Override
public void paintControl( PaintEvent event ) {
if( combo.getText().isEmpty() ) {
int x = ...; // indent some pixels
int y = ...; // center vertically
event.gc.drawText( "enter something", x, y );
}
}
} );
In addition, you would need several listeners that redraw the Combo after its native appearance was updated.
combo.addListener( SWT.Modify, event -> combo.redraw() );
A modify listener is certainly required to show/hide the message but there are probably more listeners necessary to redraw the message when it is invalidated. This answer may give further hints which events are necessary to capture: How to display a hint message in an SWT StyledText
Note, however, that drawing onto controls other than Canvas is unsupported and may not work on all platforms.
A simpler alternative to the paint listener that worked for my purposes involves programatically setting the text and text color using a FocusListener. Here is an example:
final String placeholder = "Placeholder";
combo.setForeground(Display.getDefault().getSystemColor(SWT.COLOR_GRAY));
combo.setText(placeholder);
combo.addFocusListener(new FocusListener() {
#Override
public void focusLost(FocusEvent e) {
String text = combo.getText();
if(text.isEmpty()) {
combo.setText(placeholder);
combo.setForeground(Display.getDefault().getSystemColor(SWT.COLOR_GRAY));
}
}
#Override
public void focusGained(FocusEvent e) {
String text = combo.getText();
if(text.equals(placeholder)) {
combo.setText("");
combo.setForeground(Display.getDefault().getSystemColor(SWT.COLOR_BLACK));
}
}
});
I am new with GWT_GXT
I use MVP(model-view-Presenter)
In Presenter, i call RPC to get data From database. After that i get a List data -> I set it for view
In view, code is below
#Override
public void setDeleteAllTest(List<DeleteAllTestModel> deleteAllTests) {
final ListStore<DeleteAllTestModel> listStore = new ListStore<DeleteAllTestModel>();
listStore.add(deleteAllTests);
gridView = new PMTGridDeleteAllTest<DeleteAllTestModel>().getPMTGridDeleteAllTest(listStore);
gridView.setAutoWidth(true);
}
#Override
protected void onRender(Element parent, int pos) {
super.onRender(parent, pos);
ContentPanel cp = new ContentPanel();
cp.setBodyBorder(false);
cp.setHeading("");
cp.setButtonAlign(Style.HorizontalAlignment.CENTER.CENTER);
cp.setLayout(new FitLayout());
cp.setSize(1200, 400);
cp.add(gridView);
verticalPanel.add(cp);
verticalPanel.add(nameField);
verticalPanel.add(cancelButton);
add(verticalPanel);
cancelButton.addSelectionListener(new SelectionListener<ButtonEvent>() {
#Override
public void componentSelected(ButtonEvent buttonEvent) {
PolicyDeleteAllTestDialog.this.hide();
}
});
getButtonById("ok").hide();
}
The Problem is that Gird is not refresh and update new data_ It only displays (the first Grid in the first Call) .. It always keep the first View( I use dialog to show grid)..
Help me!
Thanks
I don't exactly remember how it works and it really is what you need. But there is something like gridView.refresh();. I remember I sometime used to use grid.getView().refresh(true); but it's been a while. Also I think there is a concept named ListLoader that might be useful. I am not sure of myself but if I were you I would have a look at listLoader. I hope this will help you one way or another, sorry if it does not.
The problem is on the drawing by click or resizing browser. I have TabPanel placed with RowData, two TabItems with Chart (Google Vizualization) on one and Table with the same Data on the next. I create them on the page loading.
Then I click on Load Data (button) from DB, I redraw this two:
public void reDraw(final List<Double> slices, final String[] devices)
{
pcPie.draw(createTable(slices,devices),createOptions("По автомобилям"));
tPie.draw(createTable(slices, devices),CreateTableOptions());
}
That's work only for active TabItem and replace the drawing space from behind with this size (400px;200px) in generated HTML and I find that Data isn't changed at the behind section.
Also, when I resized the browser, Charts and Tables aren't resizing. I've tryed to use some of Layout, they don't work. May be I don't understand exactly how can use them correctly.
So,
How can I resize my Charts and Tables correct in the both of the
section (active and behind)?
How can I resize my Charts and Tables
on the browser resizing events?
Our first problem came from this: when you use the TabPanel component with some TabItems, behind TabItems aren't being created exactly, and you can not redraw them, cause object isn't created. So we change our code in activated section:
public void run() {
tpLineCharts.setBorders(true);
TabItem tiGraph = new TabItem("График");
tableData = createTable();
lcLines = new LineChart(tableData,
createOptions("По компании"));
lcLines.addSelectHandler(createSelectHandler(lcLines));
tiGraph.setLayout(new FitLayout());
tiGraph.add(lcLines);
tpLineCharts.add(tiGraph);
TabItem tiTable = new TabItem("Таблица");
tLine = new Table(tableData, CreateTableOptions());
tiTable.add(tLine);
tiTable.addListener(Events.Select, new Listener<BaseEvent>()
{
#Override
public void handleEvent(BaseEvent be) {
tLine.draw(tableData);
}
});
tpLineCharts.add(tiTable);
}}, CoreChart.PACKAGE, Table.PACKAGE);
where tableData - AbstractTableData. After this modification we can redraw our components:
public void reDrawLineChart(final ArrayList <Double> sumCompanyTraffic,
final ArrayList<Integer> axisName, String title)
{
tableData =createTable(sumCompanyTraffic, axisName);
tLine.draw(tableData, CreateTableOptions());
lcLines.draw(tableData, createOptions(title));
}
Also you need to add this options:
private Options createOptions(String title)
{
Options options = Options.create();
options.setTitleX("Период");
options.setTitle(title);
if(tpLineCharts.isRendered())
options.setSize(tpLineCharts.getWidth(true),
tpLineCharts.getHeight(true));
return options;
}
GWT's CellBrowser is a great way of presenting dynamic data.
However when the browser contains more rows than some (seemingly) arbitrary maximum, it offers a "Show More" label that the user can click to fetch the unseen rows.
How can I disable this behavior, and force it to always show every row?
There are several ways of getting rid of the "Show More" (which you can combine):
In your TreeViewModel, in your NodeInfo's setDisplay or in the DataProvider your give to the DefaultNodeInfo, in onRangeChange: overwrite the display's visible range to the size of your data.
Extend CellBrowser and override its createPager method to return null. It won't change the list's page size though, but you can set it to some very high value there too.
The below CellBrowser removes the "Show More" text plus loads all available elements without paging.
public class ShowAllElementsCellBrowser extends CellBrowser {
public ShowAllElementsCellBrowser(TreeViewModel viewModel, CellBrowser.Resources resources) {
super(viewModel, null, resources);
}
#Override
protected <C> Widget createPager(HasData<C> display) {
PageSizePager pager = new PageSizePager(Integer.MAX_VALUE);
// removes the text "Show More" during loading
display.setRowCount(0);
// increase the visible range so that no one ever needs to page
display.setVisibleRange(0, Integer.MAX_VALUE);
pager.setDisplay(display);
return pager;
}
}
I found a valid and simple solution in setting page size to the CellBrowser's builder.
Hope this will help.
CellBrowser.Builder<AClass> cellBuilder = new CellBrowser.Builder<AClass>(myModel, null);
cellBuilder.pageSize(Integer.MAX_VALUE);
cellBrowser = cellBuilder.build();
The easiest way to do this is by using the:
cellTree.setDefaultNodeSize(Integer.MAX_VALUE);
method on your Cell Tree. You must do this before you begin expanding the tree.
My workaround is to navigate through elements of treeview dom to get "show more" element with
public static List<Element> findElements(Element element) {
ArrayList<Element> result = new ArrayList<Element>();
findShowMore(result, element); return result; }
private static void findShowMore(ArrayList res, Element element) {
String c;
if (element == null) { return; }
if (element.getInnerText().equals("Show more")) { res.add(element);
}
for (int i = 0; i < DOM.getChildCount(element); i++) { Element
child = DOM.getChild(element, i); findShowMore(res, child); } }
and than use:
if (show) { element.getStyle().clearDisplay(); } else {
element.getStyle().setDisplay(Display.NONE); }