问题
I'm trying to convert a cellTable into adatagrid, because I want to add a search handler later and therefor I need fixed column headers. At the moment I extend the celltable/datagrid class and put the widget into a simplelayoutpanel and add this to my tabpanel.
If I use the celltable, all works fine and the data shows up. If I change the type of the class to datagrid, the data shows sometimes up (The column names are always there). To add something to the table I used setRowData or a dataProvider. If I set breakpoints to delay the loading of the table content, the table does sometimes contain data. If I later call the redraw method for the table, the table shows the correct information. But the table should load automatically the content. At other "positions" of my project I used the datagrid also and it worked in Dialogboxes.
I think there must be a bug with the drawing of the items, because if I call .getRowCount on the table or the deprecated .getDisplayedItems, it returns me the correct number of items which should be in the table. Also if I add a selection model to the table and select a item, the item contains valid data.
回答1:
DataGrid requires to be put in a LayoutPanel or Panel that implements the ProvidesResize interface to be visible. ScrollPanel implements that interface.
Furthermore this chain of LayoutPanels from your DataGrid up to your root element/panel has to be unbroken. That seems to be the case in your panel hierarchy.
Finally you have to use the RootLayoutPanel instead of the RootPanel to add your LayoutPanels. So did you make sure that you add your SimpleLayoutPanel to the RootLayoutPanel ?
Also refer to this GWT: DataGrid - set height 100% not rendering properly
回答2:
Here are my 2 cents.
When it comes to render a DataGrid outside of a properly formed "LayoutPanel or Panel that implements the ProvidesResize" tree structure, I found out I always need to keep the following in mind:
As this question explains, the height DataGrid property needs an explicit value, for example, "123px". Without this, DataGrid does not show its data rows (even if they are in the DOM).
If put a DataGrid inside an unfocused DecoratedTabPanel tab, DataGrid.redraw() needs to be called when such tab gets focus . Again, without this, DataGrid does not show its data rows (even if they are in the DOM).
I hope this helps.
回答3:
In my case it was caused by this: DataGrid rows not visible in second tab of TabLayoutPanel
来源：https://stackoverflow.com/questions/12173108/gwt-datagrid-does-not-show-data-but-contains-it