我有三个模型 - User, Membership, Connection，它们看起来像这样：
class User < ActiveRecord::Base
has_many :memberships, dependent: :destroy
end
class Membership < ActiveRecord::Base
belongs_to :inviter, class_name: "User", foreign_key: "user_id"
belongs_to :invited, class_name: "User", foreign_key: "invited_id"
has_many :connections, dependent: :destroy
end
class Connection < ActiveRecord::Base
belongs_to :inviter_membership, class_name: "Membership", foreign_key: "membership_id"
belongs_to :invited_membership, class_name: "Membership", foreign_key: "invited_membership_id"
end
但是......我想要做的是设置从user到connections的直接连接。所以，理想情况下，我希望能够user.invited_connections或user.inviter_connections，并且它们会对应正确的连接。
即。 user.invited_connections将对应membership.user_id == current_user.id的连接（但请记住，它是与该user_id关联的与该成员资格记录关联的连接...而不仅仅是与user_id相关联的成员资格package features.dataManagement.entity.table.ui;
import java.util.ArrayList;
import java.util.List;
import org.eclipse.jface.layout.TableColumnLayout;
import org.eclipse.jface.viewers.ColumnLabelProvider;
import org.eclipse.jface.viewers.ColumnWeightData;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredSelection;
import org.eclipse.jface.viewers.TableViewer;
import org.eclipse.jface.viewers.TableViewerColumn;
import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionAdapter;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Table;
import org.eclipse.swt.widgets.TableColumn;
import features.dataManagement.entity.table.edit.StringEditingSupport;
import features.dataManagement.entity.table.model.RowStringContentProvider;
import features.dataManagement.entity.table.model.RowStringModel;
public class CompositeTableViewer extends Composite
{
private TableViewer tableViewer;
private List<String> columnNames;
private List<RowStringModel> modelList;
private Button addButton;
public CompositeTableViewer(Composite parent, int style, List<String> columnNames, boolean rowAddable)
{
this(parent, style, SWT.MULTI | SWT.H_SCROLL | SWT.V_SCROLL | SWT.FULL_SELECTION | SWT.BORDER, columnNames, rowAddable);
}
public CompositeTableViewer(Composite parent, int style, int tableViewerStyle, List<String> columnNames, boolean rowAddable)
{
super(parent, style);
modelList = new ArrayList<RowStringModel>();
this.columnNames = columnNames;
GridLayout layout = new GridLayout(3, false);
layout.marginWidth = 4;
this.setLayout(layout);
Composite tableComposite = new Composite(this, SWT.NONE);
// set 3 columns for the buttons
tableComposite.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true, 3, 1));
setTableViewer(new TableViewer(tableComposite, tableViewerStyle));
TableViewerColumn tableViewerColumn = createColumn(tableComposite, tableViewer, 0);
tableViewerColumn.setEditingSupport(new StringEditingSupport(tableViewer));
TableColumnLayout tableColumnLayout = new TableColumnLayout();
tableColumnLayout.setColumnData(tableViewerColumn.getColumn(), new ColumnWeightData(1, 100, true));
tableComposite.setLayout(tableColumnLayout);
tableViewer.setContentProvider(new RowStringContentProvider(tableViewer, modelList));
final Table table = tableViewer.getTable();
table.setLinesVisible(true);
createButtons(this, rowAddable);
}
/*
* this is specific to my project you can directly use a
* List<RowStringModel> modelList
*/
public void setInput(List<Object> dataList)
{
List<RowStringModel> dataStringList = new ArrayList<RowStringModel>();
for (Object str : dataList)
{
if (str instanceof String)
dataStringList.add(new RowStringModel((String) str));
}
modelList.addAll(dataStringList);
this.tableViewer.setInput(modelList);
}
/*
* this is specific to my project you can directly use a
* List<RowStringModel> modelList
*/
public List<Object> getInput()
{
List<Object> objectsInGui = new ArrayList<Object>();
for (RowStringModel rowStr : modelList)
{
objectsInGui.add(rowStr.getContent());
}
return objectsInGui;
}
public void addButtonEnable(boolean enabled)
{
this.addButton.setEnabled(enabled);
}
// create the columns for the table
private TableViewerColumn createColumn(final Composite parent, final TableViewer viewer, int colNumber)
{
TableViewerColumn col = createTableViewerColumn(this.columnNames.get(colNumber), colNumber);
col.setLabelProvider(new ColumnLabelProvider()
{
@Override
public String getText(Object element)
{
RowStringModel rsm = (RowStringModel) element;
return rsm.getContent();
}
/* slight difference for the actual lines */
@Override
public Color getBackground(final Object element)
{
if (element instanceof RowStringModel)
{
return new Color(Display.getDefault(), 245, 255, 250);
}
return super.getBackground(element);
}
});
return col;
}
private TableViewerColumn createTableViewerColumn(String title, final int colNumber)
{
final TableViewerColumn viewerColumn = new TableViewerColumn(tableViewer, SWT.NONE);
final TableColumn column = viewerColumn.getColumn();
column.setText(title);
column.setResizable(true);
column.setMoveable(true);
return viewerColumn;
}
/**
* Add the "Add" and "Delete" buttons
*
* @param parent
* the parent composite
*/
private void createButtons(Composite parent, boolean rowAddable)
{
// Create and configure the "Add" button
this.addButton = new Button(parent, SWT.PUSH | SWT.CENTER);
this.addButton.setText("Add");
GridData gridData = new GridData(GridData.HORIZONTAL_ALIGN_BEGINNING);
gridData.widthHint = 80;
gridData.horizontalSpan = 1;
this.addButton.setLayoutData(gridData);
this.addButton.setEnabled(rowAddable);
this.addButton.addSelectionListener(new SelectionAdapter()
{
public void widgetSelected(SelectionEvent e)
{
modelList.add(new RowStringModel(""));
tableViewer.refresh();
CompositeTableViewer.this.setFocus();
int selection = CompositeTableViewer.this.tableViewer.getTable().getItemCount();
CompositeTableViewer.this.tableViewer.setSelection(new StructuredSelection(tableViewer.getElementAt(selection - 1)), true);
}
});
// Create and configure the "Delete" button
Button delete = new Button(parent, SWT.PUSH | SWT.CENTER);
delete.setText("Delete");
gridData = new GridData(GridData.HORIZONTAL_ALIGN_BEGINNING);
gridData.widthHint = 80;
delete.setLayoutData(gridData);
delete.addSelectionListener(new SelectionAdapter()
{
// Remove the selection and refresh the view
public void widgetSelected(SelectionEvent e)
{
Object[] dataTable = (Object[]) ((IStructuredSelection) tableViewer.getSelection()).toArray();
if (dataTable != null)
{
for (Object data : dataTable)
{
modelList.remove(data);
}
tableViewer.refresh();
}
}
});
}
public TableViewer getTableViewer()
{
return tableViewer;
}
public void setTableViewer(TableViewer tableViewer)
{
this.tableViewer = tableViewer;
}
public List<String> getColumnNames()
{
return columnNames;
}
public void setColumnNames(List<String> columnNames)
{
this.columnNames = columnNames;
}
}
。
这可能吗？
答案 0 :(得分：2)
您可以尝试以下方式：
has_many :invited_connections, through: :memberships, source: :invited_membership
has_many :inviter_connections, through: :memberships, source: :inviter_membership
干杯！