Question

I want to be able to render a Grid while the number of some extra columns are unknown until I’m in the onRender() method based on the type of a certain data.

I have this class

ActivityModel extends BaseDataModel {
  // defines all common setXXX and getXXX needed
}

my problem is that, coming back from the server side, the model carries also some extra fields which must be also rendered as columns within the Grid.

My question :
Is there a way to have a kind of Indexed fields within AcitivityModel to be able to do the following ? : focus on col.setId("{indexed}");

        List<ActivityParameterModel> parameters = folderModel.getParameters();
    for (ActivityParameterModel param : parameters) {
        ActivityParamType paramType = param.getParamType();
        col = new ColumnConfig();
        col.setHeader(param.getParamName());
        col.setWidth(2);
                    //
                    // the following line is what I'm expecting to do
        col.setId("{indexed}");
        switch (paramType) {
        case N:
            NumberField nf = new NumberField();
            nf.setPropertyEditorType(Integer.class);
            col.setEditor(new CellEditor(nf));
            break;
        case S:
            TextField<String> tf = new TextField<String>();
            col.setEditor(new CellEditor(tf));
            break;
        }
        config.add(col);

Answer 1

here’s what I did to come up with the situation :

I stored in DB the variable parameters, here’s the entity :

    @Entity
    @Table(name = "ACTIVITYPARAMETER")
    public class ActivityParameter implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@SequenceGenerator(name = "ACTIVITYPARAMETER_IDACTIVITYPARAMETER_GENERATOR",   sequenceName = "SN_ACTIVITYPARAMETER", 
    allocationSize = 1)
@GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "ACTIVITYPARAMETER_IDACTIVITYPARAMETER_GENERATOR")
@Column(name = "ID_ACTIVITYPARAMETER", unique = true, nullable = false)
private Long idActivityParameter;

@Column(nullable = false, length = 256)
private String paramName;

@Column(nullable = false, length = 256)
private String paramType;

// uni-directional many-to-one association to Activitysetting
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "ACTIVITYSETTING_ID", nullable = false)
private ActivitySetting activitySetting;

@Column(name = "PARAMORDER", nullable = false)
private Long order;

@Column(name = "PARAMMANDATORY", nullable = false, precision = 1)
@TypeConverter(name = "booleanToNumberConverter", dataType = BigDecimal.class, objectType = Boolean.class)
private boolean mandatory;

at creation time of the grid, I created the fixed columns then I made a loop to build the variable parameters using simply set(paramName,DEFAULT_VALUE) as following :

        // Extra Fields
    List<ActivityParameterModel> parameters = folderModel.getParameters();
    int index = 1;
    for (ActivityParameterModel param : parameters) {
        String columnId = "param" + (index++);
        col = new ColumnConfig(columnId, param.getParamName(), 90);
        NumberField nf = new NumberField();
        col.setEditor(new CellEditor(nf));
        ActivityParamType paramType = param.getParamType();
        switch (paramType) {
        case N:
            nf.setValidateOnBlur(true);
            break;
        }
        config.add(col);
    }

it creates the extra columns and at submit time, I restore the values by looping again over parameter list and calling the get(paramName) to restore the value.