PrimeFaces DataTable 中的 filterMatchMode 是如何工作的？

Question

Primefaces Datatable 允许您使用属性 filterMatchMode 配置用于列的过滤类型。

不过，如果您使用 LazyDataModel，您必须实现自己的搜索方法，该方法根本不会接收该属性。此功能是否仅对普通 DataModel 有用？

Answer 1

目前，开箱即用的 LazyDataModel 不支持此功能，但您仍然可以轻松使用它。 blemasle postedprimefaces 论坛对应补丁，可惜开发者仍未回复。

如果你想使用非代码侵入的解决方案，你可以试试我的。

过滤器约束通过以下方式获得：

 /**
 * @param tableSearchExpr expression, starting from the view root,
 *        which identifies the datatable to retrieve information from
 * @return map, containing pairs of {@code <filtered field id, match mode>}.
 *         Filtered field id is evaluated from the 'filterBy' 
 *         attribute of the column in the following way:
 *         #{item.name} -> name
 *         #{item.category.name} -> category.name
 */
public Map<String, FilterMatchMode> getFiltersMatchMode(String tableSearchExpr) {
    FacesContext context = FacesContext.getCurrentInstance();
    Object component = context.getViewRoot().findComponent(tableSearchExpr);

    if (null == component) {
        throw new IllegalArgumentException(
                    "No component found for search expression: " 
                            + tableSearchExpr);
    }
    if (!(component instanceof DataTable)) {
        throw new IllegalArgumentException(
                    "Component is not a DataTable: " + tableSearchExpr);
    }

    DataTable table = (DataTable) component;
    Map<String, FilterMatchMode> constraints = 
            new HashMap<String, FilterMatchMode>(table.getColumns().size());

    for (UIColumn column : table.getColumns()) {
        ValueExpression filterExpression = 
                  column.getValueExpression("filterBy");
        if (null != filterExpression) {
            String filterExpressionString = filterExpression.
                                                   getExpressionString();
            //evaluating filtered field id
            String filteredField = filterExpressionString.substring(
                    filterExpressionString.indexOf('.') + 1,
                    filterExpressionString.indexOf('}'));

            FilterMatchMode matchMode = 
                  FilterMatchMode.fromUiParam(column.getFilterMatchMode());

            constraints.put(filteredField, matchMode);
        }
    }

    return constraints;
}

FilterMatchMode 在哪里：

public enum FilterMatchMode {

STARTS_WITH("startsWith"), ENDS_WITH("endsWith"), 
CONTAINS("contains"), EXACT("exact");

/**
 * Value of p:column's filterMatchMode attribute 
 *     which corresponds to this math mode
 */
private final String uiParam;

FilterMatchMode(String uiParam) {
    this.uiParam = uiParam;
}

/**
 * @param uiParam value of p:column's filterMatchMode attribute
 * @return MatchMode which corresponds to given UI parameter
 * @throws IllegalArgumentException if no MatchMode 
 *          is corresponding to given UI parameter
 */
public static FilterMatchMode fromUiParam(String uiParam) {
    for (FilterMatchMode matchMode : values()) {
        if (matchMode.uiParam.equals(uiParam)) {
            return matchMode;
        }
    }
    throw new IllegalArgumentException("No MatchMode found for " + uiParam);
}

}