Angular 2如何动态设置选择选项？

Question

我有一个这样的数组：

export var EXPRESSIONCATALOG: ExpressionCatalogItem[] = [{
        "selector" : "arrivalDate",
        "selectorName": "Arrival date",
        "constraints": ["GreaterThan", "LessThan", "Equals", "NotEquals"],
        "valueType": "Date"
    },
    {
        "selector": "departureDate",
        "selectorName":"Departure Date",
        "constraints": ["GreaterThan", "LessThan", "Equals", "NotEquals"],
        "valueType": "Date",
    },

等等是html模板：

<div class="container">
    <div class="row" *ngFor="#expression of expressions;#expressionindex = index">
        <div class="col-xs-3">
            <select class="form-control" [ngModel]="expression.selectorName" >
                <!--(ngModelChange)="onChange(expressionindex, $event)"-->
                <option *ngFor="#c of catalog;#catalogindex = index" [value]="c.selectorName">
                    {{c.selectorName}}
                </option>
            </select>
        </div>
        <div class="col-xs-3">
            <select class="form-control">
                <option *ngFor="#constraint of catalog">
                    {{constraint.constraints}}
                </option>
            </select>
        </div>

        <!--<constraint></constraint>-->
    </div>


    <a class="btn btn-primary" (click)="newCondition()"><i class="glyphicon glyphicon-plus"></i></a>
</div>

如何通过数组中给出的约束动态设置第二个选择？现在它显示所有这些都与第一个选择器不匹配。