angular - ngx正式：如何将onchange事件添加到json模式中数组类型内的每个字段

Question

我有一个要求，比如一个项目取决于数组类型字段配置中的其他项目。我正在动态地将更改事件添加到一个字段，但它没有添加。代码如下所示，当我在数组中一一添加时，我需要用当前检查先前输入的元素值并决定。

JSON模式：

    {
  
  "type": "object",
  "title": "Rules",
  
  "properties": {

    "LR": {
      "type": "array",
      "maxItems": 9,
      "title": "LR",
      "items": {
        "type": "object",
        "properties": {

          "PMR": {
            "type": "string",
            "title": "PMR",
            "pattern": "^(\\d{1,3})(\\.\\d{0,2})?$",
            "widget": {
              "formlyConfig": {
                "templateOptions": {
                  "maxLength":"3",
                  "pmrChange":"this.pmrChange($event, field)"
                }
              }
            }
          }
        }
      }

    }
  }
}

**Adding event:**

  extendFieldConfigs(): FormlyFieldConfig[] {
    
    this.fieldConfig.fieldGroup.map((field) => {
     
      const key = field.key ? field.key.toUpperCase() : null;
      if (!key) return;
      debugger;
      switch (key) {
        case "LR":
         

          field.fieldArray &&
            field.fieldArray.fieldGroup.map((fgrpItem) => {
              const childKey = fgrpItem.key ? fgrpItem.key.toUpperCase() : null;
              switch (childKey) {
                case "PMR": {
                  fgrpItem.templateOptions.change = Function(
                    "field",
                    "$event",
                    fgrpItem.templateOptions.pmrChange
                  ).bind(this);
                  
                  break;
                }
              }
            });

          break;
      }
    });

    return [this.fieldConfig];
  }

 pmrChange(a, b) {
    alert(a);
  }