如何通过第二个嵌套数组过滤具有嵌套数组的对象？

Question

I have an object with a structure like below.

Object{
    Array [{
        property1: "",
        property2: "",
        innerArray: [{
            arrayProperty1
            arrayProperty2
          }]
    }]
}

What is the best by way to filter by innerArray.Property2? I have a list of filters I need to apply. The code below is how I'm currently attempting to apply the filters, however the list is not being altered at all.

    if(filterList)
    {
      // if this length is 0, don't include inventory in the filter
      let filterOnInventoryId = filterList.filter((item: any) => {
        return (item && item.Type === 'InventoryId');
      });


      let shouldFilterInventoryId = filterOnInventoryId && filterOnInventoryId.length > 0;
      let shouldFilterAppointmentType = filterOnAppointmentType && filterOnAppointmentType.length > 0;

      // find any inventoryIds that are part of the filter, else return an empty list
      let filteredListInventoryId = shouldFilterInventoryId ? filterOnInventoryId.filter((item: any) => 
      {
        var x = this.selectedDateAndAppointmentList.filter((dateModelAndAppointment: any) => 
        {
          return dateModelAndAppointment.appointmentList.filter((appointment: any) =>{
            item.InventoryTypeId == appointment.Inventory.InventoryTypeId;
          })
        })
        return x;
      }) : [];

    }

Answer 1

Nesting array filtering such as:

selectedDateAndAppointmentList.filter(dateModelAndAppointment =>
  dateModelAndAppointment.appointmentList.filter(...)
);

will not perform any filtering of the top array because Array.prototype.filter always returns an array and your code is thus filtering on the truthy-ness of [] , which is always truthy, and nothing gets filtered.

selectedDateAndAppointmentList.filter(dateModelAndAppointment =>
  dateModelAndAppointment.appointmentList.filter(...)
  // ^ will always return true because appointmentList.filter always returns an array
);

Here's what's happening:

 // no filtering is happening because inner // filter always returns a truthy value console.log( [{ values: ["a", "b"] }, { values: ["c", "d"] }].filter(item => item.values.filter(val => val === "a") ) ); 

Instead, you should use Array.prototype.some or Array.prototype.every which return a boolean and not an array and thus can be used as a filtering condition:

selectedDateAndAppointmentList.filter(dateModelAndAppointment => 
  dateModelAndAppointment.appointmentList.some(...)
  // ^ this will return a boolean based on a nested array condition
)

For example:

 // filtering now works because the inner filter // correctly returns a boolean value depending // on the filter condition console.log( [{ values: ["a", "b"] }, { values: ["c", "d"] }].filter(item => item.values.some(val => val === "a") ) );