What is the best way to set up an empty constructor with a nested object?

Currently struggling with this issue in my code: I am unable to correctly initialize the nestedStudents property. Every attempt results in an error suggesting the object may be undefined.

export class StudentDto {
  students: number; 
  nestedStudents: {
    grades: number;
    classes: number;
  }

  constructor(
    props: {
        students?: number;
        nestedStudents?: {
          grades?: number
          classes?: number
        }
    } = {},
  ) {
    this.students = props.students || 0;
    //How should I properly initialize nestedStudents in this section?
  }
}

Answer №1

If you want to customize the students section, you can follow a similar approach to what you did with your statement, but instead of using 0, consider using the following code snippet:

  constructor(
    props: {
        students?: number;
        nestedStudents?: {
          grades?: number
          classes?: number
        }
    } = {},
  ) {
    this.students = props.students || 0;
    this.nestedStudents =  || {
        grades: 0, // default value
        classes: 0, // default value
        ...props.nestedStudent, // values provided in props will override defaults
        // ^ using `...(undefined)` is safe and won't cause any issues
    };
  }

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