Field array validation for not allowing duplicate values

Question

i have implemented a field array component using redux form. In my field array i have some validations for not containing for example letters in my inputs. My validation function is this:

const validateFieldArray = (values) => {
  const errors = {
    [LEGO_AMKA_ARRAY]: []
  };
  if (values.get(LEGO_AMKA_ARRAY)) {
    const amkas = values.get(LEGO_AMKA_ARRAY);
    amkas.forEach((field, index) => {
      const amkasErrors = {};
      const amkaField = field.get(AMKA_FIELD);
      if (!amkaField) {
        amkasErrors[AMKA_FIELD] = 'error.required';
        errors[LEGO_AMKA_ARRAY][index] = amkasErrors;
      } else if (onlyNumeric(amkaField) !== undefined) {
        amkasErrors[AMKA_FIELD] = 'error.numbers.allowed';
        errors[LEGO_AMKA_ARRAY][index] = amkasErrors;
      }
    });
  }
  return errors;
};

i want to add a validation for not allowing duplicate entries. If i enter a value which was entered in a previous field i must not allow this. How can i do this?

Thanks!

Answer 1

You can create a dictionary of each value and its occurrences in your array of values using reduce (note - you may need to use map before the reduce, i am not sure how your array structure looks like)

const dictOccurrences = values.get(LEGO_AMKA_ARRAY).reduce((acc, curr) => ({
    ...acc,
    [curr]: acc[curr] ? acc[curr] + 1 : 1,
}), {});

then inside your code:

const validateFieldArray = (values) => {
  const errors = {
    [LEGO_AMKA_ARRAY]: []
  };
  if (values.get(LEGO_AMKA_ARRAY)) {
    const amkas = values.get(LEGO_AMKA_ARRAY);
    const dictOccurrences = amkas.reduce((acc, curr) => ({
    ...acc,
    [curr]: acc[curr] ? acc[curr] + 1 : 1,
}), {});
    amkas.forEach((field, index) => {
      const amkasErrors = {};
      const amkaField = field.get(AMKA_FIELD);
      if (!amkaField) {
        amkasErrors[AMKA_FIELD] = 'error.required';
        errors[LEGO_AMKA_ARRAY][index] = amkasErrors;
      } else if (onlyNumeric(amkaField) !== undefined) {
        amkasErrors[AMKA_FIELD] = 'error.numbers.allowed';
      }
      if (dictOccurrences[amkaField] > 1) {
        amkasErrors[AMKA_FIELD] = 'error.duplicate';
      }
      errors[LEGO_AMKA_ARRAY][index] = amkasErrors;
    });
  }
  return errors;
};