typescript props as object or array

Hey guys, I have a select that can or not be a multi-select So my select props are

type SelectProps = {
  items: SelectItem[]
  selectedItem: SelectItem | SelectItem[]
  setSelectedItem: (arg: SelectItem | SelectItem[]) => void
  multiple?: boolean
}

type SelectProps = {
  items: SelectItem[]
  selectedItem: SelectItem | SelectItem[]
  setSelectedItem: (arg: SelectItem | SelectItem[]) => void
  multiple?: boolean
}

so I can take a SelectItem or an array of those my problem is in the `setSelectedItem when I call my component

<Select
            key={idx}
            items={filter.options}
            selectedItem={filter.selectedItems}
            setSelectedItem={filter.setSelectedItems}
          />

<Select
            key={idx}
            items={filter.options}
            selectedItem={filter.selectedItems}
            setSelectedItem={filter.setSelectedItems}
          />

I got the error

Type '(arg: SelectItem[]) => void' is not assignable to type '(arg: SelectItem | SelectItem[]) => void'.
  Types of parameters 'arg' and 'arg' are incompatible.
    Type 'SelectItem | SelectItem[]' is not assignable to type 'SelectItem[]'.
      Type 'SelectItem' is missing the following properties from type 'SelectItem[]': length, pop, push, concat, and 29 more.ts(2322)
Select.tsx(13, 3): The expected type comes from property 'setSelectedItem' which is declared here on type 'IntrinsicAttributes & SelectProps'

Type '(arg: SelectItem[]) => void' is not assignable to type '(arg: SelectItem | SelectItem[]) => void'.
  Types of parameters 'arg' and 'arg' are incompatible.
    Type 'SelectItem | SelectItem[]' is not assignable to type 'SelectItem[]'.
      Type 'SelectItem' is missing the following properties from type 'SelectItem[]': length, pop, push, concat, and 29 more.ts(2322)
Select.tsx(13, 3): The expected type comes from property 'setSelectedItem' which is declared here on type 'IntrinsicAttributes & SelectProps'

I understand that the problem is something to do with it either being an object or an array and so it has different properties How can I make it typesafe and satisfy both cases?

3 Replies

not_null.OP•3y ago

my filter in this case is of type

export type FilterType = {
  selectedItems: SelectItem[]
  setSelectedItems: (arg: SelectItem[]) => void
  options: SelectItem[]
}

export type FilterType = {
  selectedItems: SelectItem[]
  setSelectedItems: (arg: SelectItem[]) => void
  options: SelectItem[]
}

Unknown User•3y ago

Message Not Public

not_null.OP•3y ago

oh I didnt thought of that, then I can only pass the multiple on the one that has an array I mean, it doesnt even need to be a prop at this point I guess, whenever its an array of selected it will be multiple

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typescript props as object or array