Function prop

prop<TValue>(defaultFn: () => TValue): OptionalModelProp<TValue>
Defines a model property, with an optional function to generate a default value if the input snapshot / model creation data is null or undefined.

Example:
```
x: prop(() => 10) // an optional number, with a default value of 10
x: prop<number[]>(() => []) // an optional number array, with a default empty array
```
Type Parameters
- TValue
  Value type.
Parameters
- defaultFn: () => TValue
  Default value generator function.
Returns OptionalModelProp<TValue>
prop<TValue>(defaultValue: Exclude<TValue>): OptionalModelProp<TValue>
Defines a model property, with an optional default value if the input snapshot / model creation data is null or undefined. You should only use this with primitive values and never with object values (array, model, object, etc).

Example:
```
x: prop(10) // an optional number, with a default value of 10
```
Type Parameters
- TValue
  Value type.
Parameters
- defaultValue: Exclude<TValue>
  Default primitive value.
Returns OptionalModelProp<TValue>
prop<TValue>(): MaybeOptionalModelProp<TValue>
Defines a model property with no default value.

Example:
```
x: prop<number>() // a required number
x: prop<number | undefined>() // an optional number, which defaults to undefined
```
Type Parameters
- TValue
  Value type.
Returns MaybeOptionalModelProp<TValue>