Mixed (beta) - React Native SDK

New in version 10.5.0-beta.1.


This feature is currently in beta. While we encourage you to try out the feature and give feedback, please be aware the API may change.

The mixed data type is a realm property type that can hold any valid Realm data type except a collection. You can create collections (lists, sets, and dictionaries) of type mixed, but a mixed itself cannot be a collection. Properties using the mixed data type can also hold null values.


The mixed data type is indexable, but you can't use it as a primary key. Because null is a permitted value, you can't declare a Mixed property as optional.

To set a property of your object model as Mixed, set the property's type to "mixed".

const DogSchema = {
name: "Dog",
properties: {
name: "string",
birthDate: "mixed",

Create an object with a mixed value by running the realm.create() method within a write transaction.

realm.write(() => {
// create a Dog with a birthDate value of type string
realm.create("Dog", { name: "Euler", birthDate: "December 25th, 2017" });
// create a Dog with a birthDate value of type date
realm.create("Dog", {
name: "Blaise",
birthDate: new Date("August 17, 2020"),
// create a Dog with a birthDate value of type int
realm.create("Dog", {
name: "Euclid",
birthDate: 10152021,
// create a Dog with a birthDate value of type null
realm.create("Dog", {
name: "Pythagoras",
birthDate: null,

Query for objects with a mixed value by running the Collection.filtered() method and passing in a filter for a non-mixed field. You can then print the value of the mixed property or the entire object itself.

// To query for Blaise's birthDate, filter for his name to retrieve the realm object.
// Use dot notation to access the birthDate property.
let blaiseBirthDate = realm.objects("Dog").filtered(`name = 'Blaise'`)[0].birthDate;
console.log(`Blaise's birth date is ${blaiseBirthDate}`);
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On this page

  • Overview
  • Realm Object Models
  • Create an Object With a Mixed Value
  • Query for Objects with a Mixed Value