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Data Types

All Convex documents are defined as Javascript objects. These objects can have field values of any of the types below.

You can codify the shape of documents within your tables by defining a schema.

Convex values

Convex supports the following types of values:

Convex TypeTS/JS Type
Example Usage
Validator for Argument Validation and Schemasjson Format for ExportNotes Document IDs.
Nullnullnullv.null()nullJavaScript's undefined is not a valid Convex value. Use null instead.
Int64bigint3nv.int64()string (base10)Int64s only support BigInts between -2^63 and 2^63-1. Convex supports bigints in most modern browsers.
Float64number3.1v.number()number / stringConvex supports all IEEE-754 double-precision floating point numbers (such as NaNs). Inf and NaN are JSON serialized as strings.
Stringstring"abc"v.string()stringStrings are stored as UTF-8 and must be valid Unicode sequences. Strings must be smaller than the 1MB total size limit when encoded as UTF-8.
BytesArrayBuffernew ArrayBuffer(8)v.bytes()string (base64)Convex supports first class bytestrings, passed in as ArrayBuffers. Bytestrings must be smaller than the 1MB total size limit for Convex types.
ArrayArray[1, 3.2, "abc"]v.array(values)arrayArrays can have at most 8192 values.
ObjectObject{a: "abc"}v.object({property: value})objectConvex only supports "plain old JavaScript objects" (objects that do not have a custom prototype). Convex includes all enumerable properties. Objects can have at most 1024 entries. Field names must be nonempty and not start with "$" or "_".

System fields

Every document in Convex has two automatically-generated system fields:

  • _id: The document ID of the document.
  • _creationTime: The time this document was created, in milliseconds since the Unix epoch.


Convex values must be less than 1MB in total size. This is an approximate limit for now, but if you're running into these limits and would like a more precise method to calculate a document's size, reach out to us. Documents can have nested values, either objects or arrays that contain other Convex types. Convex types can have at most 16 levels of nesting, and the cumulative size of a nested tree of values must be under the 1MB limit.

Table names may contain alphanumeric characters ("a" to "z", "A" to "Z", and "0" to "9") and underscores ("_"), and they cannot start with an underscore.

For information on other limits, see here.

If any of these limits don't work for you, let us know!

Working with dates and times

Convex does not have a special data type for working with dates and times. How you store dates depends on the needs of your application:

  1. If you only care about a point in time, you can store a UTC timestamp. We recommend following the _creationTime field example, which stores the timestamp as a number in milliseconds. In your functions and on the client you can create a JavaScript Date by passing the timestamp to its constructor: new Date(timeInMsSinceEpoch). You can then print the date and time in the desired time zone (such as your user's machine's configured time zone).
    • To get the current UTC timestamp in your function and store it in the database, use
  2. If you care about a calendar date or a specific clock time, such as when implementing a booking app, you should store the actual date and/or time as a string. If your app supports multiple timezones you should store the timezone as well. ISO8601 is a common format for storing dates and times together in a single string like "2024-03-21T14:37:15Z". If your users can choose a specific time zone you should probably store it in a separate string field, usually using the IANA time zone name (although you could concatenate the two fields with unique character like "|").

For more sophisticated printing (formatting) and manipulation of dates and times use one of the popular JavaScript libraries: date-fns, Day.js, Luxon or Moment.js.