---
title: "Built-in Data types"
description: "Data types exported by TypeSpec"
---
## TypeSpec
### `Array` {#Array}



```typespec
model Array<Element>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| Element | The type of the array elements |


#### Properties
None

### `Create` {#Create}

A copy of the input model `T` with only the properties that are visible during the
"Create" resource lifecycle phase.

This transformation is recursive, and will include only properties that have the
`Lifecycle.Create` visibility modifier.

If a `NameTemplate` is provided, the new model will be named according to the template.
The template uses the same syntax as the `@friendlyName` decorator.
```typespec
model Create<T, NameTemplate>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| T | The model to transform. |
| NameTemplate | The name template to use for the new model.<br /><br />* |

#### Examples

```typespec
model Dog {
  @visibility(Lifecycle.Read)
  id: int32;

  name: string;
}

// This model has only the `name` field.
model CreateDog is Create<Dog>;
```

#### Properties
None

### `CreateOrUpdate` {#CreateOrUpdate}

A copy of the input model `T` with only the properties that are visible during the
"Create" or "Update" resource lifecycle phases.

The "CreateOrUpdate" lifecycle phase is used by default for properties passed as parameters to operations
that can create _or_ update data, like HTTP PUT operations.

This transformation is recursive, and will include only properties that have the
`Lifecycle.Create` or `Lifecycle.Update` visibility modifier.

If a `NameTemplate` is provided, the new model will be named according to the template.
The template uses the same syntax as the `@friendlyName` decorator.
```typespec
model CreateOrUpdate<T, NameTemplate>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| T | The model to transform. |
| NameTemplate | The name template to use for the new model.<br /><br />* |

#### Examples

```typespec
model Dog {
  @visibility(Lifecycle.Read)
  id: int32;

  @visibility(Lifecycle.Create)
  immutableSecret: string;

  @visibility(Lifecycle.Create, Lifecycle.Update)
  secretName: string;

  name: string;
}

// This model will have the `immutableSecret`, `secretName`, and `name` fields, but not the `id` field.
model CreateOrUpdateDog is CreateOrUpdate<Dog>;
```

#### Properties
None

### `DefaultKeyVisibility` {#DefaultKeyVisibility}

Applies a visibility setting to a collection of properties.
```typespec
model DefaultKeyVisibility<Source, Visibility>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| Source | An object whose properties are spread. |
| Visibility | The visibility to apply to all properties. |


#### Properties
None

### `Delete` {#Delete}

A copy of the input model `T` with only the properties that are visible during the
"Delete" resource lifecycle phase.

The "Delete" lifecycle phase is used for properties passed as parameters to operations
that delete data, like HTTP DELETE operations.

This transformation is recursive, and will include only properties that have the
`Lifecycle.Delete` visibility modifier.

If a `NameTemplate` is provided, the new model will be named according to the template.
The template uses the same syntax as the `@friendlyName` decorator.
```typespec
model Delete<T, NameTemplate>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| T | The model to transform. |
| NameTemplate | The name template to use for the new model.<br /><br />* |

#### Examples

```typespec
model Dog {
  @visibility(Lifecycle.Read)
  id: int32;

  // Set when the Dog is removed from our data store. This happens when the
  // Dog is re-homed to a new owner.
  @visibility(Lifecycle.Delete)
  nextOwner: string;

  name: string;
}

// This model will have the `nextOwner` and `name` fields, but not the `id` field.
model DeleteDog is Delete<Dog>;
```

#### Properties
None

### `DiscriminatedOptions` {#DiscriminatedOptions}

Options for `@discriminated` decorator.
```typespec
model DiscriminatedOptions
```


#### Properties
| Name | Type | Description |
|------|------|-------------|
| envelope? | `"object" \| "none"` | How is the discriminated union serialized. |
| discriminatorPropertyName? | [`string`](#string) | Name of the discriminator property |
| envelopePropertyName? | [`string`](#string) | Name of the property envelopping the data |

### `ExampleOptions` {#ExampleOptions}

Options for example decorators
```typespec
model ExampleOptions
```


#### Properties
| Name | Type | Description |
|------|------|-------------|
| title? | [`string`](#string) | The title of the example |
| description? | [`string`](#string) | Description of the example |

### `OmitDefaults` {#OmitDefaults}

Represents a collection of properties with default values omitted.
```typespec
model OmitDefaults<Source>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| Source | An object whose spread property defaults are all omitted. |


#### Properties
None

### `OmitProperties` {#OmitProperties}

Represents a collection of omitted properties.
```typespec
model OmitProperties<Source, Keys>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| Source | An object whose properties are spread. |
| Keys | The property keys to omit. |


#### Properties
None

### `OperationExample` {#OperationExample}

Operation example configuration.
```typespec
model OperationExample
```


#### Properties
| Name | Type | Description |
|------|------|-------------|
| parameters? | `unknown` | Example request body. |
| returnType? | `unknown` | Example response body. |

### `OptionalProperties` {#OptionalProperties}

Represents a collection of optional properties.
```typespec
model OptionalProperties<Source>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| Source | An object whose spread properties are all optional. |


#### Properties
None

### `PickProperties` {#PickProperties}

Represents a collection of properties with only the specified keys included.
```typespec
model PickProperties<Source, Keys>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| Source | An object whose properties are spread. |
| Keys | The property keys to include. |


#### Properties
None

### `Query` {#Query}

A copy of the input model `T` with only the properties that are visible during the
"Query" resource lifecycle phase.

The "Query" lifecycle phase is used for properties passed as parameters to operations
that read data, like HTTP GET or HEAD operations. This should not be confused for
the `@query` decorator, which specifies that the property is transmitted in the
query string of an HTTP request.

This transformation is recursive, and will include only properties that have the
`Lifecycle.Query` visibility modifier.

If a `NameTemplate` is provided, the new model will be named according to the template.
The template uses the same syntax as the `@friendlyName` decorator.
```typespec
model Query<T, NameTemplate>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| T | The model to transform. |
| NameTemplate | The name template to use for the new model.<br /><br />* |

#### Examples

```typespec
model Dog {
  @visibility(Lifecycle.Read)
  id: int32;

  // When getting information for a Dog, you can set this field to true to include
  // some extra information about the Dog's pedigree that is normally not returned.
  // Alternatively, you could just use a separate option parameter to get this
  // information.
  @visibility(Lifecycle.Query)
  includePedigree?: boolean;

  name: string;

  // Only included if `includePedigree` is set to true in the request.
  @visibility(Lifecycle.Read)
  pedigree?: string;
}

// This model will have the `includePedigree` and `name` fields, but not `id` or `pedigree`.
model QueryDog is Query<Dog>;
```

#### Properties
None

### `Read` {#Read}

A copy of the input model `T` with only the properties that are visible during the
"Read" resource lifecycle phase.

The "Read" lifecycle phase is used for properties returned by operations that read data, like
HTTP GET operations.

This transformation is recursive, and will include only properties that have the
`Lifecycle.Read` visibility modifier.

If a `NameTemplate` is provided, the new model will be named according to the template.
The template uses the same syntax as the `@friendlyName` decorator.
```typespec
model Read<T, NameTemplate>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| T | The model to transform. |
| NameTemplate | The name template to use for the new model.<br /><br />* |

#### Examples

```typespec
model Dog {
  @visibility(Lifecycle.Read)
  id: int32;

  @visibility(Lifecycle.Create, Lifecycle.Update)
  secretName: string;

  name: string;
}

// This model has the `id` and `name` fields, but not `secretName`.
model ReadDog is Read<Dog>;
```

#### Properties
None

### `Record` {#Record}



```typespec
model Record<Element>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| Element | The type of the properties |


#### Properties
None

### `ServiceOptions` {#ServiceOptions}

Service options.
```typespec
model ServiceOptions
```


#### Properties
| Name | Type | Description |
|------|------|-------------|
| title? | [`string`](#string) | Title of the service. |

### `Update` {#Update}

A copy of the input model `T` with only the properties that are visible during the
"Update" resource lifecycle phase.

The "Update" lifecycle phase is used for properties passed as parameters to operations
that update data, like HTTP PATCH operations.

This transformation will include only the properties that have the `Lifecycle.Update`
visibility modifier, and the types of all properties will be replaced with the
equivalent `CreateOrUpdate` transformation.

If a `NameTemplate` is provided, the new model will be named according to the template.
The template uses the same syntax as the `@friendlyName` decorator.
```typespec
model Update<T, NameTemplate>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| T | The model to transform. |
| NameTemplate | The name template to use for the new model.<br /><br />* |

#### Examples

```typespec
model Dog {
  @visibility(Lifecycle.Read)
  id: int32;

  @visibility(Lifecycle.Create, Lifecycle.Update)
  secretName: string;

  name: string;
}

// This model will have the `secretName` and `name` fields, but not the `id` field.
model UpdateDog is Update<Dog>;
```

#### Properties
None

### `UpdateableProperties` {#UpdateableProperties}

Represents a collection of updateable properties.
```typespec
model UpdateableProperties<Source>
```

#### Template Parameters
| Name | Description |
|------|-------------|
| Source | An object whose spread properties are all updateable. |


#### Properties
None

### `VisibilityFilter` {#VisibilityFilter}

A visibility filter, used to specify which properties should be included when
using the `withVisibilityFilter` decorator.

The filter matches any property with ALL of the following:
- If the `any` key is present, the property must have at least one of the specified visibilities.
- If the `all` key is present, the property must have all of the specified visibilities.
- If the `none` key is present, the property must have none of the specified visibilities.
```typespec
model VisibilityFilter
```


#### Properties
| Name | Type | Description |
|------|------|-------------|
| any? | `EnumMember[]` |  |
| all? | `EnumMember[]` |  |
| none? | `EnumMember[]` |  |

### `ArrayEncoding` {#ArrayEncoding}

Encoding for serializing arrays
```typespec
enum ArrayEncoding
```

| Name | Value | Description |
|------|-------|-------------|
| pipeDelimited |  | Each values of the array is separated by a \| |
| spaceDelimited |  | Each values of the array is separated by a <space> |


### `BytesKnownEncoding` {#BytesKnownEncoding}

Known encoding to use on bytes
```typespec
enum BytesKnownEncoding
```

| Name | Value | Description |
|------|-------|-------------|
| base64 | `"base64"` | Encode to Base64 |
| base64url | `"base64url"` | Encode to Base64 Url |


### `DateTimeKnownEncoding` {#DateTimeKnownEncoding}

Known encoding to use on utcDateTime or offsetDateTime
```typespec
enum DateTimeKnownEncoding
```

| Name | Value | Description |
|------|-------|-------------|
| rfc3339 | `"rfc3339"` | RFC 3339 standard. https://www.ietf.org/rfc/rfc3339.txt<br />Encode to string. |
| rfc7231 | `"rfc7231"` | RFC 7231 standard. https://www.ietf.org/rfc/rfc7231.txt<br />Encode to string. |
| unixTimestamp | `"unixTimestamp"` | Encode a datetime to a unix timestamp.<br />Unix timestamps are represented as an integer number of seconds since the Unix epoch and usually encoded as an int32. |


### `DurationKnownEncoding` {#DurationKnownEncoding}

Known encoding to use on duration
```typespec
enum DurationKnownEncoding
```

| Name | Value | Description |
|------|-------|-------------|
| ISO8601 | `"ISO8601"` | ISO8601 duration |
| seconds | `"seconds"` | Encode to integer or float as seconds |
| milliseconds | `"milliseconds"` | Encode to integer or float as milliseconds |


### `Lifecycle` {#Lifecycle}

A visibility class for resource lifecycle phases.

These visibilities control whether a property is visible during the various phases of a resource's lifecycle.
```typespec
enum Lifecycle
```

| Name | Value | Description |
|------|-------|-------------|
| Create |  | The property is visible when a resource is being created. |
| Read |  | The property is visible when a resource is being read. |
| Update |  | The property is visible when a resource is being updated. |
| Delete |  | The property is visible when a resource is being deleted. |
| Query |  | The property is visible when a resource is being queried.<br /><br />In HTTP APIs, this visibility applies to parameters of GET or HEAD operations. |
#### Examples

```typespec
model Dog {
 @visibility(Lifecycle.Read)
 id: int32;

 @visibility(Lifecycle.Create, Lifecycle.Update)
 secretName: string;

 name: string;
}
```

In this example, the `id` property is only visible during the read phase, and the `secretName` property is only visible
during the create and update phases. This means that the server will return the `id` property when returning a `Dog`,
but the client will not be able to set or update it. In contrast, the `secretName` property can be set when creating
or updating a `Dog`, but the server will never return it. The `name` property has no visibility modifiers and is
therefore visible in all phases.


### `boolean` {#boolean}

Boolean with `true` and `false` values.
```typespec
scalar boolean
```



### `bytes` {#bytes}

Represent a byte array
```typespec
scalar bytes
```



### `decimal` {#decimal}

A decimal number with any length and precision. This represent any `decimal` value possible.
It is commonly represented as `BigDecimal` in some languages.
```typespec
scalar decimal
```



### `decimal128` {#decimal128}

A 128-bit decimal number.
```typespec
scalar decimal128
```



### `duration` {#duration}

A duration/time period. e.g 5s, 10h
```typespec
scalar duration
```



### `float` {#float}

A number with decimal value
```typespec
scalar float
```



### `float32` {#float32}

A 32 bit floating point number. (`±1.5 x 10^−45` to `±3.4 x 10^38`)
```typespec
scalar float32
```



### `float64` {#float64}

A 64 bit floating point number. (`±5.0 × 10^−324` to `±1.7 × 10^308`)
```typespec
scalar float64
```



### `int16` {#int16}

A 16-bit integer. (`-32,768` to `32,767`)
```typespec
scalar int16
```



### `int32` {#int32}

A 32-bit integer. (`-2,147,483,648` to `2,147,483,647`)
```typespec
scalar int32
```



### `int64` {#int64}

A 64-bit integer. (`-9,223,372,036,854,775,808` to `9,223,372,036,854,775,807`)
```typespec
scalar int64
```



### `int8` {#int8}

A 8-bit integer. (`-128` to `127`)
```typespec
scalar int8
```



### `integer` {#integer}

A whole number. This represent any `integer` value possible.
It is commonly represented as `BigInteger` in some languages.
```typespec
scalar integer
```



### `numeric` {#numeric}

A numeric type
```typespec
scalar numeric
```



### `offsetDateTime` {#offsetDateTime}

A date and time in a particular time zone, e.g. "April 10th at 3:00am in PST"
```typespec
scalar offsetDateTime
```



### `plainDate` {#plainDate}

A date on a calendar without a time zone, e.g. "April 10th"
```typespec
scalar plainDate
```



### `plainTime` {#plainTime}

A time on a clock without a time zone, e.g. "3:00 am"
```typespec
scalar plainTime
```



### `safeint` {#safeint}

An integer that can be serialized to JSON (`−9007199254740991 (−(2^53 − 1))` to `9007199254740991 (2^53 − 1)` )
```typespec
scalar safeint
```



### `string` {#string}

A sequence of textual characters.
```typespec
scalar string
```



### `uint16` {#uint16}

A 16-bit unsigned integer (`0` to `65,535`)
```typespec
scalar uint16
```



### `uint32` {#uint32}

A 32-bit unsigned integer (`0` to `4,294,967,295`)
```typespec
scalar uint32
```



### `uint64` {#uint64}

A 64-bit unsigned integer (`0` to `18,446,744,073,709,551,615`)
```typespec
scalar uint64
```



### `uint8` {#uint8}

A 8-bit unsigned integer (`0` to `255`)
```typespec
scalar uint8
```



### `unixTimestamp32` {#unixTimestamp32}

Represent a 32-bit unix timestamp datetime with 1s of granularity.
It measures time by the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970.
```typespec
scalar unixTimestamp32
```



### `url` {#url}

Represent a URL string as described by https://url.spec.whatwg.org/
```typespec
scalar url
```



### `utcDateTime` {#utcDateTime}

An instant in coordinated universal time (UTC)"
```typespec
scalar utcDateTime
```


