# `createIdGenerator()`

Creates a customizable ID generator function. You can configure the alphabet, prefix, separator, and default size of the generated IDs.

```ts
import { createIdGenerator } from 'ai';

const generateCustomId = createIdGenerator({
  prefix: 'user',
  separator: '_',
});

const id = generateCustomId(); // Example: "user_1a2b3c4d5e6f7g8h"
```

## Import

<Snippet text={`import { createIdGenerator } from "ai"`} prompt={false} />

## API Signature

### Parameters

<PropertiesTable
  content={[
    {
      name: 'options',
      type: 'object',
      description:
        'Optional configuration object with the following properties:',
    },
    {
      name: 'options.alphabet',
      type: 'string',
      description:
        'The characters to use for generating the random part of the ID. Defaults to alphanumeric characters (0-9, A-Z, a-z).',
    },
    {
      name: 'options.prefix',
      type: 'string',
      description:
        'A string to prepend to all generated IDs. Defaults to none.',
    },
    {
      name: 'options.separator',
      type: 'string',
      description:
        'The character(s) to use between the prefix and the random part. Defaults to "-".',
    },
    {
      name: 'options.size',
      type: 'number',
      description:
        'The default length of the random part of the ID. Defaults to 16.',
    },
  ]}
/>

### Returns

Returns a function that generates IDs based on the configured options.

### Notes

- The generator uses non-secure random generation and should not be used for security-critical purposes.
- The separator character must not be part of the alphabet to ensure reliable prefix checking.

## Example

```ts
// Create a custom ID generator for user IDs
const generateUserId = createIdGenerator({
  prefix: 'user',
  separator: '_',
  size: 8,
});

// Generate IDs
const id1 = generateUserId(); // e.g., "user_1a2b3c4d"
```

## See also

- [`generateId()`](/docs/reference/ai-sdk-core/generate-id)


## Navigation

- [generateText](/docs/reference/ai-sdk-core/generate-text)
- [streamText](/docs/reference/ai-sdk-core/stream-text)
- [embed](/docs/reference/ai-sdk-core/embed)
- [embedMany](/docs/reference/ai-sdk-core/embed-many)
- [rerank](/docs/reference/ai-sdk-core/rerank)
- [generateImage](/docs/reference/ai-sdk-core/generate-image)
- [transcribe](/docs/reference/ai-sdk-core/transcribe)
- [generateSpeech](/docs/reference/ai-sdk-core/generate-speech)
- [experimental_generateVideo](/docs/reference/ai-sdk-core/generate-video)
- [Agent (Interface)](/docs/reference/ai-sdk-core/agent)
- [ToolLoopAgent](/docs/reference/ai-sdk-core/tool-loop-agent)
- [createAgentUIStream](/docs/reference/ai-sdk-core/create-agent-ui-stream)
- [createAgentUIStreamResponse](/docs/reference/ai-sdk-core/create-agent-ui-stream-response)
- [pipeAgentUIStreamToResponse](/docs/reference/ai-sdk-core/pipe-agent-ui-stream-to-response)
- [tool](/docs/reference/ai-sdk-core/tool)
- [dynamicTool](/docs/reference/ai-sdk-core/dynamic-tool)
- [createMCPClient](/docs/reference/ai-sdk-core/create-mcp-client)
- [Experimental_StdioMCPTransport](/docs/reference/ai-sdk-core/mcp-stdio-transport)
- [jsonSchema](/docs/reference/ai-sdk-core/json-schema)
- [zodSchema](/docs/reference/ai-sdk-core/zod-schema)
- [valibotSchema](/docs/reference/ai-sdk-core/valibot-schema)
- [Output](/docs/reference/ai-sdk-core/output)
- [ModelMessage](/docs/reference/ai-sdk-core/model-message)
- [UIMessage](/docs/reference/ai-sdk-core/ui-message)
- [validateUIMessages](/docs/reference/ai-sdk-core/validate-ui-messages)
- [safeValidateUIMessages](/docs/reference/ai-sdk-core/safe-validate-ui-messages)
- [createProviderRegistry](/docs/reference/ai-sdk-core/provider-registry)
- [customProvider](/docs/reference/ai-sdk-core/custom-provider)
- [cosineSimilarity](/docs/reference/ai-sdk-core/cosine-similarity)
- [wrapLanguageModel](/docs/reference/ai-sdk-core/wrap-language-model)
- [wrapImageModel](/docs/reference/ai-sdk-core/wrap-image-model)
- [LanguageModelV3Middleware](/docs/reference/ai-sdk-core/language-model-v2-middleware)
- [extractReasoningMiddleware](/docs/reference/ai-sdk-core/extract-reasoning-middleware)
- [simulateStreamingMiddleware](/docs/reference/ai-sdk-core/simulate-streaming-middleware)
- [defaultSettingsMiddleware](/docs/reference/ai-sdk-core/default-settings-middleware)
- [addToolInputExamplesMiddleware](/docs/reference/ai-sdk-core/add-tool-input-examples-middleware)
- [extractJsonMiddleware](/docs/reference/ai-sdk-core/extract-json-middleware)
- [stepCountIs](/docs/reference/ai-sdk-core/step-count-is)
- [hasToolCall](/docs/reference/ai-sdk-core/has-tool-call)
- [isLoopFinished](/docs/reference/ai-sdk-core/loop-finished)
- [simulateReadableStream](/docs/reference/ai-sdk-core/simulate-readable-stream)
- [smoothStream](/docs/reference/ai-sdk-core/smooth-stream)
- [generateId](/docs/reference/ai-sdk-core/generate-id)
- [createIdGenerator](/docs/reference/ai-sdk-core/create-id-generator)
- [DefaultGeneratedFile](/docs/reference/ai-sdk-core/default-generated-file)


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