> For the complete documentation index, see [llms.txt](https://docs.tonic.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.tonic.ai/app/api/quick-start-guide/tonic-api-generator-assignment/generator-api-reference/generator-api-ref-alphanumeric-string-key.md).

# Alphanumeric String Key (AlphaNumericPkGenerator)

The [Alphanumeric String Key](/app/generation/generators/generator-reference/alphanumeric-string-key.md) generator can be applied to primary key columns. It generates unique alphanumeric strings of the same length as the input.

For example, for the origin value ABC123, the output value is a six-character alphanumeric string such as D24N05.

## Link object structure <a href="#generator-api-alphanumeric-string-key-link-object" id="generator-api-alphanumeric-string-key-link-object"></a>

The Alphanumeric String Key generator can be self-consistent, but not consistent with another column. You cannot configure differential privacy.

The `metadata` object is populated from the [`BaseMetadata`](https://app.tonic.ai/apidocs/index.html#/models/BaseMetadata) object.

`preservePrefix` identifies a specific string that, when it occurs at the beginning of the source values, must be preserved in the destination values.

`numSuffixCharacters` identifies the number of characters at the end of each source value to preserve in the destination value.

`maskDigitsOnly` indicates whether to only mask the numeric characters.

```json
{
  "schema": "string",
  "table": "string",
  "column": "string",
  "path": "string",  //JSON fields only
  "dataType": "string",  //MongoDB, Amazon DynamoDB, and JSON fields only
  "metadata": {
    "presetId": "string",
    "generatorId": "AlphaNumericPkGenerator",
    "preservePrefix": "string",
    "numSuffixCharacters": integer,
    "maskDigitsOnly": boolean,
    "isConsistent": boolean,
    "encryptionProcessor": "x-on", //To use configured Structural data encryption
    "customValueProcessor": "string" //If custom value processor applied
  }
}
```

## Example replacement <a href="#generator-api-alphanumeric-string-key-replacement" id="generator-api-alphanumeric-string-key-replacement"></a>

The following example replacement configures a column to use the built-in generator preset for the Alphanumeric String Key generator.

When a source value starts with `test_`, the destination value also starts with `test_`.

The destination values do not preserve any of the ending characters from the source values.

The generator masks both alphabetical and numeric characters.

The generator is not consistent.

```json
{
  "name": "workclass",
  "schema": "public",
  "table": "employees",
  "links": [
    {
      "schema": "public",
      "table": "employees",
      "column": "workclass",
      "metadata": {
        "presetId": "AlphaNumericPkGenerator",
        "generatorId": "AlphaNumericPkGenerator",
        "preservePrefix": "test_",
        "numSuffixCharacters": 0,
        "maskDigitsOnly": false,
        "isConsistent": false
      }
    }
  ]
}
```


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