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Some models of door locks have specific requirements and constraints when it comes to setting PIN codes. It’s essential to be aware of these to ensure seamless functionality and security. The requirements can be fetched by making a Get Device or List Devices (or List Locks) request. Sample set of access code requirements: 
{
  "device": {
    "device_id": "00000000-0000-0000-0000-000000000000",
    "capabilities_supported": [
      "access_code",
      "lock"
    ],
    "properties": {
      "supported_code_lengths": [
        4,
        5,
        6,
        7,
        8
      ],
      "max_active_codes_supported": 250,
      "code_constraints": [
        {
          "constraint_type": "no_zeros"
        },
        {
          "constraint_type": "name_length",
          "min_length": 1,
          "max_length": 12
        }
      ],
      "supports_backup_access_code_pool": true
      ...
    },
    ...
  },
  ...
}
Request:
const device = await seam.devices.get({
  device_id: 'ed4bb795-f29f-43e5-bc0f-35f69f9141b5',
})

console.log(device)
console.log(device.properties.code_constraints)
Response:
{
  device_id: 'ed4bb795-f29f-43e5-bc0f-35f69f9141b5',
  device_type: 'nuki_lock',
  capabilities_supported: [ 'access_code', 'lock' ],
  properties: {
    locked: false,
    online: true,
    manufacturer: 'nuki',
    battery_level: 0.86,
    nuki_metadata: {
      device_id: '3',
      device_name: 'Office Lock',
      keypad_battery_critical: false
    },
    keypad_battery: { level: 1 },
    supported_code_lengths: [ 6 ],
    has_native_entry_events: true,
    name: 'Office Lock',
    model: { display_name: 'Lock', manufacturer_display_name: 'Nuki' },
    battery: { level: 0.86, status: 'full' },
    image_url: 'https://connect.getseam.com/assets/images/devices/nuki_smart_lock_3_pro_black.png',
    image_alt_text: 'Nuki Smart Lock 3.0 Pro Black, Front',
    code_constraints: [ [Object], [Object], [Object] ],
    supports_backup_access_code_pool: true
  },
  location: null,
  connected_account_id: 'cac74c00-443b-440f-820e-e2907277fd9f',
  workspace_id: '398d80b7-3f96-47c2-b85a-6f8ba21d07be',
  created_at: '2023-10-19T04:43:40.852Z',
  errors: [],
  warnings: [],
  is_managed: true
}
[
  { constraint_type: 'cannot_start_with_12' },
  { constraint_type: 'no_zeros' },
  { constraint_type: 'name_length', max_length: 20 }
]

​
Supported Code Lengths

This property is denoted as supported_code_lengths and contains an array of numbers. These numbers represent the various lengths (in terms of digits) allowed for a PIN code. For example, if the array contains [4, 6], it means the door lock can accept 4-digit or 6-digit PIN codes. Example Payload: 
"supported_code_lengths": [
    4,
    5,
    6,
    7,
    8
]

​
Maximum Set Codes

The property max_active_codes_supported indicates the total number of codes that can be simultaneously set on a door lock. For the door locks that accommodate native scheduling, this count will includes future scheduled codes that are set on the lock. Example Payload: 
"max_active_codes_supported": 250

​
PIN Code Constraints

The code_constraints property gives insight into various conditions or limitations that apply to PIN codes. Each constraint in the code_constraints array is an object with at least the constraint_type property. Example Payload: 
"code_constraints": [
    {
        "constraint_type": "no_zeros"
    },
    {
        "constraint_type": "name_length",
        "min_length": 1,
        "max_length": 12
    }
]
The constraint_type property can be one of the following:
Constraint TypeDescription
no_zeros0s cannot be used as digits in the pin code.
cannot_start_with_12The pin code cannot start with the sequence of digits 12.
no_triple_consecutive_intsNo more than 3 digits in a row can be consecutive or the same in the pin code.
cannot_specify_pin_codeA pin code cannot be specified - it has to be left empty and one will be generated by the lock provider.
pin_code_matches_existing_setIf a pin code is specified, it must match an existing set of pin codes used in the account (for example, pin code matches the code assigned to a user in the system).
start_date_in_futureFor time-bound codes, the start date has to be in the future.
no_ascending_or_descending_sequenceThe PIN code cannot be a purely ascending (for example, 1234) or descending (for example, 9876) sequence.
at_least_three_unique_digitsThe PIN code must contain at least three distinct digits (for example, 1122 is invalid; 1123 is valid).
no_all_same_digitsThe PIN code cannot consist entirely of the same repeated digit (for example, 1111 is invalid).
unique_first_four_digitsThe first four digits of the PIN code must all be distinct.
cannot_contain_089The PIN code cannot contain any of the digits 0, 8, or 9.
cannot_contain_0789The PIN code cannot contain any of the digits 0, 7, 8, or 9. Only digits 1–6 are permitted. This constraint applies to TTLock cylinder devices whose physical keypad only includes buttons numbered 1 through 6.
name_lengthThe name of the code has some restrictions on length. When the constraint_type is name_length, the constraint object has one or two additional properties called min_length and max_length to specify the length constraints.
name_must_be_uniqueThe name of the access code must be unique across all codes on the device.

​
TTLock Devices with Limited Keypads

Some TTLock devices—particularly certain cylinder lock models—have a physical keypad with buttons numbered 1 through 6 only (no 0, 7, 8, or 9 keys). When Seam detects this hardware configuration, it automatically applies the cannot_contain_0789 constraint to the device. If you check device.properties.code_constraints for one of these devices, you will see: 
{
  "code_constraints": [
    { "constraint_type": "cannot_contain_0789" },
    { "constraint_type": "cannot_contain_089" }
  ]
}
When generating access codes for these devices, Seam automatically ensures that only digits 1–6 are used. If you attempt to set a code that contains a digit outside this range (for example, 9821), the request will be rejected with a descriptive error message indicating which digits are not supported. Seam detects this constraint automatically from the device’s reported hardware capabilities—no manual configuration is required.