Length Validators

Length validators check the size of strings, lists, and other collections.

Length validators support transforms when validating strings. Transforms are applied before measuring length.

length!

Checks that the value has exactly the specified length.

generate_code:
  output:
    length!: 6

Parameter	Type	Description
value	integer	Exact required length

Examples

# Exact code length
generate_pin:
  output:
    length!: 4

# Fixed-length ID
create_id:
  output:
    length!: 36  # UUID length

# Specific list size
get_top_results:
  output:
    length!: 5

min_length!

Checks that the value has at least the specified length.

output:
  min_length!: 10

Parameter	Type	Description
value	integer	Minimum required length

Examples

# Ensure substantive response
output:
  min_length!: 50

# Require at least one result
search_products:
  output:
    min_length!: 1

# Validate input length
validate_password:
  input:
    password:
      min_length!: 8

max_length!

Checks that the value has at most the specified length.

output:
  max_length!: 1000

Parameter	Type	Description
value	integer	Maximum allowed length

Examples

# Limit response length
output:
  max_length!: 500

# Limit results returned
search_products:
  output:
    max_length!: 10

# Username length limit
validate_username:
  input:
    username:
      max_length!: 32

Combining Length Validators

Length Range

output:
  min_length!: 50
  max_length!: 500

With Other Validators

output:
  not_null!: true
  type!: "string"
  min_length!: 10
  max_length!: 1000
  contains!: "result"

Common Patterns

Response Quality Checks

output:
  not_null!: true
  type!: "string"
  min_length!: 20   # Not too short
  max_length!: 2000 # Not too long

Array Size Validation

search_products:
  output:
    type!: "array"
    min_length!: 1
    max_length!: 50

recommend:
  output:
    length!: 3  # Exactly 3 recommendations

Code Generation

generate_pin:
  output:
    type!: "string"
    length!: 4
    pattern!: "\\d{4}"

generate_code:
  output:
    type!: "string"
    length!: 6
    pattern!: "[A-Z0-9]{6}"

Using Transforms

Transforms are applied before measuring length:

# Trim whitespace before checking length
output:
  min_length!:
    value: 10
    transform: trim

# Collapse whitespace then check length
output:
  max_length!:
    value: 100
    transform: [trim, collapse_whitespace]

Notes on Length Calculation

Strings: Length is the number of characters
Arrays: Length is the number of items
Objects: Length is the number of keys

# String length (characters)
output:  # "Hello" has length 5
  length!: 5

# Array length (items)
items:  # [1, 2, 3] has length 3
  length!: 3

# Object length (keys)
config:  # {"a": 1, "b": 2} has length 2
  length!: 2

Getting started

Core Concepts

Agents

Workflows

Human in the Loop

Evals

Deployment

Length Validators

length!

min_length!

max_length!

Combining Length Validators

Length Range

With Other Validators

Common Patterns

Response Quality Checks

Array Size Validation

Code Generation

Using Transforms

Notes on Length Calculation

​length!

​min_length!

​max_length!

​Combining Length Validators

​Length Range

​With Other Validators

​Common Patterns

​Response Quality Checks

​Array Size Validation

​Code Generation

​Using Transforms

​Notes on Length Calculation

length!

min_length!

max_length!

Combining Length Validators

Length Range

With Other Validators

Common Patterns

Response Quality Checks

Array Size Validation

Code Generation

Using Transforms

Notes on Length Calculation