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Bytes and ByteSize

bytes are accepted as-is, bytearray is converted using bytes(v), and str is converted using v.encode().
Like bytes, but where the value is kept partially secret; see Secrets.
Converts a string representing a number of bytes with units (such as '1KB' or '11.5MiB') into an integer.
A function which returns a type that can be used to add constraints to bytes.

Arguments to conbytes

The following arguments are available when using the conbytes type function

  • min_length: int = None: minimum length of the byte string
  • max_length: int = None: maximum length of the byte string
  • strict: bool = False: controls type coercion

However, for the sake of improved integration with type checkers, we now discourage the use of conbytes and other function calls used to return constrained types. Instead, you can use pydantic.types.Strict and annotated_types.Len as annotations to achieve these constraints:

import annotated_types
from typing_extensions import Annotated

from pydantic import BaseModel, Strict

class MyModel(BaseModel):
    # Instead of `my_bytes: conbytes(strict=True, min_length=10, max_length=20)`, use:
    my_bytes: Annotated[bytes, Strict(), annotated_types.Len(10, 20)]

Using ByteSize

You can use the ByteSize data type to (case-insensitively) convert a string representation of a number of bytes into an integer, and also to print out human-readable strings representing a number of bytes.

In conformance with IEC 80000-13 Standard we interpret '1KB' to mean 1000 bytes, and '1KiB' to mean 1024 bytes. In general, including a middle 'i' will cause the unit to be interpreted as a power of 2, rather than a power of 10 (so, for example, '1 MB' is treated as 1_000_000 bytes, whereas '1 MiB' is treated as 1_048_576 bytes).


Note that 1b will be parsed as "1 byte" and not "1 bit".

from pydantic import BaseModel, ByteSize

class MyModel(BaseModel):
    size: ByteSize

#> 52000
print(MyModel(size='3000 KiB').size)
#> 3072000

m = MyModel(size='50 PB')
#> 44.4PiB
#> 50.0PB

#> 45474.73508864641