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# ISBN

The `pydantic_extra_types.isbn` module provides functionality to receive and validate ISBN.

ISBN (International Standard Book Number) is a numeric commercial book identifier which is intended to be unique. This module provides an ISBN type for Pydantic models.

## ISBN

**Bases:** [`str`](https://docs.python.org/3/builtins/stdtypes.html#str)

Represents a ISBN and provides methods for conversion, validation, and serialization.

```py
from pydantic import BaseModel

from pydantic_extra_types.isbn import ISBN


class Book(BaseModel):
    isbn: ISBN


book = Book(isbn='8537809667')
print(book)
# > isbn='9788537809662'
```

### Methods

#### validate\_isbn\_format

`@staticmethod`

```python
def validate_isbn_format(value: str) -> None
```

Validate a ISBN format from the provided str value.

##### Returns

[`None`](https://docs.python.org/3/builtins/constants.html#None)

##### Parameters

**`value`** : [`str`](https://docs.python.org/3/builtins/stdtypes.html#str)

The str value representing the ISBN in 10 or 13 digits.

##### Raises

- `PydanticCustomError` -- If the ISBN is not valid.

#### convert\_isbn10\_to\_isbn13

`@staticmethod`

```python
def convert_isbn10_to_isbn13(value: str) -> str
```

Convert an ISBN-10 to ISBN-13.

##### Returns

[`str`](https://docs.python.org/3/builtins/stdtypes.html#str) -- The converted ISBN or the original value if no conversion is necessary.

##### Parameters

**`value`** : [`str`](https://docs.python.org/3/builtins/stdtypes.html#str)

The ISBN-10 value to be converted.

## isbn10\_digit\_calc

```python
def isbn10_digit_calc(isbn: str) -> str
```

Calculate the ISBN-10 check digit from the provided str value. More information on the validation algorithm on [Wikipedia](https://en.wikipedia.org/wiki/ISBN#Check_digits)

### Returns

[`str`](https://docs.python.org/3/builtins/stdtypes.html#str) -- The calculated last digit of the ISBN-10 value.

### Parameters

**`isbn`** : [`str`](https://docs.python.org/3/builtins/stdtypes.html#str)

The str value representing the ISBN in 10 digits.

## isbn13\_digit\_calc

```python
def isbn13_digit_calc(isbn: str) -> str
```

Calc a ISBN-13 last digit from the provided str value. More information on the validation algorithm on [Wikipedia](https://en.wikipedia.org/wiki/ISBN#Check_digits)

### Returns

[`str`](https://docs.python.org/3/builtins/stdtypes.html#str) -- The calculated last digit of the ISBN-13 value.

### Parameters

**`isbn`** : [`str`](https://docs.python.org/3/builtins/stdtypes.html#str)

The str value representing the ISBN in 13 digits.

## Related pages

- [API Documentation](./api-documentation-index.md)
- [Concepts](./concepts-index.md)
- [Dev Tools](./dev-tools-index.md)
- [Error Messages](./error-messages-index.md)
- [Examples](./examples-index.md)
- [Integrations](./integrations-index.md)
- [Internals](./internals-index.md)
- [Production Tools](./production-tools-index.md)
- [Pydantic](./pydantic-index.md)
- [Pydantic Core](./pydantic-core-index.md)

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