### Navigation

- index
- modules |
- next |
- previous |
- IPython v0.10.1 documentation »
- The IPython API »

# external.validate

## Module: `external.validate`

Inheritance diagram for `IPython.external.validate`:

The Validator object is used to check that supplied values conform to a specification.

The value can be supplied as a string - e.g. from a config file. In this case the check will also convert the value to the required type. This allows you to add validation as a transparent layer to access data stored as strings. The validation checks that the data is correct and converts it to the expected type.

Some standard checks are provided for basic data types. Additional checks are easy to write. They can be provided when the `Validator` is instantiated or added afterwards.

The standard functions work with the following basic data types :

- integers
- floats
- booleans
- strings
- ip_addr

plus lists of these datatypes

Adding additional checks is done through coding simple functions.

The full set of standard checks are :

- ‘integer’: matches integer values (including negative)

    Takes optional ‘min’ and ‘max’ arguments :

        integer()
        integer(3, 9)  # any value from 3 to 9
        integer(min=0) # any positive value
        integer(max=9)

- ‘float’: matches float values

    Has the same parameters as the integer check.

- ‘boolean’: matches boolean values - `True` or `False`
    Acceptable string values for True are :

      true, on, yes, 1

    Acceptable string values for False are :

      false, off, no, 0

    Any other value raises an error.

- ‘ip_addr’: matches an Internet Protocol address, v.4, represented

    by a dotted-quad string, i.e. ‘1.2.3.4’.

- ‘string’: matches any string.

    Takes optional keyword args ‘min’ and ‘max’ to specify min and max lengths of the string.

- ‘list’: matches any list.

    Takes optional keyword args ‘min’, and ‘max’ to specify min and max sizes of the list. (Always returns a list.)

- ‘tuple’: matches any tuple.

    Takes optional keyword args ‘min’, and ‘max’ to specify min and max sizes of the tuple. (Always returns a tuple.)

- ‘int_list’: Matches a list of integers.

    Takes the same arguments as list.

- ‘float_list’: Matches a list of floats.

    Takes the same arguments as list.

- ‘bool_list’: Matches a list of boolean values.

    Takes the same arguments as list.

- ‘ip_addr_list’: Matches a list of IP addresses.

    Takes the same arguments as list.

- ‘string_list’: Matches a list of strings.

    Takes the same arguments as list.

- ‘mixed_list’: Matches a list with different types in

    specific positions. List size must match the number of arguments.

    Each position can be one of : ‘integer’, ‘float’, ‘ip_addr’, ‘string’, ‘boolean’

    So to specify a list with two strings followed by two integers, you write the check as :

        mixed_list('string', 'string', 'integer', 'integer')

- ‘pass’: This check matches everything ! It never fails

    and the value is unchanged.

    It is also the default if no check is specified.

- ‘option’: This check matches any from a list of options.

    You specify this check with :

        option('option 1', 'option 2', 'option 3')

You can supply a default value (returned if no value is supplied) using the default keyword argument.

You specify a list argument for default using a list constructor syntax in the check :

    checkname(arg1, arg2, default=list('val 1', 'val 2', 'val 3'))

A badly formatted set of arguments will raise a `VdtParamError`.

## Classes

### `ValidateError`

class `IPython.external.validate.``ValidateError`

  Bases: `exceptions.Exception`

  This error indicates that the check failed. It can be the base class for more specific errors.

  Any check function that fails ought to raise this error. (or a subclass)

      >>> raise ValidateError
      Traceback (most recent call last):
      ValidateError

  `__init__`()

    x.__init__(...) initializes x; see x.__class__.__doc__ for signature

### `Validator`

class `IPython.external.validate.``Validator`(functions=None)

  Bases: `object`

  Validator is an object that allows you to register a set of ‘checks’. These checks take input and test that it conforms to the check.

  This can also involve converting the value from a string into the correct datatype.

  The `check` method takes an input string which configures which check is to be used and applies that check to a supplied value.

  An example input string would be: ‘int_range(param1, param2)’

  You would then provide something like:

      >>> def int_range_check(value, min, max):
      ...     # turn min and max from strings to integers
      ...     min = int(min)
      ...     max = int(max)
      ...     # check that value is of the correct type.
      ...     # possible valid inputs are integers or strings
      ...     # that represent integers
      ...     if not isinstance(value, (int, long, StringTypes)):
      ...         raise VdtTypeError(value)
      ...     elif isinstance(value, StringTypes):
      ...         # if we are given a string
      ...         # attempt to convert to an integer
      ...         try:
      ...             value = int(value)
      ...         except ValueError:
      ...             raise VdtValueError(value)
      ...     # check the value is between our constraints
      ...     if not min <= value:
      ...          raise VdtValueTooSmallError(value)
      ...     if not value <= max:
      ...          raise VdtValueTooBigError(value)
      ...     return value

      >>> fdict = {'int_range': int_range_check}
      >>> vtr1 = Validator(fdict)
      >>> vtr1.check('int_range(20, 40)', '30')
      30
      >>> vtr1.check('int_range(20, 40)', '60')
      Traceback (most recent call last):
      VdtValueTooBigError: the value "60" is too big.

  New functions can be added with :

      >>> vtr2 = Validator()
      >>> vtr2.functions['int_range'] = int_range_check

  Or by passing in a dictionary of functions when Validator is instantiated.

  Your functions can use keyword arguments, but the first argument should always be ‘value’.

  If the function doesn’t take additional arguments, the parentheses are optional in the check. It can be written with either of :

      keyword = function_name
      keyword = function_name()

  The first program to utilise Validator() was Michael Foord’s ConfigObj, an alternative to ConfigParser which supports lists and can validate a config file using a config schema. For more details on using Validator with ConfigObj see: http://www.voidspace.org.uk/python/configobj.html

  `__init__`()

        >>> vtri = Validator()

  `check`()

    Usage: check(check, value)

    Arguments:
      check: string representing check to apply (including arguments) value: object to be checked

    Returns value, converted to correct type if necessary

    If the check fails, raises a `ValidateError` subclass.

        >>> vtor.check('yoda', '')
        Traceback (most recent call last):
        VdtUnknownCheckError: the check "yoda" is unknown.
        >>> vtor.check('yoda()', '')
        Traceback (most recent call last):
        VdtUnknownCheckError: the check "yoda" is unknown.

        >>> vtor.check('string(default="")', '', missing=True)
        ''

  `get_default_value`()

    Given a check, return the default value for the check (converted to the right type).

    If the check doesn’t specify a default value then a `KeyError` will be raised.

### `VdtMissingValue`

class `IPython.external.validate.``VdtMissingValue`

  Bases: `IPython.external.validate.ValidateError`

  No value was supplied to a check that needed one.

  `__init__`()

    x.__init__(...) initializes x; see x.__class__.__doc__ for signature

### `VdtParamError`

class `IPython.external.validate.``VdtParamError`(name, value)

  Bases: `exceptions.SyntaxError`

  An incorrect parameter was passed

  `__init__`()

        >>> raise VdtParamError('yoda', 'jedi')
        Traceback (most recent call last):
        VdtParamError: passed an incorrect value "jedi" for parameter "yoda".

### `VdtTypeError`

class `IPython.external.validate.``VdtTypeError`(value)

  Bases: `IPython.external.validate.ValidateError`

  The value supplied was of the wrong type

  `__init__`()

        >>> raise VdtTypeError('jedi')
        Traceback (most recent call last):
        VdtTypeError: the value "jedi" is of the wrong type.

### `VdtUnknownCheckError`

class `IPython.external.validate.``VdtUnknownCheckError`(value)

  Bases: `IPython.external.validate.ValidateError`

  An unknown check function was requested

  `__init__`()

        >>> raise VdtUnknownCheckError('yoda')
        Traceback (most recent call last):
        VdtUnknownCheckError: the check "yoda" is unknown.

### `VdtValueError`

class `IPython.external.validate.``VdtValueError`(value)

  Bases: `IPython.external.validate.ValidateError`

  The value supplied was of the correct type, but was not an allowed value.

  `__init__`()

        >>> raise VdtValueError('jedi')
        Traceback (most recent call last):
        VdtValueError: the value "jedi" is unacceptable.

### `VdtValueTooBigError`

class `IPython.external.validate.``VdtValueTooBigError`(value)

  Bases: `IPython.external.validate.VdtValueError`

  The value supplied was of the correct type, but was too big.

  `__init__`()

        >>> raise VdtValueTooBigError('1')
        Traceback (most recent call last):
        VdtValueTooBigError: the value "1" is too big.

### `VdtValueTooLongError`

class `IPython.external.validate.``VdtValueTooLongError`(value)

  Bases: `IPython.external.validate.VdtValueError`

  The value supplied was of the correct type, but was too long.

  `__init__`()

        >>> raise VdtValueTooLongError('jedie')
        Traceback (most recent call last):
        VdtValueTooLongError: the value "jedie" is too long.

### `VdtValueTooShortError`

class `IPython.external.validate.``VdtValueTooShortError`(value)

  Bases: `IPython.external.validate.VdtValueError`

  The value supplied was of the correct type, but was too short.

  `__init__`()

        >>> raise VdtValueTooShortError('jed')
        Traceback (most recent call last):
        VdtValueTooShortError: the value "jed" is too short.

### `VdtValueTooSmallError`

class `IPython.external.validate.``VdtValueTooSmallError`(value)

  Bases: `IPython.external.validate.VdtValueError`

  The value supplied was of the correct type, but was too small.

  `__init__`()

        >>> raise VdtValueTooSmallError('0')
        Traceback (most recent call last):
        VdtValueTooSmallError: the value "0" is too small.

## Functions

`IPython.external.validate.``dottedQuadToNum`()

  Convert decimal dotted quad string to long integer

      >>> dottedQuadToNum('1 ')
      1L
      >>> dottedQuadToNum(' 1.2')
      16777218L
      >>> dottedQuadToNum(' 1.2.3 ')
      16908291L
      >>> dottedQuadToNum('1.2.3.4')
      16909060L
      >>> dottedQuadToNum('1.2.3. 4')
      Traceback (most recent call last):
      ValueError: Not a good dotted-quad IP: 1.2.3. 4
      >>> dottedQuadToNum('255.255.255.255')
      4294967295L
      >>> dottedQuadToNum('255.255.255.256')
      Traceback (most recent call last):
      ValueError: Not a good dotted-quad IP: 255.255.255.256

`IPython.external.validate.``is_bool_list`()

  Check that the value is a list of booleans.

  You can optionally specify the minimum and maximum number of members.

  Each list member is checked that it is a boolean.

      >>> vtor.check('bool_list', ())
      []
      >>> vtor.check('bool_list', [])
      []
      >>> check_res = vtor.check('bool_list', (True, False))
      >>> check_res == [True, False]
      1
      >>> check_res = vtor.check('bool_list', [True, False])
      >>> check_res == [True, False]
      1
      >>> vtor.check('bool_list', [True, 'a'])
      Traceback (most recent call last):
      VdtTypeError: the value "a" is of the wrong type.

`IPython.external.validate.``is_boolean`()

  Check if the value represents a boolean.

      >>> vtor.check('boolean', 0)
      0
      >>> vtor.check('boolean', False)
      0
      >>> vtor.check('boolean', '0')
      0
      >>> vtor.check('boolean', 'off')
      0
      >>> vtor.check('boolean', 'false')
      0
      >>> vtor.check('boolean', 'no')
      0
      >>> vtor.check('boolean', 'nO')
      0
      >>> vtor.check('boolean', 'NO')
      0
      >>> vtor.check('boolean', 1)
      1
      >>> vtor.check('boolean', True)
      1
      >>> vtor.check('boolean', '1')
      1
      >>> vtor.check('boolean', 'on')
      1
      >>> vtor.check('boolean', 'true')
      1
      >>> vtor.check('boolean', 'yes')
      1
      >>> vtor.check('boolean', 'Yes')
      1
      >>> vtor.check('boolean', 'YES')
      1
      >>> vtor.check('boolean', '')
      Traceback (most recent call last):
      VdtTypeError: the value "" is of the wrong type.
      >>> vtor.check('boolean', 'up')
      Traceback (most recent call last):
      VdtTypeError: the value "up" is of the wrong type.

`IPython.external.validate.``is_float`()

  A check that tests that a given value is a float (an integer will be accepted), and optionally - that it is between bounds.

  If the value is a string, then the conversion is done - if possible. Otherwise a VdtError is raised.

  This can accept negative values.

      >>> vtor.check('float', '2')
      2.0

  From now on we multiply the value to avoid comparing decimals

      >>> vtor.check('float', '-6.8') * 10
      -68.0
      >>> vtor.check('float', '12.2') * 10
      122.0
      >>> vtor.check('float', 8.4) * 10
      84.0
      >>> vtor.check('float', 'a')
      Traceback (most recent call last):
      VdtTypeError: the value "a" is of the wrong type.
      >>> vtor.check('float(10.1)', '10.2') * 10
      102.0
      >>> vtor.check('float(max=20.2)', '15.1') * 10
      151.0
      >>> vtor.check('float(10.0)', '9.0')
      Traceback (most recent call last):
      VdtValueTooSmallError: the value "9.0" is too small.
      >>> vtor.check('float(max=20.0)', '35.0')
      Traceback (most recent call last):
      VdtValueTooBigError: the value "35.0" is too big.

`IPython.external.validate.``is_float_list`()

  Check that the value is a list of floats.

  You can optionally specify the minimum and maximum number of members.

  Each list member is checked that it is a float.

      >>> vtor.check('float_list', ())
      []
      >>> vtor.check('float_list', [])
      []
      >>> vtor.check('float_list', (1, 2.0))
      [1.0, 2.0]
      >>> vtor.check('float_list', [1, 2.0])
      [1.0, 2.0]
      >>> vtor.check('float_list', [1, 'a'])
      Traceback (most recent call last):
      VdtTypeError: the value "a" is of the wrong type.

`IPython.external.validate.``is_int_list`()

  Check that the value is a list of integers.

  You can optionally specify the minimum and maximum number of members.

  Each list member is checked that it is an integer.

      >>> vtor.check('int_list', ())
      []
      >>> vtor.check('int_list', [])
      []
      >>> vtor.check('int_list', (1, 2))
      [1, 2]
      >>> vtor.check('int_list', [1, 2])
      [1, 2]
      >>> vtor.check('int_list', [1, 'a'])
      Traceback (most recent call last):
      VdtTypeError: the value "a" is of the wrong type.

`IPython.external.validate.``is_integer`()

  A check that tests that a given value is an integer (int, or long) and optionally, between bounds. A negative value is accepted, while a float will fail.

  If the value is a string, then the conversion is done - if possible. Otherwise a VdtError is raised.

      >>> vtor.check('integer', '-1')
      -1
      >>> vtor.check('integer', '0')
      0
      >>> vtor.check('integer', 9)
      9
      >>> vtor.check('integer', 'a')
      Traceback (most recent call last):
      VdtTypeError: the value "a" is of the wrong type.
      >>> vtor.check('integer', '2.2')
      Traceback (most recent call last):
      VdtTypeError: the value "2.2" is of the wrong type.
      >>> vtor.check('integer(10)', '20')
      20
      >>> vtor.check('integer(max=20)', '15')
      15
      >>> vtor.check('integer(10)', '9')
      Traceback (most recent call last):
      VdtValueTooSmallError: the value "9" is too small.
      >>> vtor.check('integer(10)', 9)
      Traceback (most recent call last):
      VdtValueTooSmallError: the value "9" is too small.
      >>> vtor.check('integer(max=20)', '35')
      Traceback (most recent call last):
      VdtValueTooBigError: the value "35" is too big.
      >>> vtor.check('integer(max=20)', 35)
      Traceback (most recent call last):
      VdtValueTooBigError: the value "35" is too big.
      >>> vtor.check('integer(0, 9)', False)
      0

`IPython.external.validate.``is_ip_addr`()

  Check that the supplied value is an Internet Protocol address, v.4, represented by a dotted-quad string, i.e. ‘1.2.3.4’.

      >>> vtor.check('ip_addr', '1 ')
      '1'
      >>> vtor.check('ip_addr', ' 1.2')
      '1.2'
      >>> vtor.check('ip_addr', ' 1.2.3 ')
      '1.2.3'
      >>> vtor.check('ip_addr', '1.2.3.4')
      '1.2.3.4'
      >>> vtor.check('ip_addr', '0.0.0.0')
      '0.0.0.0'
      >>> vtor.check('ip_addr', '255.255.255.255')
      '255.255.255.255'
      >>> vtor.check('ip_addr', '255.255.255.256')
      Traceback (most recent call last):
      VdtValueError: the value "255.255.255.256" is unacceptable.
      >>> vtor.check('ip_addr', '1.2.3.4.5')
      Traceback (most recent call last):
      VdtValueError: the value "1.2.3.4.5" is unacceptable.
      >>> vtor.check('ip_addr', '1.2.3. 4')
      Traceback (most recent call last):
      VdtValueError: the value "1.2.3. 4" is unacceptable.
      >>> vtor.check('ip_addr', 0)
      Traceback (most recent call last):
      VdtTypeError: the value "0" is of the wrong type.

`IPython.external.validate.``is_ip_addr_list`()

  Check that the value is a list of IP addresses.

  You can optionally specify the minimum and maximum number of members.

  Each list member is checked that it is an IP address.

      >>> vtor.check('ip_addr_list', ())
      []
      >>> vtor.check('ip_addr_list', [])
      []
      >>> vtor.check('ip_addr_list', ('1.2.3.4', '5.6.7.8'))
      ['1.2.3.4', '5.6.7.8']
      >>> vtor.check('ip_addr_list', ['a'])
      Traceback (most recent call last):
      VdtValueError: the value "a" is unacceptable.

`IPython.external.validate.``is_list`()

  Check that the value is a list of values.

  You can optionally specify the minimum and maximum number of members.

  It does no check on list members.

      >>> vtor.check('list', ())
      []
      >>> vtor.check('list', [])
      []
      >>> vtor.check('list', (1, 2))
      [1, 2]
      >>> vtor.check('list', [1, 2])
      [1, 2]
      >>> vtor.check('list(3)', (1, 2))
      Traceback (most recent call last):
      VdtValueTooShortError: the value "(1, 2)" is too short.
      >>> vtor.check('list(max=5)', (1, 2, 3, 4, 5, 6))
      Traceback (most recent call last):
      VdtValueTooLongError: the value "(1, 2, 3, 4, 5, 6)" is too long.
      >>> vtor.check('list(min=3, max=5)', (1, 2, 3, 4))
      [1, 2, 3, 4]
      >>> vtor.check('list', 0)
      Traceback (most recent call last):
      VdtTypeError: the value "0" is of the wrong type.
      >>> vtor.check('list', '12')
      Traceback (most recent call last):
      VdtTypeError: the value "12" is of the wrong type.

`IPython.external.validate.``is_mixed_list`()

  Check that the value is a list. Allow specifying the type of each member. Work on lists of specific lengths.

  You specify each member as a positional argument specifying type

  Each type should be one of the following strings :
    ‘integer’, ‘float’, ‘ip_addr’, ‘string’, ‘boolean’

  So you can specify a list of two strings, followed by two integers as :

  > mixed_list(‘string’, ‘string’, ‘integer’, ‘integer’)

  The length of the list must match the number of positional arguments you supply.

      >>> mix_str = "mixed_list('integer', 'float', 'ip_addr', 'string', 'boolean')"
      >>> check_res = vtor.check(mix_str, (1, 2.0, '1.2.3.4', 'a', True))
      >>> check_res == [1, 2.0, '1.2.3.4', 'a', True]
      1
      >>> check_res = vtor.check(mix_str, ('1', '2.0', '1.2.3.4', 'a', 'True'))
      >>> check_res == [1, 2.0, '1.2.3.4', 'a', True]
      1
      >>> vtor.check(mix_str, ('b', 2.0, '1.2.3.4', 'a', True))
      Traceback (most recent call last):
      VdtTypeError: the value "b" is of the wrong type.
      >>> vtor.check(mix_str, (1, 2.0, '1.2.3.4', 'a'))
      Traceback (most recent call last):
      VdtValueTooShortError: the value "(1, 2.0, '1.2.3.4', 'a')" is too short.
      >>> vtor.check(mix_str, (1, 2.0, '1.2.3.4', 'a', 1, 'b'))
      Traceback (most recent call last):
      VdtValueTooLongError: the value "(1, 2.0, '1.2.3.4', 'a', 1, 'b')" is too long.
      >>> vtor.check(mix_str, 0)
      Traceback (most recent call last):
      VdtTypeError: the value "0" is of the wrong type.

  This test requires an elaborate setup, because of a change in error string output from the interpreter between Python 2.2 and 2.3 .

      >>> res_seq = (
      ...     'passed an incorrect value "',
      ...     'yoda',
      ...     '" for parameter "mixed_list".',
      ... )
      >>> if INTP_VER == (2, 2):
      ...     res_str = "".join(res_seq)
      ... else:
      ...     res_str = "'".join(res_seq)
      >>> try:
      ...     vtor.check('mixed_list("yoda")', ('a'))
      ... except VdtParamError, err:
      ...     str(err) == res_str
      1

`IPython.external.validate.``is_option`()

  This check matches the value to any of a set of options.

      >>> vtor.check('option("yoda", "jedi")', 'yoda')
      'yoda'
      >>> vtor.check('option("yoda", "jedi")', 'jed')
      Traceback (most recent call last):
      VdtValueError: the value "jed" is unacceptable.
      >>> vtor.check('option("yoda", "jedi")', 0)
      Traceback (most recent call last):
      VdtTypeError: the value "0" is of the wrong type.

`IPython.external.validate.``is_string`()

  Check that the supplied value is a string.

  You can optionally specify the minimum and maximum number of members.

      >>> vtor.check('string', '0')
      '0'
      >>> vtor.check('string', 0)
      Traceback (most recent call last):
      VdtTypeError: the value "0" is of the wrong type.
      >>> vtor.check('string(2)', '12')
      '12'
      >>> vtor.check('string(2)', '1')
      Traceback (most recent call last):
      VdtValueTooShortError: the value "1" is too short.
      >>> vtor.check('string(min=2, max=3)', '123')
      '123'
      >>> vtor.check('string(min=2, max=3)', '1234')
      Traceback (most recent call last):
      VdtValueTooLongError: the value "1234" is too long.

`IPython.external.validate.``is_string_list`()

  Check that the value is a list of strings.

  You can optionally specify the minimum and maximum number of members.

  Each list member is checked that it is a string.

      >>> vtor.check('string_list', ())
      []
      >>> vtor.check('string_list', [])
      []
      >>> vtor.check('string_list', ('a', 'b'))
      ['a', 'b']
      >>> vtor.check('string_list', ['a', 1])
      Traceback (most recent call last):
      VdtTypeError: the value "1" is of the wrong type.
      >>> vtor.check('string_list', 'hello')
      Traceback (most recent call last):
      VdtTypeError: the value "hello" is of the wrong type.

`IPython.external.validate.``is_tuple`()

  Check that the value is a tuple of values.

  You can optionally specify the minimum and maximum number of members.

  It does no check on members.

      >>> vtor.check('tuple', ())
      ()
      >>> vtor.check('tuple', [])
      ()
      >>> vtor.check('tuple', (1, 2))
      (1, 2)
      >>> vtor.check('tuple', [1, 2])
      (1, 2)
      >>> vtor.check('tuple(3)', (1, 2))
      Traceback (most recent call last):
      VdtValueTooShortError: the value "(1, 2)" is too short.
      >>> vtor.check('tuple(max=5)', (1, 2, 3, 4, 5, 6))
      Traceback (most recent call last):
      VdtValueTooLongError: the value "(1, 2, 3, 4, 5, 6)" is too long.
      >>> vtor.check('tuple(min=3, max=5)', (1, 2, 3, 4))
      (1, 2, 3, 4)
      >>> vtor.check('tuple', 0)
      Traceback (most recent call last):
      VdtTypeError: the value "0" is of the wrong type.
      >>> vtor.check('tuple', '12')
      Traceback (most recent call last):
      VdtTypeError: the value "12" is of the wrong type.

`IPython.external.validate.``numToDottedQuad`()

  Convert long int to dotted quad string

      >>> numToDottedQuad(-1L)
      Traceback (most recent call last):
      ValueError: Not a good numeric IP: -1
      >>> numToDottedQuad(1L)
      '0.0.0.1'
      >>> numToDottedQuad(16777218L)
      '1.0.0.2'
      >>> numToDottedQuad(16908291L)
      '1.2.0.3'
      >>> numToDottedQuad(16909060L)
      '1.2.3.4'
      >>> numToDottedQuad(4294967295L)
      '255.255.255.255'
      >>> numToDottedQuad(4294967296L)
      Traceback (most recent call last):
      ValueError: Not a good numeric IP: 4294967296

### Navigation

- index
- modules |
- next |
- previous |
- IPython v0.10.1 documentation »
- The IPython API »