Writing templates

~~~~~~~~~~~~~~~~~

A template looks like a Ledger entry with a couple of differences:

* You don't write the first payee line.

* Instead of writing specific currency amounts, you write simple expressions to calculate amounts.

Here's a simple template for Patreon patron payments::

  [DEFAULT]

  patreon income ledger entry =

    ;Tag: Value

    Income:Patreon  -{amount}

    Accrued:Accounts Receivable:Patreon  {amount}

Let's walk through this line by line.

Every setting in your configuration file has to be in a section.  ``[DEFAULT]`` is the default section, and import2ledger reads configuration settings from here if you don't specify another one.  This documentation explains how to use sections later.

``patreon income ledger entry =`` specifies which entry template this is.  Every template is found from a setting with a name in the pattern ``<SOURCE> <TYPE> ledger entry``.  The remaining lines are indented further than this name; this defines a multiline value.  Don't worry about the exact indentation of your template; import2ledger will indent its output nicely.

The first line of the template is a Ledger tag.  The program will leave all kinds of tags and Ledger comments alone, except to indent them nicely.

import2ledger uses decimal math to calculate each amount, and rounds to the number of digits appropriate for that currency.  If the amount of currency being imported doesn't split evenly, spare change will be allocated to the last split to keep the entry balanced on both sides.

Refer to the `Python documentation for INI file structure <https://docs.python.org/3/library/configparser.html#supported-ini-file-structure>`_ for full details of the syntax.  Note that import2ledger doesn't use ``;`` as a comment prefix, since that's the primary comment prefix in Ledger.

Template variables

~~~~~~~~~~~~~~~~~~

import2ledger templates have access to a few variables for each transaction that can be included anywhere in the entry, not just amount expressions.  In other parts of the entry, they're treated as strings, and you can control their formatting using `Python's format string syntax <https://docs.python.org/3/library/string.html#formatstrings>`_.  For example, this template customizes the payee line and sets different payees for each side of the transaction::

  patreon income ledger entry =

    {date}  Patreon payment from {payee}

    Income:Patreon  -{amount}

    ;Payee: {payee}

    Accrued:Accounts Receivable:Patreon  {amount}

    ;Payee: Patreon

Templates automatically detect whether or not you have a custom payee line by checking if the first line begins with a date variable.  If it does, it's assumed to be your payee line.  Otherwise, the template uses a default payee line of ``{date} {payee}``.

Every template can use the following variables:

================== ==========================================================

Name               Contents

================== ==========================================================

    def __iter__(self):

        for ttype, tvalue, _, _, _ in self.in_tokens:

            try:

                transformer = getattr(self, 'transform_' + tokenize.tok_name[ttype])

            except AttributeError:

                raise ValueError("{} token {!r} not supported".format(ttype, tvalue))

            yield from transformer(ttype, tvalue)

    def _noop_transformer(self, ttype, tvalue):

        yield (ttype, tvalue)

    transform_ENDMARKER = _noop_transformer

    def transform_ENCODING(self, ttype, tvalue):

        self.in_encoding = tvalue

        return self._noop_transformer(ttype, tvalue)

    def transform(self):

        out_bytes = tokenize.untokenize(self)

        return out_bytes.decode(self.in_encoding)

class AmountTokenTransformer(TokenTransformer):

    def __iter__(self):

        tokens = super().__iter__()

        for token in tokens:

            yield token

            if token[0] == tokenize.NAME:

                break

        else:

            raise ValueError("no amount in expression")

        yield from tokens

    def transform_NUMBER(self, ttype, tvalue):

        yield (tokenize.NAME, 'Decimal')

        yield (tokenize.OP, '(')

        yield (tokenize.STRING, repr(tvalue))

        yield (tokenize.OP, ')')

    def transform_OP(self, ttype, tvalue):

        if tvalue == '{':

            try:

                name_type, name_value, _, _, _ = next(self.in_tokens)

                close_type, close_value, _, _, _ = next(self.in_tokens)

                if (name_type != tokenize.NAME

                    or name_value != name_value.lower()

                    or close_type != tokenize.OP

                    or close_value != '}'):

                    raise ValueError()

            except (StopIteration, ValueError):

                raise ValueError("opening { does not name variable")

            yield (tokenize.NAME, name_value)

        elif tvalue in self.SUPPORTED_OPS:

            yield from self._noop_transformer(ttype, tvalue)

        else:

            raise ValueError("unsupported operator {!r}".format(tvalue))

 Income:Donations:General     -.045  * {amount}

 ;Entity: {entity}

[Multivalue]

template =

 Expenses:Taxes  {tax}

 ;TaxAuthority: IRS

 Accrued:Accounts Receivable  {amount} - {tax}

 Income:RBI         -.1*{amount}

 Income:Donations   -.9*{amount}

[Custom Payee]

template =  {custom_date}  {payee} - Custom

 Accrued:Accounts Receivable  {amount}

 Income:Donations  -{amount}

[Multisplit]

template =

 Assets:Cash  {amount}

 Income:Sales  -{amount} + {item_sales}

 ; :NonItem:

 Income:Sales  -{item_sales}

 ; :Item:

[Empty]

template =

[Nonexistent]

def test_custom_payee_line():

    render_vars = template_vars('ZZ', '10.00', other_vars={

        'custom_date': datetime.date(2014, 2, 13),

    })

    lines = render_lines(render_vars, 'Custom Payee')

    assert lines == [

        "",

        "2014/02/13  ZZ - Custom",

        "  Accrued:Accounts Receivable  10.00 USD",

        "  Income:Donations  -10.00 USD",

    ]

def test_line1_not_custom_payee():

    render_vars = template_vars('VV', '15.00', other_vars={

        'custom_date': datetime.date(2014, 2, 12),

    })

    lines = render_lines(render_vars, 'Simplest')

    assert lines == [

        "",

        "2015/03/14 VV",

        "  Accrued:Accounts Receivable  15.00 USD",

        "  Income:Donations  -15.00 USD",

    ]

@pytest.mark.parametrize('amount_expr', [

    '',

    'name',

    '-',

    '()',

    '+()',

    '{}',

    '{{}}',

    '{()}',

    '{name',

    'name}',

    '{42}',

    '(5).real',

    '{amount.real}',

    '{amount.is_nan()}',

    '{Decimal}',

    '{FOO}',

])

def test_bad_amount_expression(amount_expr):

    with pytest.raises(errors.UserInputError):

        ledger_entry.Template(" Income  " + amount_expr)

class Config:

    def __init__(self, use_section):