data: Add Posting.from_entries() method.

conservancy_beancount/data.py

@@ -40,6 +40,7 @@ from typing import (
 )
 
 from .beancount_types import (
+    Directive,
     MetaKey,
     MetaValue,
     Posting as BasePosting,
@@ -294,6 +295,19 @@ class Posting(BasePosting):
         for index, post in enumerate(txn.postings):
             yield cls.from_beancount(txn, index, post)
 
+    @classmethod
+    def from_entries(cls, entries: Iterable[Directive]) -> Iterable['Posting']:
+        """Yield an enhanced Posting object for every posting in these entries"""
+        for entry in entries:
+            # Because Beancount's own Transaction class isn't type-checkable,
+            # we can't statically check this. Might as well rely on duck
+            # typing while we're at it: just try to yield postings from
+            # everything, and ignore entries that lack a postings attribute.
+            try:
+                yield from cls.from_txn(entry)  # type:ignore[arg-type]
+            except AttributeError:
+                pass
+
 
 def balance_of(txn: Transaction,
                *preds: Callable[[Account], Optional[bool]],

tests/test_data_posting.py

@@ -18,6 +18,8 @@ import pytest
 
 from . import testutil
 
+from beancount.core import data as bc_data
+
 from conservancy_beancount import data
 
 @pytest.fixture
@@ -57,3 +59,26 @@ def test_from_txn(simple_txn):
         assert all(source[x] == post[x] for x in range(len(source) - 1))
         assert isinstance(post.account, data.Account)
         assert post.meta['note']  # Only works with PostingMeta
+
+def test_from_entries_two_txns(simple_txn):
+    entries = [simple_txn, simple_txn]
+    sources = [post for txn in entries for post in txn.postings]
+    for source, post in zip(sources, data.Posting.from_entries(entries)):
+        assert all(source[x] == post[x] for x in range(len(source) - 1))
+        assert isinstance(post.account, data.Account)
+        assert post.meta['note']  # Only works with PostingMeta
+
+def test_from_entries_mix_txns_and_other_directives(simple_txn):
+    meta = {
+        'filename': __file__,
+        'lineno': 75,
+    }
+    entries = [
+        bc_data.Commodity(meta, testutil.FY_START_DATE, 'EUR'),
+        bc_data.Commodity(meta, testutil.FY_START_DATE, 'USD'),
+        simple_txn,
+    ]
+    for source, post in zip(simple_txn.postings, data.Posting.from_entries(entries)):
+        assert all(source[x] == post[x] for x in range(len(source) - 1))
+        assert isinstance(post.account, data.Account)
+        assert post.meta['note']  # Only works with PostingMeta