GnuCash SQL output.

src/pricehist/outputs/__init__.py

@@ -1,5 +1,6 @@
 from .beancount import Beancount
 from .csv import CSV
+from .gnucashsql import GnuCashSQL
 from .ledger import Ledger
 
 default = 'ledger'
@@ -7,5 +8,6 @@ default = 'ledger'
 by_type = {
     'beancount': Beancount,
     'csv': CSV,
+    'gnucash-sql': GnuCashSQL,
     'ledger': Ledger
 }

src/pricehist/outputs/gnucashsql.py

@@ -0,0 +1,71 @@
+from datetime import datetime
+import hashlib
+
+from pricehist import __version__
+
+class GnuCashSQL():
+
+    def format(self, prices):
+        source = 'pricehist'
+        typ = 'unknown'
+
+        values = []
+        for price in prices:
+            date = f'{price.date} 00:00:00'
+            m = hashlib.sha256()
+            m.update("".join([date, price.base, price.quote, source, typ, str(price.amount)]).encode('utf-8'))
+            guid = m.hexdigest()[0:32]
+            value_num = str(price.amount).replace('.', '')
+            value_denom = 10 ** len(f'{price.amount}.'.split('.')[1])
+            v = f"('{guid}', '{date}', '{price.base}', '{price.quote}', '{source}', '{typ}', {value_num}, {value_denom})"
+            values.append(v)
+
+        comma_newline = ",\n"
+        sql = f'''\
+-- Created by pricehist v{__version__} at {datetime.utcnow().isoformat()}Z
+
+BEGIN;
+
+-- The GnuCash database must already have entries for the relevant commodities.
+-- These statements fail and later changes are skipped if that isn't the case.
+CREATE TEMPORARY TABLE guids (mnemonic TEXT NOT NULL, guid TEXT NOT NULL);
+INSERT INTO guids VALUES ('{price.base}', (SELECT guid FROM commodities WHERE mnemonic = '{price.base}' LIMIT 1));
+INSERT INTO guids VALUES ('{price.quote}', (SELECT guid FROM commodities WHERE mnemonic = '{price.quote}' LIMIT 1));
+
+-- Create a staging table for the new price data.
+-- Doing this via a SELECT ensures the correct date type across databases.
+CREATE TEMPORARY TABLE new_prices AS
+SELECT p.guid, p.date, c.mnemonic AS base, c.mnemonic AS quote, p.source, p.type, p.value_num, p.value_denom
+FROM prices p, commodities c
+WHERE FALSE;
+
+-- Populate the staging table.
+INSERT INTO new_prices (guid, date, base, quote, source, type, value_num, value_denom) VALUES
+{comma_newline.join(values)}
+;
+
+-- Get some numbers for the summary.
+CREATE TEMPORARY TABLE summary (description TEXT, num INT);
+INSERT INTO summary VALUES ('staged rows', (SELECT COUNT(*) FROM new_prices));
+INSERT INTO summary VALUES ('existing rows', (SELECT COUNT(*) FROM new_prices tp, prices p where p.guid = tp.guid));
+INSERT INTO summary VALUES ('additional rows', (SELECT COUNT(*) FROM new_prices WHERE guid NOT IN (SELECT guid FROM prices)));
+
+-- Insert the new prices into the prices table, unless they're already there.
+INSERT INTO prices (guid, commodity_guid, currency_guid, date, source, type, value_num, value_denom)
+SELECT tp.guid, g1.guid, g2.guid, tp.date, tp.source, tp.type, tp.value_num, tp.value_denom
+FROM new_prices tp, guids g1, guids g2
+WHERE tp.base = g1.mnemonic
+  AND tp.quote = g2.mnemonic
+  AND tp.guid NOT IN (SELECT guid FROM prices)
+;
+
+-- Show the summary.
+SELECT * FROM summary;
+
+-- Show the final relevant rows of the main prices table
+SELECT 'final' AS status, p.* FROM prices p WHERE p.guid IN (SELECT guid FROM new_prices) ORDER BY p.date;
+
+COMMIT;
+'''
+
+        return sql