AnswerDotAI · ozpau · Mar 9, 2025
diff --git a/README.md b/README.md
@@ -242,3 +242,75 @@ except: print("Delete succeeded!")
 | sqlite3.dbapi2.OperationalError | apsw.Error | General error, OperationalError is now proxied to apsw.Error |
 | sqlite3.dbapi2.OperationalError | apsw.SQLError | When an error is due to flawed SQL statements |
 | sqlite3.ProgrammingError | apsw.ConnectionClosedError | Caused by an improperly closed database file |
+
+## Handling of default values
+
+Default values are handled as expected, including expression-based
+default values:
+
+``` python
+db.execute("""
+DROP TABLE IF EXISTS migrations;
+CREATE TABLE IF NOT EXISTS migrations (
+    id INTEGER PRIMARY KEY,
+    name TEXT DEFAULT 'foo',
+    cexpr TEXT DEFAULT ('abra' || 'cadabra'),
+    rand INTEGER DEFAULT (random()),
+    unix_epoch FLOAT DEFAULT (unixepoch('subsec')),
+    json_array JSON DEFAULT (json_array(1,2,3,4)),
+    inserted_at DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL
+);
+""")
+```
+
+    <apsw.Cursor>
+
+``` python
+migrations = Table(db, 'migrations')
+migrations.default_values
+```
+
+    {'name': 'foo',
+     'cexpr': SQLExpr: 'abra' || 'cadabra',
+     'rand': SQLExpr: random(),
+     'unix_epoch': SQLExpr: unixepoch('subsec'),
+     'json_array': SQLExpr: json_array(1,2,3,4),
+     'inserted_at': SQLExpr: CURRENT_TIMESTAMP}
+
+``` python
+assert all([type(x) is SQLExpr for x in list(migrations.default_values.values())[1:]])
+```
+
+``` python
+migrations.insert(dict(id=0))
+migrations.insert(dict(id=1))
+```
+
+    <Table migrations (id, name, cexpr, rand, unix_epoch, json_array, inserted_at)>
+
+Default expressions are executed independently for each row on row
+insertion:
+
+``` python
+rows = list(migrations.rows)
+rows
+```
+
+    [{'id': 0,
+      'name': 'foo',
+      'cexpr': 'abracadabra',
+      'rand': 8201569685582150332,
+      'unix_epoch': 1741481111.188,
+      'json_array': '[1,2,3,4]',
+      'inserted_at': '2025-03-09 00:45:11'},
+     {'id': 1,
+      'name': 'foo',
+      'cexpr': 'abracadabra',
+      'rand': 1625289491289542947,
+      'unix_epoch': 1741481111.19,
+      'json_array': '[1,2,3,4]',
+      'inserted_at': '2025-03-09 00:45:11'}]
+
+``` python
+assert rows[0]['rand'] != rows[1]['rand']
+```
diff --git a/apswutils/db.py b/apswutils/db.py
@@ -1,5 +1,5 @@
 # This file is from sqlite-utils and copyright and license is the same as that project
-__all__ = ['Database', 'Queryable', 'Table', 'View']
+__all__ = ['Database', 'Queryable', 'Table', 'View', 'SQLExpr']
 
 from .utils import chunks, hash_record, suggest_column_types, types_for_column_types, column_affinity, find_spatialite, cursor_row2dict
 from collections import namedtuple
@@ -8,6 +8,7 @@
 from functools import cache
 import contextlib, datetime, decimal, inspect, itertools, json, os, pathlib, re, secrets, textwrap, binascii, uuid, logging
 import apsw, apsw.ext, apsw.bestpractice
+from fastcore.all import asdict
 
 logger = logging.getLogger('apsw')
 logger.setLevel(logging.ERROR)
@@ -3121,6 +3122,7 @@ def insert_all(
         num_records_processed = 0
         # Fix up any records with square braces in the column names
         records = fix_square_braces(records)
+        records = remove_default_sql_exprs(records)
         # We can only handle a max of 999 variables in a SQL insert, so
         # we need to adjust the batch_size down if we have too many cols
         records = iter(records)
@@ -3715,9 +3717,20 @@ def fix_square_braces(records: Iterable[Dict[str, Any]]):
         else:
             yield record
 
+def remove_default_sql_exprs(records: Iterable[Dict[str, Any]]):
+    for record in records:
+        yield {k: v for k, v in asdict(record).items() if type(v) is not SQLExpr or not v.default}
+
+class SQLExpr():
+    def __init__(self, expr, default=False): self.expr, self.default = expr, default
+    def __str__(self): return f'SQLExpr: {self.expr}'
+    __repr__ = __str__
 
+# Match anything that is not a single quote, then match anything that is an escaped single quote
+# (any number of times), then repeat the whole process
+_sql_string_datatype_matcher = re.compile(r"^'([^']*(\\')*)*'$")
 def _decode_default_value(value):
-    if value.startswith("'") and value.endswith("'"):
+    if _sql_string_datatype_matcher.match(value):
         # It's a string
         return value[1:-1]
     if value.isdigit():
@@ -3732,4 +3745,4 @@ def _decode_default_value(value):
         return float(value)
     except ValueError:
         pass
-    return value
+    return SQLExpr(value, True)
diff --git a/nbs/index.ipynb b/nbs/index.ipynb
@@ -577,6 +577,157 @@
     "|sqlite3.dbapi2.OperationalError|apsw.SQLError|When an error is due to flawed SQL statements|\n",
     "|sqlite3.ProgrammingError|apsw.ConnectionClosedError|Caused by an improperly closed database file|\n"
    ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "## Handling of default values"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Default values are handled as expected, including expression-based default values:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "<apsw.Cursor>"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "db.execute(\"\"\"\n",
+    "DROP TABLE IF EXISTS migrations;\n",
+    "CREATE TABLE IF NOT EXISTS migrations (\n",
+    "    id INTEGER PRIMARY KEY,\n",
+    "    name TEXT DEFAULT 'foo',\n",
+    "    cexpr TEXT DEFAULT ('abra' || 'cadabra'),\n",
+    "    rand INTEGER DEFAULT (random()),\n",
+    "    unix_epoch FLOAT DEFAULT (unixepoch('subsec')),\n",
+    "    json_array JSON DEFAULT (json_array(1,2,3,4)),\n",
+    "    inserted_at DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL\n",
+    ");\n",
+    "\"\"\")"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "{'name': 'foo',\n",
+       " 'cexpr': SQLExpr: 'abra' || 'cadabra',\n",
+       " 'rand': SQLExpr: random(),\n",
+       " 'unix_epoch': SQLExpr: unixepoch('subsec'),\n",
+       " 'json_array': SQLExpr: json_array(1,2,3,4),\n",
+       " 'inserted_at': SQLExpr: CURRENT_TIMESTAMP}"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "migrations = Table(db, 'migrations')\n",
+    "migrations.default_values"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "assert all([type(x) is SQLExpr for x in list(migrations.default_values.values())[1:]])"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "<Table migrations (id, name, cexpr, rand, unix_epoch, json_array, inserted_at)>"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "migrations.insert(dict(id=0))\n",
+    "migrations.insert(dict(id=1))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "Default expressions are executed independently for each row on row insertion:"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "[{'id': 0,\n",
+       "  'name': 'foo',\n",
+       "  'cexpr': 'abracadabra',\n",
+       "  'rand': 8201569685582150332,\n",
+       "  'unix_epoch': 1741481111.188,\n",
+       "  'json_array': '[1,2,3,4]',\n",
+       "  'inserted_at': '2025-03-09 00:45:11'},\n",
+       " {'id': 1,\n",
+       "  'name': 'foo',\n",
+       "  'cexpr': 'abracadabra',\n",
+       "  'rand': 1625289491289542947,\n",
+       "  'unix_epoch': 1741481111.19,\n",
+       "  'json_array': '[1,2,3,4]',\n",
+       "  'inserted_at': '2025-03-09 00:45:11'}]"
+      ]
+     },
+     "execution_count": null,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "rows = list(migrations.rows)\n",
+    "rows"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "assert rows[0]['rand'] != rows[1]['rand']"
+   ]
   }
  ],
  "metadata": {
@@ -587,5 +738,5 @@
   }
  },
  "nbformat": 4,
- "nbformat_minor": 2
+ "nbformat_minor": 4
 }