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Allow using SQL functions for default values.
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‎README.md‎

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@@ -242,3 +242,75 @@ except: print("Delete succeeded!")
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| sqlite3.dbapi2.OperationalError | apsw.Error | General error, OperationalError is now proxied to apsw.Error |
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| sqlite3.dbapi2.OperationalError | apsw.SQLError | When an error is due to flawed SQL statements |
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| sqlite3.ProgrammingError | apsw.ConnectionClosedError | Caused by an improperly closed database file |
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## Handling of default values
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Default values are handled as expected, including expression-based
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default values:
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``` python
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db.execute("""
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DROP TABLE IF EXISTS migrations;
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CREATE TABLE IF NOT EXISTS migrations (
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id INTEGER PRIMARY KEY,
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name TEXT DEFAULT 'foo',
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cexpr TEXT DEFAULT ('abra' || 'cadabra'),
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rand INTEGER DEFAULT (random()),
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unix_epoch FLOAT DEFAULT (unixepoch('subsec')),
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json_array JSON DEFAULT (json_array(1,2,3,4)),
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inserted_at DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL
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);
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""")
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```
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<apsw.Cursor>
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``` python
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migrations = Table(db, 'migrations')
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migrations.default_values
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```
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{'name': 'foo',
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'cexpr': SQLExpr: 'abra' || 'cadabra',
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'rand': SQLExpr: random(),
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'unix_epoch': SQLExpr: unixepoch('subsec'),
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'json_array': SQLExpr: json_array(1,2,3,4),
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'inserted_at': SQLExpr: CURRENT_TIMESTAMP}
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``` python
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assert all([type(x) is SQLExpr for x in list(migrations.default_values.values())[1:]])
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```
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``` python
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migrations.insert(dict(id=0))
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migrations.insert(dict(id=1))
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```
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<Table migrations (id, name, cexpr, rand, unix_epoch, json_array, inserted_at)>
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Default expressions are executed independently for each row on row
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insertion:
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``` python
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rows = list(migrations.rows)
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rows
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```
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[{'id': 0,
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'name': 'foo',
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'cexpr': 'abracadabra',
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'rand': 8201569685582150332,
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'unix_epoch': 1741481111.188,
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'json_array': '[1,2,3,4]',
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'inserted_at': '2025-03-09 00:45:11'},
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{'id': 1,
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'name': 'foo',
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'cexpr': 'abracadabra',
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'rand': 1625289491289542947,
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'unix_epoch': 1741481111.19,
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'json_array': '[1,2,3,4]',
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'inserted_at': '2025-03-09 00:45:11'}]
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``` python
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assert rows[0]['rand'] != rows[1]['rand']
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```

‎apswutils/db.py‎

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@@ -1,5 +1,5 @@
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# This file is from sqlite-utils and copyright and license is the same as that project
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__all__ = ['Database', 'Queryable', 'Table', 'View']
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__all__ = ['Database', 'Queryable', 'Table', 'View', 'SQLExpr']
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from .utils import chunks, hash_record, suggest_column_types, types_for_column_types, column_affinity, find_spatialite, cursor_row2dict
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from collections import namedtuple
@@ -8,6 +8,7 @@
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from functools import cache
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import contextlib, datetime, decimal, inspect, itertools, json, os, pathlib, re, secrets, textwrap, binascii, uuid, logging
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import apsw, apsw.ext, apsw.bestpractice
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from fastcore.all import asdict
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logger = logging.getLogger('apsw')
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logger.setLevel(logging.ERROR)
@@ -3121,6 +3122,7 @@ def insert_all(
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num_records_processed = 0
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# Fix up any records with square braces in the column names
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records = fix_square_braces(records)
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records = remove_default_sql_exprs(records)
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# We can only handle a max of 999 variables in a SQL insert, so
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# we need to adjust the batch_size down if we have too many cols
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records = iter(records)
@@ -3715,9 +3717,20 @@ def fix_square_braces(records: Iterable[Dict[str, Any]]):
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else:
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yield record
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def remove_default_sql_exprs(records: Iterable[Dict[str, Any]]):
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for record in records:
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yield {k: v for k, v in asdict(record).items() if type(v) is not SQLExpr or not v.default}
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class SQLExpr():
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def __init__(self, expr, default=False): self.expr, self.default = expr, default
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def __str__(self): return f'SQLExpr: {self.expr}'
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__repr__ = __str__
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# Match anything that is not a single quote, then match anything that is an escaped single quote
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# (any number of times), then repeat the whole process
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_sql_string_datatype_matcher = re.compile(r"^'([^']*(\\')*)*'$")
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def _decode_default_value(value):
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if value.startswith("'") and value.endswith("'"):
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if _sql_string_datatype_matcher.match(value):
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# It's a string
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return value[1:-1]
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if value.isdigit():
@@ -3732,4 +3745,4 @@ def _decode_default_value(value):
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return float(value)
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except ValueError:
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pass
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return value
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return SQLExpr(value, True)

‎nbs/index.ipynb‎

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@@ -577,6 +577,157 @@
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"|sqlite3.dbapi2.OperationalError|apsw.SQLError|When an error is due to flawed SQL statements|\n",
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"|sqlite3.ProgrammingError|apsw.ConnectionClosedError|Caused by an improperly closed database file|\n"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"## Handling of default values"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Default values are handled as expected, including expression-based default values:"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [
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{
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"data": {
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"text/plain": [
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"<apsw.Cursor>"
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]
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},
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"execution_count": null,
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"metadata": {},
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"output_type": "execute_result"
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}
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],
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"source": [
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"db.execute(\"\"\"\n",
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"DROP TABLE IF EXISTS migrations;\n",
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"CREATE TABLE IF NOT EXISTS migrations (\n",
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" id INTEGER PRIMARY KEY,\n",
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" name TEXT DEFAULT 'foo',\n",
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" cexpr TEXT DEFAULT ('abra' || 'cadabra'),\n",
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" rand INTEGER DEFAULT (random()),\n",
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" unix_epoch FLOAT DEFAULT (unixepoch('subsec')),\n",
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" json_array JSON DEFAULT (json_array(1,2,3,4)),\n",
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" inserted_at DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL\n",
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");\n",
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"\"\"\")"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [
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{
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"data": {
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"text/plain": [
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"{'name': 'foo',\n",
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" 'cexpr': SQLExpr: 'abra' || 'cadabra',\n",
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" 'rand': SQLExpr: random(),\n",
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" 'unix_epoch': SQLExpr: unixepoch('subsec'),\n",
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" 'json_array': SQLExpr: json_array(1,2,3,4),\n",
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" 'inserted_at': SQLExpr: CURRENT_TIMESTAMP}"
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]
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},
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"execution_count": null,
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"metadata": {},
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"output_type": "execute_result"
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}
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],
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"source": [
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"migrations = Table(db, 'migrations')\n",
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"migrations.default_values"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"assert all([type(x) is SQLExpr for x in list(migrations.default_values.values())[1:]])"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [
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{
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"data": {
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"text/plain": [
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"<Table migrations (id, name, cexpr, rand, unix_epoch, json_array, inserted_at)>"
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]
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},
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"execution_count": null,
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"metadata": {},
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"output_type": "execute_result"
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}
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],
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"source": [
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"migrations.insert(dict(id=0))\n",
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"migrations.insert(dict(id=1))"
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]
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},
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{
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"cell_type": "markdown",
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"metadata": {},
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"source": [
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"Default expressions are executed independently for each row on row insertion:"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [
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{
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"data": {
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"text/plain": [
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"[{'id': 0,\n",
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" 'name': 'foo',\n",
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" 'cexpr': 'abracadabra',\n",
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" 'rand': 8201569685582150332,\n",
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" 'unix_epoch': 1741481111.188,\n",
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" 'json_array': '[1,2,3,4]',\n",
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" 'inserted_at': '2025-03-09 00:45:11'},\n",
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" {'id': 1,\n",
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" 'name': 'foo',\n",
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" 'cexpr': 'abracadabra',\n",
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" 'rand': 1625289491289542947,\n",
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" 'unix_epoch': 1741481111.19,\n",
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" 'json_array': '[1,2,3,4]',\n",
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" 'inserted_at': '2025-03-09 00:45:11'}]"
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]
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},
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"execution_count": null,
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"metadata": {},
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"output_type": "execute_result"
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}
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],
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"source": [
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"rows = list(migrations.rows)\n",
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"rows"
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]
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},
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{
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"cell_type": "code",
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"execution_count": null,
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"metadata": {},
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"outputs": [],
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"source": [
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"assert rows[0]['rand'] != rows[1]['rand']"
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]
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}
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],
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"metadata": {
@@ -587,5 +738,5 @@
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}
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},
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"nbformat": 4,
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"nbformat_minor": 2
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"nbformat_minor": 4
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}

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