issue_comments

Needs tests and documentation.

Prototype: ```diff diff --git a/sqlite_utils/cli.py b/sqlite_utils/cli.py index 8255b56..0a3693e 100644 --- a/sqlite_utils/cli.py +++ b/sqlite_utils/cli.py @@ -2583,7 +2583,11 @@ def generate_convert_help(): """ ).strip() recipe_names = [ - n for n in dir(recipes) if not n.startswith("") and n not in ("json", "parser") + n + for n in dir(recipes) + if not n.startswith("_") + and n not in ("json", "parser") + and callable(getattr(recipes, n)) ] for name in recipe_names: fn = getattr(recipes, name) diff --git a/sqlite_utils/recipes.py b/sqlite_utils/recipes.py index 6918661..569c30d 100644 --- a/sqlite_utils/recipes.py +++ b/sqlite_utils/recipes.py @@ -1,17 +1,38 @@ from dateutil import parser import json

+IGNORE = object() +SET_NULL = object()

-def parsedate(value, dayfirst=False, yearfirst=False): + +def parsedate(value, dayfirst=False, yearfirst=False, errors=None): "Parse a date and convert it to ISO date format: yyyy-mm-dd" - return ( - parser.parse(value, dayfirst=dayfirst, yearfirst=yearfirst).date().isoformat() - ) + try: + return ( + parser.parse(value, dayfirst=dayfirst, yearfirst=yearfirst) + .date() + .isoformat() + ) + except parser.ParserError: + if errors is IGNORE: + return value + elif errors is SET_NULL: + return None + else: + raise

-def parsedatetime(value, dayfirst=False, yearfirst=False): +def parsedatetime(value, dayfirst=False, yearfirst=False, errors=None): "Parse a datetime and convert it to ISO datetime format: yyyy-mm-ddTHH:MM:SS" - return parser.parse(value, dayfirst=dayfirst, yearfirst=yearfirst).isoformat() + try: + return parser.parse(value, dayfirst=dayfirst, yearfirst=yearfirst).isoformat() + except parser.ParserError: + if errors is IGNORE: + return value + elif errors is SET_NULL: + return None + else: + raise

def jsonsplit(value, delimiter=",", type=str): ```

This is quite nice: % sqlite-utils convert test-dates.db dates date "r.parsedate(value, errors=r.IGNORE)" [####################################] 100% % sqlite-utils rows test-dates.db dates [{"id": 1, "date": "2016-03-15"}, {"id": 2, "date": "2016-03-16"}, {"id": 3, "date": "2016-03-17"}, {"id": 4, "date": "2016-03-18"}, {"id": 5, "date": "2016-03-19"}, {"id": 6, "date": "2016-03-20"}, {"id": 7, "date": "2016-03-21"}, {"id": 8, "date": "2016-03-22"}, {"id": 9, "date": "2016-03-23"}, {"id": 10, "date": "//"}, {"id": 11, "date": "2016-03-25"}, {"id": 12, "date": "2016-03-26"}, {"id": 13, "date": "2016-03-27"}, {"id": 14, "date": "2016-03-28"}, {"id": 15, "date": "2016-03-29"}, {"id": 16, "date": "2016-03-30"}, {"id": 17, "date": "2016-03-31"}, {"id": 18, "date": "2016-04-01"}] % sqlite-utils convert test-dates.db dates date "r.parsedate(value, errors=r.SET_NULL)" [####################################] 100% % sqlite-utils rows test-dates.db dates [{"id": 1, "date": "2016-03-15"}, {"id": 2, "date": "2016-03-16"}, {"id": 3, "date": "2016-03-17"}, {"id": 4, "date": "2016-03-18"}, {"id": 5, "date": "2016-03-19"}, {"id": 6, "date": "2016-03-20"}, {"id": 7, "date": "2016-03-21"}, {"id": 8, "date": "2016-03-22"}, {"id": 9, "date": "2016-03-23"}, {"id": 10, "date": null}, {"id": 11, "date": "2016-03-25"}, {"id": 12, "date": "2016-03-26"}, {"id": 13, "date": "2016-03-27"}, {"id": 14, "date": "2016-03-28"}, {"id": 15, "date": "2016-03-29"}, {"id": 16, "date": "2016-03-30"}, {"id": 17, "date": "2016-03-31"}, {"id": 18, "date": "2016-04-01"}]

I'm going to try the errors=r.IGNORE option and see what that looks like once implemented.

I think the options here should be:

• On error, raise an exception and revert the transaction (the current default)
• On error, leave the value as-is
• On error, set the value to None

These need to be indicated by parameters to the r.parsedate() function.

Some design options:

• ignore=True to ignore errors - but how does it know if it should leave the value or set it to None? This is similar to other ignore=True parameters elsewhere in the Python API.
• errors="ignore", errors="set-null" - I don't like magic string values very much, but this is similar to Python's str.encode(errors=) mechanism
• errors=r.IGNORE - using constants, which at least avoids magic strings. The other one could be errors=r.SET_NULL
• error=lambda v: None or error=lambda v: v - this is a bit confusing though, introducing another callback that gets to have a go at converting the error if the first callback failed? And what happens if that lambda itself raises an error?

I confirmed that if it fails for any value ALL values are left alone, since it runs in a transaction.

Here's the code that does that:

https://github.com/simonw/sqlite-utils/blob/433813612ff9b4b501739fd7543bef0040dd51fe/sqlite_utils/db.py#L2523-L2526

Then I ran this to convert 2016-03-27 etc to 2016/03/27 so I could see which ones were later converted:

sqlite-utils convert test-dates.db dates date 'value.replace("-", "/")'

Generating a test database using a pattern from https://www.geekytidbits.com/date-range-table-sqlite/ sqlite-utils create-database test-dates.db sqlite-utils create-table test-dates.db dates id integer date text --pk id sqlite-utils test-dates.db "WITH RECURSIVE cnt(x) AS ( SELECT 0 UNION ALL SELECT x+1 FROM cnt LIMIT (SELECT ((julianday('2016-04-01') - julianday('2016-03-15'))) + 1) ) insert into dates (date) select date(julianday('2016-03-15'), '+' || x || ' days') as date FROM cnt;" After running that: % sqlite-utils rows test-dates.db dates [{"id": 1, "date": "2016-03-15"}, {"id": 2, "date": "2016-03-16"}, {"id": 3, "date": "2016-03-17"}, {"id": 4, "date": "2016-03-18"}, {"id": 5, "date": "2016-03-19"}, {"id": 6, "date": "2016-03-20"}, {"id": 7, "date": "2016-03-21"}, {"id": 8, "date": "2016-03-22"}, {"id": 9, "date": "2016-03-23"}, {"id": 10, "date": "2016-03-24"}, {"id": 11, "date": "2016-03-25"}, {"id": 12, "date": "2016-03-26"}, {"id": 13, "date": "2016-03-27"}, {"id": 14, "date": "2016-03-28"}, {"id": 15, "date": "2016-03-29"}, {"id": 16, "date": "2016-03-30"}, {"id": 17, "date": "2016-03-31"}, {"id": 18, "date": "2016-04-01"}] Then to make one of them invalid:

sqlite-utils test-dates.db "update dates set date = '//' where id = 10"