probcomp/bayeslite

pass query parameters through to metamodel syntax

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#446 opened on Jul 12, 2016

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help wantedk days

Description

Currently we do not distinguish

CREATE GENERATOR g FOR p USING m ("foo")

from

CREATE GENERATOR g FOR p USING m ('foo')

which is not at the moment blocking anything (hence the stall of #410), but which may be worth fixing soon. Furthermore, passing a verbatim string through, e.g. to provide the source code in

CREATE GENERATOR g FOR p USING cgpm (
    MODEL x GIVEN y USING venturescript (source = 'assume x = 42; ...')
)

as we kludgily do in https://github.com/probcomp/bayeslite/blob/f3f27a584286a4f3f3a415a7935da6ea78bd9824/tests/test_vscgpm.py#L166-L179 with Python string formatting, is not easy to do reliably. That fragment just assumes no " appears in the VentureScript code, and abuses "..." quotation, which in SQL means names, with '...' meaning strings. No quotation should be necessary on the user's part -- it should be possible to do

bdb.execute('CREATE GENERATOR ... USING venturescript (source = ?) ...', (venturescript,))

and get the same intended effect reliably.

Contributor guide

Tech stack
pythonsql
Domain
database
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
PythonSQLBayeslite internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Look into the parsing of CREATE GENERATOR statements in Bayeslite. The issue mentions issue #410 which might have related discussion. The test file tests/test vscgpm.py shows a workaround. The goal is to distinguish between double quoted and single quoted strings and properly handle parameterized queries. Suggested approach: modify the parser to differentiate SQL string literals from identifiers when passing arguments to metamodel syntax.