Hacktoberfest 2026: as issues que os mantenedores marcaram para outubro, abertas e boas para iniciantes. Ver issues do Hacktoberfest

JSON path equality against a non-string value: silently empty on MySQL, raises on PostgreSQL

Aberta
  • Algo errado?
#1,564 0 comentários 0 reações 0 responsáveis Ver no GitHub

Ninguém assumiu esta issue ainda.

Avaliação

Dificuldade
3/5
Tempo estimado
1-2 dias
Facilidade para iniciantes
75/100
Tipo de issue
Bug
Clareza
Claramente especificada
Status de atividade
Ativa
Stack de tecnologia
mysql, postgresql, python
Domínio
databases

Direção de pesquisa

Start in condition.py around prep_value at line 336, then trace adapter.json_path_expr for the MySQL and PostgreSQL implementations. Reproduce the listed restrictions against both backends and add regression coverage for string, integer, and boolean values. Done means JSON-path comparisons behave consistently across backends and never silently return wrong rows.

Escrita pelo modelo de indexação a partir do texto da issue.

Descrição

bug

Table & {"json_attr.field": value} only behaves correctly when value is a string. A Python bool returns the wrong answer on MySQL and raises on PostgreSQL; a Python int raises on PostgreSQL.

Sibling of #1563 — same root (JSON extraction yields text), different side: that one is the :type annotation on projection, this one is the Python value on restriction.

Repro

@schema
class E(dj.Manual):
    definition = """
    name : varchar(32)
    ---
    s : json
    """
E.insert([
    {"name": "a", "s": {"vendor": "Acme",  "ch": 64, "cal": True}},
    {"name": "b", "s": {"vendor": "Other", "ch": 16, "cal": False}},
])

Each row should select ['a']:

restriction MySQL 8.0 postgres:15
& {"s.vendor": "Acme"} ['a'] ['a']
& {"s.ch": 64} ['a'] UndefinedFunction: operator does not exist: text = integer
& {"s.ch": "64"} ['a'] ['a']
& {"s.cal": True} [] UndefinedFunction: operator does not exist: text = boolean
& {"s.cal": "true"} ['a'] ['a']

The MySQL boolean row is the serious one: no error, no rows, and the natural reading of an empty result is "nothing is calibrated."

Cause

adapter.json_path_expr yields json_value(...) / jsonb_extract_path_text(...), both of which return text. prep_value (condition.py:336) then renders the Python value by its own type, so the comparison becomes text = <non-text>:

  • PostgreSQL refuses the comparison outright.
  • MySQL coerces for numerics, which is why 64 happens to work, but compares the extracted true against 1 for a bool and matches nothing.

The asymmetry is invisible to a user: the same expression is correct, wrong, or an error depending on the value's Python type and the backend.

Suggested fix

On the JSON-path branch of prep_value, render the comparison value as text — or cast the extraction to the value's type — so that True, 64 and "Acme" all behave the same way on both backends.

Whichever way, a bool must not silently match nothing. If a given comparison cannot be made portable, raising is acceptable; returning the wrong rows is not.

Documentation

This is almost certainly why tutorials/advanced/json-type.ipynb teaches "Filtering on JSON Content — fetch then filter in Python" and lists "Filter in Python" as an inherent property of JSON in its Design Guidelines. Server-side filtering does work, with the value passed as a string; the tutorial's advice reads as a limitation of the type rather than of this behavior. Worth revisiting together.

Linguagem predominante
Python
Estrelas
197
Forks
98
Merge médio
23h 9min
PRs com merge (30d)
6

Preparar o ambiente

Primeiros passos

  1. Leia a issue inteira e depois o guia de contribuição do projeto.
  2. Comente na issue dizendo que vai assumir — evita que duas pessoas façam o mesmo trabalho.
  3. Faça um fork do repositório e trabalhe em uma branch.
  4. Abra um pull request que referencie o número da issue.

Mais de datajoint/datajoint-python

Todas as issues de datajoint/datajoint-python

Issues semelhantes

Mais issues de Python

Receba novas issues na sua caixa de entrada

Um resumo curto de issues do GitHub para quem está começando.