Multi-line rules

[langston-barrett]

Bellybutton doesn't like this:

  filter_by:
    description: Use SQLAlchemy's filter_by for concision
    # Find calls to "filter" that:
    # 
    # - are chained after a call to "query" with one argument,
    # - have one argument,
    # - which is an equality comparison
    #   * which has a LHS which is an attribute access on a name
    expr: >
      //Call[ ./func/Attribute[ @attr='filter'
                                and ./value/Call[./func/Attribute[@attr='query']
                                and ./args[count(child::*) = 1]]
                              ]
             and ./args[count(child::*) = 1]
             and ./args/Compare[ ./ops/Eq
                                 and ./left/Attribute[ @attr != 'attributes'
                                                       and ./value/Name
                                                     ]
                               ]
            ]
    example: |
      session.query(Model).filter(Model.attr == baz)
    instead: |
      session.query(Model).filter_by(attr = baz)
    settings: *all_files

it says:

ERROR: /x/frontend/.bellybutton.yml, rule `filter_by`: 'str' object has no attribute 'match'

It works fine if you inline expr, but this is a pain because expr is huge:

    expr: //Call[./func/Attribute[ @attr='filter' and ./value/Call[./func/Attribute[@attr='query'] and ./args[count(child::*) = 1]]] and ./args[count(child::*) = 1] and ./args/Compare[ ./ops/Eq and ./left/Attribute[ @attr != 'attributes' and ./value/Name]]]

This is version 0.3.0.

[hchasestevens]

Hi @langston-barrett ,

Thanks for raising! bellybutton relies on the first characters of the expr being //, to know to parse the value as an XPath expression. I will not close this ticket, since you (rightly) point out the annoyance of not being able to use the standard YAML multi-line syntax, however, I think you should be able to instead do:

  filter_by:
    description: Use SQLAlchemy's filter_by for concision
    expr:
      //Call[ ./func/Attribute[ @attr='filter'
                                and ./value/Call[./func/Attribute[@attr='query']
                                and ./args[count(child::*) = 1]]
                              ]
             and ./args[count(child::*) = 1]
             and ./args/Compare[ ./ops/Eq
                                 and ./left/Attribute[ @attr != 'attributes'
                                                       and ./value/Name
                                                     ]
                               ]
            ]
    example: |
      session.query(Model).filter(Model.attr == baz)
    instead: |
      session.query(Model).filter_by(attr = baz)
    settings: *all_files

and have it work (or, at least, this is how I typically format my .bellybutton.yml files). Please let me know if this helps!

• Chase

[langston-barrett]

@hchasestevens Thanks for the quick reply! That works perfectly. Feel free to keep open if you feel like supporting YAML multi-line string syntax, but I'm satisfied as long as I can write the rules readably.