What is FIQL?

From the FIQL draft [ https://tools.ietf.org/html/draft-nottingham-atompub-fiql-00 ]:

The Feed Item Query Language (FIQL, pronounced “fickle”) is a simple but flexible, URI-friendly syntax for expressing filters across the entries in a syndicated feed.

How does FIQL work?

A Feed Item Query string looks something like this:

last_name==foo*,(age=lt=55;age=gt=5)

The above query string is looking for all records with last_name starting with “foo” OR age less than 55 AND greater than 5. The parentheses in the query work the same as they do in any logical expression.

Installing fiql_parser

From PyPi

$ pip install fiql-parser

From source (tar.gz or checkout)

Unpack the archive, enter the fiql_parser directory and run:

$ python setup.py install

Using fiql_parser

Currently the functionality is pretty limited so there isn’t a lot to say on how to use it.

Parsing a FIQL formatted string

from fiql_parser import parse_str_to_expression

fiql_str = "last_name==foo*,(age=lt=55;age=gt=5)"
expression = parse_str_to_expression(fiql_str)

# to_python()'s output changed with Version 0.11.
print expression.to_python()
# Output of above would be:
['OR',
    ('last_name', '==', 'foo*'),
    ['AND',
        ('age', '<', '55'),
        ('age', '>', '5'),
    ]
]

Building an Expression

Method One

from fiql_parser import (Expression, Constraint, Operator)

expression = Expression()
expression.add_element(Constraint('last_name', '==', 'foo*'))
expression.add_element(Operator(','))
sub_expression = Expression()
sub_expression.add_element(Constraint('age', '=lt=', '55'))
sub_expression.add_element(Operator(';'))
sub_expression.add_element(Constraint('age', '=gt=', '5'))
expression.add_element(sub_expression)

print str(expression)
# Output of above would be:
"last_name==foo*,(age=lt=55;age=gt=5)"

Method Two (Changed in Version 0.11)

from fiql_parser import Constraint

expression = Constraint('last_name', '==', 'foo*').op_or(
        Constraint('age', '=lt=', '55').op_and(
                Constraint('age', '=gt=', '5')
            )
        )

fiql_str = str(expression)
# Output of above would be:
"last_name==foo*,(age=lt=55;age=gt=5)"