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Fixed bug with keyset pagination over compound primary keys

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Closes #190
This commit is contained in:
Simon Willison 2018-03-29 22:10:09 -07:00
commit 31f63d1672
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5 changed files with 88 additions and 10 deletions
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28
datasette/utils.py
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@ -29,6 +29,34 @@ def path_from_row_pks(row, pks, use_rowid):
return ','.join(bits)
def compound_keys_after_sql(pks):
# Implementation of keyset pagination
# See https://github.com/simonw/datasette/issues/190
# For pk1/pk2/pk3 returns:
#
# ([pk1] > :p0)
# or
# ([pk1] = :p0 and [pk2] > :p1)
# or
# ([pk1] = :p0 and [pk2] = :p1 and [pk3] > :p2)
or_clauses = []
pks_left = pks[:]
while pks_left:
and_clauses = []
last = pks_left[-1]
rest = pks_left[:-1]
and_clauses = ['[{}] = :p{}'.format(
pk, i
) for i, pk in enumerate(rest)]
and_clauses.append('[{}] > :p{}'.format(
last, len(rest)
))
or_clauses.append('({})'.format(' and '.join(and_clauses)))
pks_left.pop()
or_clauses.reverse()
return '\n or\n'.join(or_clauses)
class CustomJSONEncoder(json.JSONEncoder):
def default(self, obj):
if isinstance(obj, sqlite3.Row):