Fix SQLite NULL from ALTER TABLE ADD COLUMN returns proper defaults - #72
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…lt values Adding a new field to a record type in a source relation and running without a migrate block left SQL NULL for existing rows. read_sql_column returned a raw null pointer for non-nullable types, and even Maybe fields read back as null instead of Nothing. Fix: read_sql_column now returns proper default values when the SQL column is NULL: - Int: 0 (backfilled as TEXT '0' with COLLATE KNOT_INT) - Text: empty string - Bool: False - Float: 0.0 - tag (enum): panics with actionable message pointing at migrate block - Maybe: Nothing (NULL naturally maps to Nothing) - json: Nothing (documented tradeoff — can't distinguish Maybe from other json-column shapes without descriptor format change) 7 new tests covering scalar defaults, Maybe→Nothing, SQLite backfill, nested-child-table fields, enum error, and ADT invariants. cargo test -p knot-runtime: 156 passed.
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Summary
Adding a new field to a record type in a source relation and running without a migrate block left SQL NULL for existing rows.
read_sql_columnreturned a raw null pointer for non-nullable types, and evenMaybefields read back as null instead ofNothing.Fix
read_sql_columnnow returns proper default values when the SQL column is NULL:'0'with COLLATE KNOT_INT)migrateblockTests
7 new tests: scalar defaults, Maybe→Nothing, SQLite backfill typing, nested-child-table fields, enum error, ADT invariants.
Verification
End-to-end repro:
{name, age}grown to{name, age, nickname: Maybe Text, score: Int, active: Bool}with no migrate block. Before: null pointers. Now:[{active: False, age: 30, name: "Alice", nickname: Nothing, score: 0}, ...]