joaoh82 / rust_sqlite / 25093849524

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push

github

Committed by web-flow

Commit Message

Phase 7e: JSON column type + path queries (#54)

Adds the JSON storage class and four path-aware query functions, closing
the second of Phase 7's two storage primitives (the first was VECTOR(N)
in 7a). Shape mirrors SQLite's JSON1 extension — JSON values store as
canonical UTF-8 text, validated via `serde_json::from_str` at INSERT and
UPDATE time. Phase 7 plan Q3 originally proposed bincoded `serde_json::
Value`, but bincode was removed from the engine in Phase 3c (cell-based
encoding replaced it); rather than re-add bincode for one column type,
JSON-as-text matches SQLite's choice and reuses the existing Text storage
path. Q3 in `docs/phase-7-plan.md` records the scope correction inline.

Engine surface:

- `DataType::Json` variant alongside `Vector(N)`. `JSONB` parses as an
  alias (Postgres convention; both store as text in our case).
- INSERT/UPDATE on a JSON column runs `serde_json::from_str::<Value>`;
  malformed JSON is rejected with `Type mismatch: expected JSON for
  column 'foo': <serde error>`. NULLs pass through untouched.
- UNIQUE on a JSON column treats the value as raw text (string equality
  on the canonical form).
- `table_to_create_sql` round-trips JSON columns; `build_empty_table`,
  `Row::Text(BTreeMap::new())` storage, and the `clone_datatype` helpers
  in `executor.rs` and `pager/mod.rs` all gained the new arm.

Functions (executor.rs, ~370 LOC):

- `json_extract(json[, path])` — walks the path, returns the resolved
  node coerced to the closest SQL type. Strings → TEXT, numbers →
  INTEGER/REAL, booleans → BOOLEAN, `null` → NULL, composites
  (object/array) → canonical JSON text.
- `json_type(json[, path])` — returns one of `'object'`, `'array'`,
  `'string'`, `'integer'`, `'real'`, `'true'`, `'false'`, `'null'`.
- `json_array_length(json[, path])` — element count; errors if the
  resolved node isn't an array.
- `json_object_keys(json[, path])` — keys as a JSON-array text in
  insertion order (e.g. `'["a","b","c"]'`). Diverges f... (continued)

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154 of 210 new or added lines in 5 files covered. (73.33%)

227 existing lines in 3 files now uncovered.

5382 of 7795 relevant lines covered (69.04%)

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