sqlite::json / sqlite::fts | vsqlite++ Reference

Provides high-level helpers for SQLite's JSON1 and FTS5 extensions: compose JSON paths, build SQL snippets, detect availability, and register helper SQL functions.

Use cases

Keep JSON path building type-safe—no stray quotes or typos when drilling into deeply nested structures.
Detect feature availability at runtime so you can gracefully fall back on builds compiled without JSON1/FTS5.
Install deterministic helper functions exactly once per connection to keep SQL migrations tidy.

Example usage

SELECT json_extract(blob, '$.user.email') FROM events;

auto path = sqlite::json::path().key("user").key("email");
auto expr = sqlite::json::extract_expression("events.blob", path);

sqlite::query q{db,
    "SELECT " + expr + " AS email "
    "FROM events "
    "WHERE " + sqlite::fts::match_expression("events_fts") + " "
    "ORDER BY fts_rank(matchinfo(events_fts)) DESC"
};
sqlite::json::register_contains_function(db);
sqlite::fts::register_rank_function(db);

These helpers just spit out SQL strings, so you can drop them straight into migrations, ORMs, or whatever query builder you already use.

`sqlite::json::path_builder`

Member	Description
`path_builder()`	Initializes the internal string with `"$"`.
`path_builder& key(std::string_view segment)`	Appends `.segment` (quoting automatically when needed).
`path_builder& index(std::size_t idx)`	Appends array access (`[idx]`).
`std::string const& str() const noexcept`	Returns the accumulated JSON path.

inline path_builder path() returns a new builder rooted at $.

JSON utilities

Function	Description
`std::string extract_expression(std::string_view json_expr, path_builder const& path)`	Produces `"json_extract(json_expr, 'path')"` snippets.
`std::string contains_expression(std::string_view json_expr, path_builder const& path, std::string_view value_expr)`	Returns an equality comparison between a JSON slot and `value_expr`.
`bool json::available(connection&)`	Checks whether JSON1 is compiled into the current connection.
`void json::register_contains_function(connection&, std::string_view function_name = "json_contains_value")`	Installs a deterministic scalar function that tests whether a JSON path equals the given value.

FTS utilities

Function	Description
`bool fts::available(connection&)`	Verifies that FTS5 APIs are present.
`std::string fts::match_expression(std::string_view column_or_table, std::string_view query_expr = "?")`	Generates `"column MATCH query"` fragments.
`void fts::register_rank_function(connection&, std::string_view function_name = "fts_rank")`	Registers a simple ranking function that counts matched phrases.