Named parameters

[adespawn]

This PR introduces support for named parameters in prepared (queries/statements). By reusing handling logic (code in utils.js), I aim to keep the API compatibility with DSx driver.

At a later point, we can have a discussion about whether we want to still accept case-insensitive parameters, or do we want to enforce case sensitivity.

This does not fully close​ #99, as the DSx driver had support for named parameters in unprepared (queries/statements) in some special cases (when type hints were used in a specific way). Such support will be added in the following PRs.

[Copilot]

Pull request overview

Adds support for named parameters for prepared statements by retrieving prepared variable metadata (types + variable names) from the Rust layer and reusing the existing parameter-adaptation logic in lib/utils.js, aligning behavior with the DataStax Node.js driver.

Changes:

• Re-enabled/added integration tests covering named parameters for prepared execute() and prepared batch().
• Updated Rust prepareStatement to return (type, variableName) pairs and introduced PreparedInfo on the JS side to hold prepared query metadata.
• Wired named-parameter detection/adaptation into prepared execution paths (including concurrent execution).

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
test/integration/supported/client-execute-prepared-tests.js	Re-enables prepared named-parameter integration tests.
test/integration/supported/client-batch-tests.js	Re-enables batch named-parameter integration tests.
src/session.rs	Changes prepare_statement to return type + variable name tuples to JS.
src/requests/request.rs	Extracts variable names alongside types from prepared metadata.
lib/utils.js	Adapts named parameters using PreparedInfo (types + column names).
lib/prepared.js	New PreparedInfo wrapper to build prepared metadata from Rust prepareStatement().
lib/new-utils.js	Adds isNamedParameters() helper for consistent validation/erroring.
lib/concurrent/index.js	Updates concurrent executor to cache/use PreparedInfo.
lib/client.js	Integrates PreparedInfo and named-param adaptation into prepared execution and paging paths.

Comments suppressed due to low confidence (1)

lib/client.js:733

• #rustyBatch() can still receive params as an object (the public batch() signature allows (Array|Object)?), but when shouldBePrepared is false those objects are passed directly into encodeParams(), which expects an array (params.length) and will throw a low-level TypeError. Add the same validation used in execute()/#rustyPaged() (e.g., reuse isNamedParameters() or explicitly throw ArgumentError when params is a non-array object and prepare is not enabled) to fail fast with a clear error message.

                typeof element === "string" ? element : element.query;
            let params = element.params || [];
            let types;

            if (!statement) {
                throw new errors.ArgumentError(`Invalid query at index ${i}`);
            }

            if (shouldBePrepared) {
                let prepared = preparedCache.getElement(statement);
                if (!prepared) {
                    prepared = await PreparedInfo.create(
                        statement,
                        this.rustClient,
                    );
                    preparedCache.storeElement(statement, prepared);
                }
                types = prepared.types;
                statement = prepared.query;

                if (params && !Array.isArray(params)) {
                    params = utils.adaptNamedParamsPrepared(params, prepared);
                }
            } else {
                types = hints[i] || [];
            }

            if (params) {
                params = encodeParams(types, params, this.#encoder);
            }

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[wprzytula]

I'd prefer to review this only after @nikagra. Is this OK?