126 lines
3.7 KiB
D
126 lines
3.7 KiB
D
module util.sqlite;
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import slf4d;
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import handy_httpd.components.optional;
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import d2sqlite3;
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/**
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* Tries to find a single row from a database.
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* Params:
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* db = The database to use.
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* query = The query to execute.
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* resultMapper = A function to map rows to the desired result type.
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* args = Arguments for the query.
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* Returns: An optional result.
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*/
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Optional!T findOne(T, Args...)(Database db, string query, T function(Row) resultMapper, Args args) {
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Statement stmt = db.prepare(query);
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stmt.bindAll(args);
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ResultRange result = stmt.execute();
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if (result.empty) return Optional!T.empty;
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return Optional!T.of(resultMapper(result.front));
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}
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/**
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* Tries to find a single entity by its id, selecting all properties.
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* Params:
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* db = The database to use.
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* table = The table to select from.
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* resultMapper = A function to map rows to the desired result type.
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* id = The entity's id.
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* Returns: An optional result.
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*/
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Optional!T findById(T)(Database db, string table, T function(Row) resultMapper, ulong id) {
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Statement stmt = db.prepare("SELECT * FROM " ~ table);
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stmt.bind(1, id);
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ResultRange result = stmt.execute();
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if (result.empty) return Optional!T.empty;
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return Optional!T.of(resultMapper(result.front));
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}
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/**
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* Finds a list of records from a database.
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* Params:
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* db = The database to use.
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* query = The query to execute.
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* resultMapper = A function to map rows to the desired result type.
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* args = Arguments for the query.
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* Returns: A list of results.
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*/
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T[] findAll(T, Args...)(Database db, string query, T function(Row) resultMapper, Args args) {
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Statement stmt = db.prepare(query);
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stmt.bindAll(args);
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import std.algorithm : map;
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import std.array : array;
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return stmt.execute().map!(r => resultMapper(r)).array;
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}
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/**
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* Determines if at least one record exists.
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* Params:
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* db = The database to use.
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* query = The query to execute.
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* args = The arguments for the query.
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* Returns: True if at least one record is returned, or false if not.
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*/
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bool exists(Args...)(Database db, string query, Args args) {
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Statement stmt = db.prepare(query);
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stmt.bindAll(args);
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return !stmt.execute().empty();
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}
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/**
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* Performs an update (UPDATE/INSERT/DELETE).
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* Params:
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* db = The database to use.
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* query = The query to execute.
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* args = The arguments for the query.
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* Returns: The number of rows that were affected.
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*/
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int update(Args...)(Database db, string query, Args args) {
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Statement stmt = db.prepare(query);
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stmt.bindAll(args);
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stmt.execute();
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return db.changes();
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}
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/**
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* Deletes an entity from a table.
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* Params:
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* db = The database to use.
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* table = The table to delete from.
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* id = The id of the entity to delete.
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*/
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void deleteById(Database db, string table, ulong id) {
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Statement stmt = db.prepare("DELETE FROM " ~ table ~ " WHERE id = ?");
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stmt.bind(1, id);
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stmt.execute();
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}
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/**
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* Wraps a given delegate block of code in an SQL transaction, so that all
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* operations will be committed at once when done. If an exception is thrown,
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* then the changes will be rolled back.
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* Params:
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* db = The database to use.
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* dg = The delegate block of code to run in the transaction.
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* Returns: The return value of the delegate, if the delegate does indeed
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* return something.
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*/
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T doTransaction(T)(Database db, T delegate() dg) {
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try {
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db.begin();
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static if (is(T : void)) {
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dg();
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} else {
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T result = dg();
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}
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db.commit();
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static if (!is(T : void)) return result;
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} catch (Exception e) {
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error("Rolling back transaction due to exception.", e);
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db.rollback();
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throw e;
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}
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}
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