buildSelection() — drizzle-orm Function Reference

Source Code

drizzle-orm/src/mysql-core/dialect.ts lines 187–253

	private buildSelection(
		fields: SelectedFieldsOrdered,
		{ isSingleTable = false }: { isSingleTable?: boolean } = {},
	): SQL {
		const columnsLen = fields.length;

		const chunks = fields
			.flatMap(({ field }, i) => {
				const chunk: SQLChunk[] = [];

				if (is(field, SQL.Aliased) && field.isSelectionField) {
					chunk.push(sql.identifier(field.fieldAlias));
				} else if (is(field, SQL.Aliased) || is(field, SQL)) {
					const query = is(field, SQL.Aliased) ? field.sql : field;

					if (isSingleTable) {
						chunk.push(
							new SQL(
								query.queryChunks.map((c) => {
									if (is(c, MySqlColumn)) {
										return sql.identifier(this.casing.getColumnCasing(c));
									}
									return c;
								}),
							),
						);
					} else {
						chunk.push(query);
					}

					if (is(field, SQL.Aliased)) {
						chunk.push(sql` as ${sql.identifier(field.fieldAlias)}`);
					}
				} else if (is(field, Column)) {
					if (isSingleTable) {
						chunk.push(sql.identifier(this.casing.getColumnCasing(field)));
					} else {
						chunk.push(field);
					}
				} else if (is(field, Subquery)) {
					const entries = Object.entries(field._.selectedFields) as [string, SQL.Aliased | Column | SQL][];

					if (entries.length === 1) {
						const entry = entries[0]![1];

						const fieldDecoder = is(entry, SQL)
							? entry.decoder
							: is(entry, Column)
							? { mapFromDriverValue: (v: any) => entry.mapFromDriverValue(v) }
							: entry.sql.decoder;

						if (fieldDecoder) {
							field._.sql.decoder = fieldDecoder;
						}
					}
					chunk.push(field);
				}

				if (i < columnsLen - 1) {
					chunk.push(sql`, `);
				}

				return chunk;
			});

		return sql.join(chunks);
	}