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Description:

sqlparser

sqlparser #
SQL parser and static analyzer written in Dart. At the moment, this library targets the
SQLite dialect only.
Features #
This library aims to support every SQLite feature, which includes parsing and detailed
static analysis.
We can resolve what type a column in a SELECT statement has, infer types for variables,
find semantic errors and more.
This library supports most SQLite features:

DQL: Full support, including joins, group by, nested and compound selects, WITH clauses
and window functions
DDL: Supports CREATE TABLE statements, including advanced features like foreign keys or
virtual tables (when a matching module like fts5 is enabled). This library also supports
CREATE TRIGGER and CREATE INDEX statements.

Using the parser #
To obtain an abstract syntax tree from an SQL statement, use SqlEngine.parse.
import 'package:sqlparser/sqlparser.dart';

final engine = SqlEngine();
final result = engine.parse('''
SELECT f.* FROM frameworks f
INNER JOIN uses_language ul ON ul.framework = f.id
INNER JOIN languages l ON l.id = ul.language
WHERE l.name = 'Dart'
ORDER BY f.name ASC, f.popularity DESC
LIMIT 5 OFFSET 5 * 3
''');
// result.rootNode contains the select statement in tree form
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Analysis #
Given information about all tables and an SQL statement, this library can:

Determine which result columns a query is going to have, including types and nullability
Make an educated guess about what type the variables in the query should have (it's not really
possible to be 100% accurate about this because SQLite is very flexible at types, but this library
gets it mostly right)
Issue basic warnings about queries that are syntactically valid but won't run (references unknown
tables / columns, uses undefined functions, etc.)

To use the analyzer, first register all known tables via SqlEngine.registerTable. Then,
SqlEngine.analyze(sql) gives you an AnalysisContext which contains an annotated AST and information
about errors. The type of result columns and expressions can be inferred by using
AnalysisContext.typeOf(). Here's an example:
final id = TableColumn('id', const ResolvedType(type: BasicType.int));
final content = TableColumn('content', const ResolvedType(type: BasicType.text));
final demoTable = Table(
name: 'demo',
resolvedColumns: [id, content],
);
final engine = SqlEngine()..registerTable(demoTable);

final context =
engine.analyze('SELECT id, d.content, *, 3 + 4 FROM demo AS d');

final select = context.root as SelectStatement;
final resolvedColumns = select.resolvedColumns;

resolvedColumns.map((c) => c.name); // id, content, id, content, 3 + 4
resolvedColumns.map((c) => context.typeOf(c).type.type); // int, text, int, text, int, int
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But why? #
Drift, a persistence library for Dart apps, uses this
package to generate type-safe methods from SQL.
Thanks #

To Bob Nystrom for his amazing "Crafting Interpreters"
book, which was incredibly helpful when writing the parser.