Use Unicode-aware implementations of LOWER() and UPPER() in SQL queries (#865)

Fixes #840 by creating application-defined SQL functions
(https://www.sqlite.org/appfunc.html) for Unicode-aware implementations
of `LOWER()` and `UPPER()`. This uses
`String.prototype.toLower/UpperCase()` JS method.

I initially wanted to just redefine `LOWER()` and `UPPER()` but due to
[sql.js not supporting the definition of deterministic
functions](https://github.com/sql-js/sql.js/issues/551), I had to just
define them as separate functions and use that in the appropriate
places. It's probably better like that anyway...

packages/loot-core/src/platform/server/sqlite/index.electron.ts

@@ -84,7 +84,16 @@ export async function asyncTransaction(db, fn) {
 }
 
 export function openDatabase(pathOrBuffer) {
-  return new Database(pathOrBuffer);
+  let db = new Database(pathOrBuffer);
+  // Define Unicode-aware LOWER and UPPER implementation.
+  // This is necessary because better-sqlite3 uses SQLite build without ICU support.
+  db.function('UNICODE_LOWER', { deterministic: true }, arg =>
+    arg?.toLowerCase(),
+  );
+  db.function('UNICODE_UPPER', { deterministic: true }, arg =>
+    arg?.toUpperCase(),
+  );
+  return db;
 }
 
 export function closeDatabase(db) {

packages/loot-core/src/platform/server/sqlite/index.web.ts

@@ -151,36 +151,48 @@ export async function asyncTransaction(db, fn) {
 }
 
 export async function openDatabase(pathOrBuffer?: string | Buffer) {
+  let db = null;
   if (pathOrBuffer) {
     if (typeof pathOrBuffer !== 'string') {
-      return new SQL.Database(pathOrBuffer);
-    }
-
-    let path = pathOrBuffer;
-    if (path !== ':memory:') {
-      if (typeof SharedArrayBuffer === 'undefined') {
-        // @ts-expect-error FS missing in sql.js types
-        let stream = SQL.FS.open(SQL.FS.readlink(path), 'a+');
-        await stream.node.contents.readIfFallback();
-        // @ts-expect-error FS missing in sql.js types
-        SQL.FS.close(stream);
+      db = new SQL.Database(pathOrBuffer);
+    } else {
+      let path = pathOrBuffer;
+      if (path !== ':memory:') {
+        if (typeof SharedArrayBuffer === 'undefined') {
+          // @ts-expect-error FS missing in sql.js types
+          let stream = SQL.FS.open(SQL.FS.readlink(path), 'a+');
+          await stream.node.contents.readIfFallback();
+          // @ts-expect-error FS missing in sql.js types
+          SQL.FS.close(stream);
+        }
+
+        db = new SQL.Database(
+          // @ts-expect-error FS missing in sql.js types
+          path.includes('/blocked') ? path : SQL.FS.readlink(path),
+          // @ts-expect-error 2nd argument missed in sql.js types
+          { filename: true },
+        );
+        db.exec(`
+          PRAGMA journal_mode=MEMORY;
+          PRAGMA cache_size=-10000;
+        `);
       }
-
-      let db = new SQL.Database(
-        // @ts-expect-error FS missing in sql.js types
-        path.includes('/blocked') ? path : SQL.FS.readlink(path),
-        // @ts-expect-error 2nd argument missed in sql.js types
-        { filename: true },
-      );
-      db.exec(`
-      PRAGMA journal_mode=MEMORY;
-      PRAGMA cache_size=-10000;
-    `);
-      return db;
     }
   }
 
-  return new SQL.Database();
+  if (db === null) {
+    db = new SQL.Database();
+  }
+
+  // Define Unicode-aware LOWER and UPPER implementation.
+  // This is necessary because sql.js uses SQLite build without ICU support.
+  //
+  // Note that this function should ideally be created with a deterministic flag
+  // to allow SQLite to better optimize calls to it by factoring them out of inner loops
+  // but SQL.js does not support this: https://github.com/sql-js/sql.js/issues/551
+  db.create_function('UNICODE_LOWER', arg => arg?.toLowerCase());
+  db.create_function('UNICODE_UPPER', arg => arg?.toUpperCase());
+  return db;
 }
 
 export function closeDatabase(db) {

packages/loot-core/src/server/accounts/payees.js

@@ -4,7 +4,7 @@ export async function createPayee(description) {
   // Check to make sure no payee already exists with exactly the same
   // name
   let row = await db.first(
-    `SELECT id FROM payees WHERE LOWER(name) = ? AND tombstone = 0`,
+    `SELECT id FROM payees WHERE UNICODE_LOWER(name) = ? AND tombstone = 0`,
     [description.toLowerCase()],
   );
 

packages/loot-core/src/server/aql/compiler.js

@@ -564,7 +564,7 @@ const compileFunction = saveStack('function', (state, func) => {
     case '$lower': {
       validateArgLength(args, 1);
       let [arg1] = valArray(state, args, ['string']);
-      return typed(`LOWER(${arg1})`, 'string');
+      return typed(`UNICODE_LOWER(${arg1})`, 'string');
     }
 
     // integer/float functions

packages/loot-core/src/server/db/index.js

@@ -516,9 +516,10 @@ export async function getOrphanedPayees() {
 }
 
 export async function getPayeeByName(name) {
-  return first(`SELECT * FROM payees WHERE LOWER(name) = ? AND tombstone = 0`, [
-    name.toLowerCase(),
-  ]);
+  return first(
+    `SELECT * FROM payees WHERE UNICODE_LOWER(name) = ? AND tombstone = 0`,
+    [name.toLowerCase()],
+  );
 }
 
 export function insertPayeeRule(rule) {

upcoming-release-notes/865.md

+---
+category: Bugfix
+authors: [Jackenmen]
+---
+
+Fix case-insensitive matching of strings for uppercase letters from non-English alphabets