Added ability to receive updates from sqlite3_update_hook

closes TryGhost#419

- this adds support for a `change` event which forwards events arising
  from `sqlite3_update_hook`

Author: soukand

lib/sqlite3.js

@@ -146,7 +146,7 @@ Statement.prototype.map = function() {
 
 let isVerbose = false;
 
-const supportedEvents = [ 'trace', 'profile', 'insert', 'update', 'delete' ];
+const supportedEvents = [ 'trace', 'profile', 'change' ];
 
 Database.prototype.addListener = Database.prototype.on = function(type) {
     const val = EventEmitter.prototype.addListener.apply(this, arguments);

src/database.cc

@@ -387,6 +387,11 @@ Napi::Value Database::Configure(const Napi::CallbackInfo& info) {
         Baton* baton = new LimitBaton(db, handle, id, value);
         db->Schedule(SetLimit, baton);
     }
+    else if (info[0].StrictEquals(Napi::String::New(env, "change"))) {
+        Napi::Function handle;
+        Baton* baton = new Baton(db, handle);
+        db->Schedule(RegisterUpdateCallback, baton);
+    }
     else {
         Napi::TypeError::New(env, (StringConcat(
 #if V8_MAJOR_VERSION > 6
@@ -556,12 +561,13 @@ void Database::UpdateCallback(Database *db, UpdateInfo* i) {
     Napi::HandleScope scope(env);
 
     Napi::Value argv[] = {
+        Napi::String::New(env, "change"),
         Napi::String::New(env, sqlite_authorizer_string(info->type)),
         Napi::String::New(env, info->database.c_str()),
         Napi::String::New(env, info->table.c_str()),
         Napi::Number::New(env, info->rowid),
     };
-    EMIT_EVENT(db->Value(), 4, argv);
+    EMIT_EVENT(db->Value(), 5, argv);
 }
 
 Napi::Value Database::Exec(const Napi::CallbackInfo& info) {
@@ -762,4 +768,8 @@ void Database::RemoveCallbacks() {
         debug_profile->finish();
         debug_profile = NULL;
     }
+    if (update_event) {
+        update_event->finish();
+        update_event = NULL;
+    }
 }

test/update_hook.test.js

@@ -0,0 +1,75 @@
+var sqlite3 = require('..');
+var assert = require('assert');
+
+describe('update_hook', function() {
+    var db;
+
+    beforeEach(function(done) {
+        db = new sqlite3.Database(':memory:', function(err) {
+            if (err) return done(err);
+
+            db.run("CREATE TABLE update_hooks_test (id int PRIMARY KEY, value text)", done);
+        });
+    });
+
+    it('emits insert event on inserting data to table', function(done) {
+        db.addListener('change', function(eventType, database, table, rowId) {
+            assert.equal(eventType, 'insert');
+            assert.equal(database, 'main');
+            assert.equal(table, 'update_hooks_test');
+            assert.equal(rowId, 1);
+
+            return done();
+        });
+
+        db.run("INSERT INTO update_hooks_test VALUES (1, 'value')", function(err) {
+            if (err) return done(err);
+        });
+    });
+
+    it('emits update event on row modification in table', function(done) {
+        db.run("INSERT INTO update_hooks_test VALUES (2, 'value'), (3, 'value4')", function(err) {
+            if (err) return done(err);
+
+            db.addListener('change', function(eventType, database, table, rowId) {
+                assert.equal(eventType, 'update');
+                assert.equal(database, 'main');
+                assert.equal(table, 'update_hooks_test');
+                assert.equal(rowId, 1);
+
+                db.all("SELECT * FROM update_hooks_test WHERE rowid = ?", rowId, function(err, rows) {
+                    assert.deepEqual(rows, [{ id: 2, value: 'new_val' }]);
+
+                    return done(err);
+                });
+            });
+
+            db.run("UPDATE update_hooks_test SET value = 'new_val' WHERE id = 2", function(err) {
+                if (err) return done(err);
+            });
+        });
+    });
+
+    it('emits delete event on row was deleted from table', function(done) {
+        db.run("INSERT INTO update_hooks_test VALUES (2, 'value')", function(err) {
+            if (err) return done(err);
+
+            db.addListener('change', function(eventType, database, table, rowId) {
+                assert.equal(eventType, 'delete');
+                assert.equal(database, 'main');
+                assert.equal(table, 'update_hooks_test');
+                assert.equal(rowId, 1);
+
+                return done();
+            });
+
+            db.run("DELETE FROM update_hooks_test WHERE id = 2", function(err) {
+                if (err) return done(err);
+            });
+        });
+    });
+
+    afterEach(function(done) {
+        db.close(done);
+    });
+});