Remember an index upon any reload

lib/persistence.js

@@ -104,7 +104,12 @@ Persistence.prototype.persistCachedDatabase = function (cb) {
   this.db.getAllData().forEach(function (doc) {
     toPersist += model.serialize(doc) + '\n';
   });
-  
+  Object.keys(this.db.indexes).forEach(function (fieldName) {
+    if (fieldName != "_id") {   // The special _id index is managed by datastore.js, the others need to be persisted
+      toPersist += model.serialize({ $$indexCreated: { fieldName: fieldName, unique: self.db.indexes[fieldName].unique, sparse: self.db.indexes[fieldName].sparse }}) + '\n';
+    }
+  });
+
   async.waterfall([
     async.apply(customUtils.ensureFileDoesntExist, self.tempFilename)
   , async.apply(customUtils.ensureFileDoesntExist, self.oldFilename)

test/db.test.js

@@ -2009,7 +2009,7 @@ describe('Database', function () {
     });   // ==== End of 'Removing indexes upon document update' ==== //
     
     
-    describe.skip('Persisting indexes', function () {
+    describe.only('Persisting indexes', function () {
     
       it('If the persistIndexes options is used, indexes are persisted to a separate file and recreated upon reload', function (done) {
         var persDb = "workspace/persistIndexes.db"
@@ -2043,8 +2043,19 @@ describe('Database', function () {
                 Object.keys(db.indexes)[1].should.equal("planet");                
                 db.indexes._id.getAll().length.should.equal(2);
                 db.indexes.planet.getAll().length.should.equal(2);
+
+                // After another reload the indexes are still there (i.e. they are preserved during autocompaction)
+                db = new Datastore({ filename: persDb });
+                db.loadDatabase(function (err) {
+                  assert.isNull(err);
+                  Object.keys(db.indexes).length.should.equal(2);
+                  Object.keys(db.indexes)[0].should.equal("_id");
+                  Object.keys(db.indexes)[1].should.equal("planet");                
+                  db.indexes._id.getAll().length.should.equal(2);
+                  db.indexes.planet.getAll().length.should.equal(2);
               
                 done();                
+                });
               });
             });
           });

test/persistence.test.js

@@ -126,6 +126,24 @@ describe('Persistence', function () {
     _.isEqual(treatedData[0], { _id: "1", a: 2, ages: [1, 5, 12] }).should.equal(true);
     _.isEqual(treatedData[1], { _id: "3", today: now }).should.equal(true);
   });
+  
+  it('If a doc contains $$indexCreated, no error is thrown during treatRawData and we can get the index options', function () {
+    var now = new Date()
+      , rawData = model.serialize({ _id: "1", a: 2, ages: [1, 5, 12] }) + '\n' +
+                  model.serialize({ $$indexCreated: { fieldName: "test", unique: true } }) + '\n' +
+                  model.serialize({ _id: "3", today: now })
+      , treatedData = Persistence.treatRawData(rawData).data
+      , indexes = Persistence.treatRawData(rawData).indexes
+      ;
+
+    Object.keys(indexes).length.should.equal(1);
+    assert.deepEqual(indexes.test, { fieldName: "test", unique: true });
+      
+    treatedData.sort(function (a, b) { return a._id - b._id; });
+    treatedData.length.should.equal(2);
+    _.isEqual(treatedData[0], { _id: "1", a: 2, ages: [1, 5, 12] }).should.equal(true);
+    _.isEqual(treatedData[1], { _id: "3", today: now }).should.equal(true);
+  });  
 
   it('Compact database on load', function (done) {
     d.insert({ a: 2 }, function () {