diff --git a/src/db.ts b/src/db.ts
index cfebbbe..5f4face 100644
--- a/src/db.ts
+++ b/src/db.ts
@@ -137,31 +137,34 @@ export default class db {
   // changelog entry, expects (req, this (from query helper)) or (req, collection, conditions, data)
   static log(req, thisOrCollection, conditions = null, data = null) {
     if (! (conditions || data)) {  // (req, this)
+      console.log(11);
       data = thisOrCollection._update ? _.cloneDeep(thisOrCollection._update) : {};  // replace undefined with {}
+      // replace keys with a leading $
       Object.keys(data).forEach(key => {
         if (key[0] === '$') {
           data[key.substr(1)] = data[key];
           delete data[key];
         }
       });
-      new ChangelogModel({
+      console.log(thisOrCollection._conditions);
+      new ChangelogModel(this.logEscape(_.cloneDeep({
         action: req.method + ' ' + req.url,
         collection_name: thisOrCollection._collection.collectionName,
         conditions: thisOrCollection._conditions,
         data: data,
         user_id: req.authDetails.id ? req.authDetails.id : null
-      }).save(err => {
+      }))).save({validateBeforeSave: false}, err => {
         if (err) console.error(err);
       });
     }
     else {  // (req, collection, conditions, data)
-      new ChangelogModel({
+      new ChangelogModel(this.logEscape(_.cloneDeep({
         action: req.method + ' ' + req.url,
         collection_name: thisOrCollection,
         conditions: conditions,
         data: data,
         user_id: req.authDetails.id ? req.authDetails.id : null
-      }).save(err => {
+      }))).save(err => {
         if (err) console.error(err);
       });
     }
@@ -178,4 +181,17 @@ export default class db {
     });
     return object;
   }
+
+  private static logEscape(obj) {  // replace MongoDB control characters in keys
+    if (Object(obj) === obj && Object.keys(obj).length > 0) {
+      Object.keys(obj).forEach(key => {
+        const safeKey = key.replace(/[$.]/g, '');
+        obj[safeKey] = this.logEscape(obj[key]);
+        if (key !== safeKey) {
+          delete obj[key];
+        }
+      });
+    }
+    return obj;
+  }
 };
diff --git a/src/models/changelog.ts b/src/models/changelog.ts
index b26bd16..57701a9 100644
--- a/src/models/changelog.ts
+++ b/src/models/changelog.ts
@@ -3,9 +3,9 @@ import mongoose from 'mongoose';
 const ChangelogSchema = new mongoose.Schema({
   action: String,
   collection_name: String,
-  conditions: Object,
+  conditions: mongoose.Schema.Types.Mixed,
   data: Object,
   user_id: mongoose.Schema.Types.ObjectId
-}, {minimize: false});
+}, {minimize: false, strict: false});
 
 export default mongoose.model<any, mongoose.Model<any, any>>('changelog', ChangelogSchema);
\ No newline at end of file
diff --git a/src/routes/model.spec.ts b/src/routes/model.spec.ts
index 5be66b7..88a963e 100644
--- a/src/routes/model.spec.ts
+++ b/src/routes/model.spec.ts
@@ -2,6 +2,8 @@ import should from 'should/as-function';
 import ModelFileModel from '../models/model_file';
 import TestHelper from "../test/helper";
 import ModelModel from '../models/model';
+import UserModel from '../models/user';
+import mongoose from 'mongoose';
 
 
 describe('/model', () => {
@@ -232,6 +234,22 @@ describe('/model', () => {
         });
       });
     });
+    it ('removes the model_id from all user.models', done => {
+      TestHelper.request(server, done, {
+        method: 'delete',
+        url: '/model/VN/Model%20A',
+        auth: {basic: 'admin'},
+        httpStatus: 200
+      }).end((err, res) => {
+        if (err) return done(err);
+        should(res.body).be.eql({status: 'OK'});
+        UserModel.find({models: mongoose.Types.ObjectId("120000000000000000000001")}).lean().exec((err, res) => {
+          if (err) return done(err);
+          should(res).have.lengthOf(0);
+          done();
+        });
+      });
+    });
     it('returns 404 for an unknown group', done => {
       TestHelper.request(server, done, {
         method: 'delete',
diff --git a/src/routes/model.ts b/src/routes/model.ts
index c771ff9..70bf5ac 100644
--- a/src/routes/model.ts
+++ b/src/routes/model.ts
@@ -3,6 +3,7 @@ import bodyParser from 'body-parser';
 
 import ModelFileModel from '../models/model_file';
 import ModelModel from '../models/model';
+import UserModel from '../models/user';
 import _ from 'lodash';
 import ModelValidate from './validate/model';
 import res400 from './validate/res400';
@@ -54,7 +55,7 @@ router.post('/model/:group', (req, res, next) => {
           {$push: {models: model as never}}
         ).log(req).lean().exec(err => {
           if (err) return next(err);
-          res.json({status: 'OK'})
+          res.json({status: 'OK'});
         });
       }
     }
@@ -62,7 +63,7 @@ router.post('/model/:group', (req, res, next) => {
       new ModelModel({group: req.params.group, models: [model]}).save((err, data) => {
         if (err) return next(err);
         db.log(req, 'models', {_id: data._id}, data.toObject());
-        res.json({status: 'OK'})
+        res.json({status: 'OK'});
       });
     }
   });
@@ -77,21 +78,26 @@ router.delete('/model/:group(((?!file)[^\\/]+?))/:name', (req, res, next) => {
     if (!data || !data.models.find(e => e.name === req.params.name)) {
       return res.status(404).json({status: 'Not found'});
     }
-    if (data.models.length > 1) {  // only remove model
-      ModelModel.findOneAndUpdate(
-        {group: req.params.group},
-        {$pull: {models: data.models.find(e => e.name === req.params.name) as never}}
-      ).log(req).lean().exec(err => {
-        if (err) return next(err);
-        res.json({status: 'OK'})
-      });
-    }
-    else {  // remove document
-      ModelModel.findOneAndDelete({group: req.params.group}).log(req).lean().exec(err => {
-        if (err) return next(err);
-        res.json({status: 'OK'})
-      });
-    }
+    // delete all references in user.models
+    UserModel.updateMany({}, {$pull: {models: data.models.find(e => e.name === req.params.name)._id as never}},
+      { multi: true }).log(req).lean().exec(err => {
+      if (err) return next(err);
+      if (data.models.length > 1) {  // only remove model
+        ModelModel.findOneAndUpdate(
+          {group: req.params.group},
+          {$pull: {models: data.models.find(e => e.name === req.params.name) as never}}
+        ).log(req).lean().exec(err => {
+          if (err) return next(err);
+          res.json({status: 'OK'})
+        });
+      }
+      else {  // remove document
+        ModelModel.findOneAndDelete({group: req.params.group}).log(req).lean().exec(err => {
+          if (err) return next(err);
+          res.json({status: 'OK'})
+        });
+      }
+    });
   });
 });