feat(paranoid): Add an option to have paranoid work like in v3

lib/model.js

@@ -69,7 +69,8 @@ class Model {
       }
     }
 
-    if (!model.options.timestamps || !model.options.paranoid || options.paranoid === false) {
+    const paranoid = options.paranoid !== undefined ? options.paranoid : model.options.paranoid;
+    if (!model.options.timestamps || !paranoid) {
       // This model is not paranoid, nothing to do here;
       return options;
     }
@@ -81,12 +82,20 @@ class Model {
 
     let deletedAtDefaultValue = deletedAtAttribute.hasOwnProperty('defaultValue') ? deletedAtAttribute.defaultValue : null;
 
-    deletedAtDefaultValue = deletedAtDefaultValue || {
-      [Op.or]: {
-        [Op.gt]: now,
-        [Op.eq]: null
+    if (!deletedAtDefaultValue) {
+      if (paranoid === 'simple') {
+        deletedAtDefaultValue = {
+          [Op.eq]: null
+        };
+      } else {
+        deletedAtDefaultValue = {
+          [Op.or]: {
+            [Op.gt]: now,
+            [Op.eq]: null
+          }
+        };
       }
-    };
+    }
 
     deletedAtObject[deletedAtAttribute.field || deletedAtCol] = deletedAtDefaultValue;
 
@@ -686,7 +695,7 @@ class Model {
    * @param {Object}                  [options.scopes] More scopes, defined in the same way as defaultScope above. See `Model.scope` for more information about how scopes are defined, and what you can do with them
    * @param {Boolean}                 [options.omitNull] Don't persist null values. This means that all columns with null values will not be saved
    * @param {Boolean}                 [options.timestamps=true] Adds createdAt and updatedAt timestamps to the model.
-   * @param {Boolean}                 [options.paranoid=false] Calling `destroy` will not delete the model, but instead set a `deletedAt` timestamp if this is true. Needs `timestamps=true` to work
+   * @param {Boolean|String}          [options.paranoid=false] Calling `destroy` will not delete the model, but instead set a `deletedAt` timestamp if this is true. Needs `timestamps=true` to work. If set to `'simple'`, paranoid queries will use `deletedAt is null` instead of also checking that `deletedAt` is in the future.
    * @param {Boolean}                 [options.underscored=false] Converts all camelCased columns to underscored if true. Will not affect timestamp fields named explicitly by model options and will not affect fields with explicitly set `field` option
    * @param {Boolean}                 [options.underscoredAll=false] Converts camelCased model names to underscored table names if true. Will not change model name if freezeTableName is set to true
    * @param {Boolean}                 [options.freezeTableName=false] If freezeTableName is true, sequelize will not try to alter the model name to get the table name. Otherwise, the model name will be pluralized

test/integration/model/find.test.js

@@ -1017,5 +1017,29 @@ describe(Support.getTestDialectTeaser('Model'), () => {
       });
     });
 
+    describe('with simple paranoid', () => {
+      it('should not find records where deletedAt set to future', function() {
+        const User = this.sequelize.define('paranoiduser', {
+          username: Sequelize.STRING
+        }, { paranoid: 'simple' });
+
+        return User.sync({ force: true }).then(() => {
+          return User.bulkCreate([
+            {username: 'Bob'},
+            {username: 'Tobi', deletedAt: moment().add(30, 'minutes').format()},
+            {username: 'Max', deletedAt: moment().add(30, 'days').format()},
+            {username: 'Tony', deletedAt: moment().subtract(30, 'days').format()}
+          ]);
+        }).then(() => {
+          return User.find({ where: {username: 'Tobi'} });
+        }).then(tobi => {
+          expect(tobi).to.be.null;
+        }).then(() => {
+          return User.findAll();
+        }).then(users => {
+          expect(users.length).to.be.eql(1);
+        });
+      });
+    });
   });
 });