diff --git a/examples/getstarted/api/restaurant/models/Restaurant.settings.json b/examples/getstarted/api/restaurant/models/Restaurant.settings.json
index 2ab966e87f..26ba49bf47 100755
--- a/examples/getstarted/api/restaurant/models/Restaurant.settings.json
+++ b/examples/getstarted/api/restaurant/models/Restaurant.settings.json
@@ -8,10 +8,7 @@
   "options": {
     "draftAndPublish": true,
     "increments": true,
-    "timestamps": [
-      "created_at",
-      "updated_at"
-    ],
+    "timestamps": ["created_at", "updated_at"],
     "comment": ""
   },
   "pluginOptions": {
@@ -41,13 +38,7 @@
       }
     },
     "price_range": {
-      "enum": [
-        "very_cheap",
-        "cheap",
-        "average",
-        "expensive",
-        "very_expensive"
-      ],
+      "enum": ["very_cheap", "cheap", "average", "expensive", "very_expensive"],
       "type": "enumeration",
       "pluginOptions": {
         "i18n": {
@@ -169,15 +160,6 @@
           "localized": true
         }
       }
-    },
-    "parent": {
-      "collection": "restaurant",
-      "via": "children",
-      "dominant": true
-    },
-    "children": {
-      "collection": "restaurant",
-      "via": "parent"
     }
   }
 }
diff --git a/packages/strapi-plugin-i18n/config/functions/bootstrap.js b/packages/strapi-plugin-i18n/config/functions/bootstrap.js
index 0b8d62c51e..9d68611849 100644
--- a/packages/strapi-plugin-i18n/config/functions/bootstrap.js
+++ b/packages/strapi-plugin-i18n/config/functions/bootstrap.js
@@ -16,7 +16,8 @@ module.exports = async () => {
   const { actionProvider } = strapi.admin.services.permission;
   actionProvider.register(actions);
 
-  getService('entity-service-decorator').decorate();
+  const { decorator } = getService('entity-service-decorator');
+  strapi.entityService.decorate(decorator);
 
   await getService('locales').initDefaultLocale();
 
diff --git a/packages/strapi-plugin-i18n/services/__tests__/entity-service-decorator.test.js b/packages/strapi-plugin-i18n/services/__tests__/entity-service-decorator.test.js
new file mode 100644
index 0000000000..5541b869e4
--- /dev/null
+++ b/packages/strapi-plugin-i18n/services/__tests__/entity-service-decorator.test.js
@@ -0,0 +1,240 @@
+'use strict';
+
+jest.mock('../localizations', () => {
+  return {
+    syncLocalizations: jest.fn(async () => {}),
+    updateNonLocalizedFields: jest.fn(async () => {}),
+  };
+});
+
+const { decorator } = require('../entity-service-decorator');
+const { syncLocalizations, updateNonLocalizedFields } = require('../localizations');
+
+const model = {
+  pluginOptions: {
+    i18n: {
+      localized: true,
+    },
+  },
+};
+
+const nonLocalizedModel = {
+  pluginOptions: {
+    i18n: {
+      localized: false,
+    },
+  },
+};
+
+const models = {
+  'test-model': model,
+  'non-localized-model': nonLocalizedModel,
+};
+
+describe('Entity service decorator', () => {
+  beforeAll(() => {
+    global.strapi = {
+      query() {
+        return {
+          create() {},
+          update() {},
+        };
+      },
+      db: {
+        getModel(uid) {
+          return models[uid || 'test-model'];
+        },
+      },
+      store: () => ({ get: () => 'en' }),
+    };
+  });
+
+  beforeEach(() => {
+    syncLocalizations.mockClear();
+    updateNonLocalizedFields.mockClear();
+  });
+
+  describe('wrapOptions', () => {
+    test('Calls original wrapOptions', async () => {
+      const defaultService = {
+        wrapOptions: jest.fn(() => Promise.resolve('li')),
+      };
+
+      const service = decorator(defaultService);
+
+      const input = { populate: ['test'] };
+      await service.wrapOptions(input, { model: 'test-model' });
+
+      expect(defaultService.wrapOptions).toHaveBeenCalledWith(input, { model: 'test-model' });
+    });
+
+    test('Does not wrap options if model is not localized', async () => {
+      const defaultService = {
+        wrapOptions: jest.fn(opts => Promise.resolve(opts)),
+      };
+      const service = decorator(defaultService);
+
+      const input = { populate: ['test'] };
+      const output = await service.wrapOptions(input, { model: 'non-localized-model' });
+
+      expect(output).toStrictEqual(input);
+    });
+
+    test('does not change non params options', async () => {
+      const defaultService = {
+        wrapOptions: jest.fn(opts => Promise.resolve(opts)),
+      };
+      const service = decorator(defaultService);
+
+      const input = { populate: ['test'] };
+      const output = await service.wrapOptions(input, { model: 'test-model' });
+
+      expect(output.populate).toStrictEqual(input.populate);
+    });
+
+    test('Adds locale param', async () => {
+      const defaultService = {
+        wrapOptions: jest.fn(opts => Promise.resolve(opts)),
+      };
+      const service = decorator(defaultService);
+
+      const input = { populate: ['test'] };
+      const output = await service.wrapOptions(input, { model: 'test-model' });
+
+      expect(output).toMatchObject({ params: { locale: 'en' } });
+    });
+
+    test('Replaces _locale param', async () => {
+      const defaultService = {
+        wrapOptions: jest.fn(opts => Promise.resolve(opts)),
+      };
+      const service = decorator(defaultService);
+
+      const input = {
+        params: {
+          _locale: 'fr',
+        },
+        populate: ['test'],
+      };
+      const output = await service.wrapOptions(input, { model: 'test-model' });
+
+      expect(output).toMatchObject({ params: { locale: 'fr' } });
+    });
+  });
+
+  describe('create', () => {
+    test('Calls original create', async () => {
+      const entry = {
+        id: 1,
+      };
+
+      const defaultService = {
+        create: jest.fn(() => Promise.resolve(entry)),
+      };
+
+      const service = decorator(defaultService);
+
+      const input = { data: { title: 'title ' } };
+      await service.create(input, { model: 'test-model' });
+
+      expect(defaultService.create).toHaveBeenCalledWith(input, { model: 'test-model' });
+    });
+
+    test('Calls syncLocalizations if model is localized', async () => {
+      const entry = {
+        id: 1,
+        localizations: [{ id: 2 }],
+      };
+
+      const defaultService = {
+        create: jest.fn(() => Promise.resolve(entry)),
+      };
+
+      const service = decorator(defaultService);
+
+      const input = { data: { title: 'title ' } };
+      await service.create(input, { model: 'test-model' });
+
+      expect(defaultService.create).toHaveBeenCalledWith(input, { model: 'test-model' });
+      expect(syncLocalizations).toHaveBeenCalledWith(entry, { model });
+    });
+
+    test('Skip processing if model is not localized', async () => {
+      const entry = {
+        id: 1,
+        localizations: [{ id: 2 }],
+      };
+
+      const defaultService = {
+        create: jest.fn(() => Promise.resolve(entry)),
+      };
+
+      const service = decorator(defaultService);
+
+      const input = { data: { title: 'title ' } };
+      const output = await service.create(input, { model: 'non-localized-model' });
+
+      expect(defaultService.create).toHaveBeenCalledWith(input, { model: 'non-localized-model' });
+      expect(syncLocalizations).not.toHaveBeenCalled();
+      expect(output).toStrictEqual(entry);
+    });
+  });
+
+  describe('update', () => {
+    test('Calls original update', async () => {
+      const entry = {
+        id: 1,
+      };
+
+      const defaultService = {
+        update: jest.fn(() => Promise.resolve(entry)),
+      };
+
+      const service = decorator(defaultService);
+
+      const input = { params: { id: 1 }, data: { title: 'title ' } };
+      await service.update(input, { model: 'test-model' });
+
+      expect(defaultService.update).toHaveBeenCalledWith(input, { model: 'test-model' });
+    });
+
+    test('Calls updateNonLocalizedFields if model is localized', async () => {
+      const entry = {
+        id: 1,
+        localizations: [{ id: 2 }],
+      };
+
+      const defaultService = {
+        update: jest.fn(() => Promise.resolve(entry)),
+      };
+
+      const service = decorator(defaultService);
+
+      const input = { params: { id: 1 }, data: { title: 'title ' } };
+      const output = await service.update(input, { model: 'test-model' });
+
+      expect(defaultService.update).toHaveBeenCalledWith(input, { model: 'test-model' });
+      expect(updateNonLocalizedFields).toHaveBeenCalledWith(entry, { model });
+      expect(output).toStrictEqual(entry);
+    });
+
+    test('Skip processing if model is not localized', async () => {
+      const entry = {
+        id: 1,
+        localizations: [{ id: 2 }],
+      };
+
+      const defaultService = {
+        update: jest.fn(() => Promise.resolve(entry)),
+      };
+
+      const service = decorator(defaultService);
+
+      const input = { params: { id: 1 }, data: { title: 'title ' } };
+      await service.update(input, { model: 'non-localized-model' });
+
+      expect(defaultService.update).toHaveBeenCalledWith(input, { model: 'non-localized-model' });
+      expect(updateNonLocalizedFields).not.toHaveBeenCalled();
+    });
+  });
+});
diff --git a/packages/strapi-plugin-i18n/services/entity-service-decorator.js b/packages/strapi-plugin-i18n/services/entity-service-decorator.js
index 1adbeec229..806ee2a0e1 100644
--- a/packages/strapi-plugin-i18n/services/entity-service-decorator.js
+++ b/packages/strapi-plugin-i18n/services/entity-service-decorator.js
@@ -1,20 +1,68 @@
 'use strict';
 
-const { getService } = require('../utils');
+const { has, omit } = require('lodash/fp');
 
-module.exports = {
-  decorate() {
-    strapi.entityService.decorate(entityServiceDecorator);
-  },
+const { getDefaultLocale } = require('./locales');
+const { isLocalized } = require('./content-types');
+const { syncLocalizations, updateNonLocalizedFields } = require('./localizations');
+
+const LOCALE_QUERY_FILTER = '_locale';
+
+/**
+ * Adds default locale or replaces _locale by locale in query params
+ * @param {object} params - query params
+ */
+const wrapParams = async (params = {}) => {
+  if (has(LOCALE_QUERY_FILTER, params)) {
+    return {
+      ...omit(LOCALE_QUERY_FILTER, params),
+      locale: params[LOCALE_QUERY_FILTER],
+    };
+  }
+
+  return {
+    ...params,
+    locale: await getDefaultLocale(),
+  };
 };
 
-const entityServiceDecorator = service => ({
-  async create(params, ctx) {
+/**
+ * Decorates the entity service with I18N business logic
+ * @param {object} service - entity service
+ */
+const decorator = service => ({
+  /**
+   * Wraps query options. In particular will add default locale to query params
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
+   */
+  async wrapOptions(opts = {}, ctx) {
+    const wrappedOptions = await service.wrapOptions(opts, ctx);
     const model = strapi.db.getModel(ctx.model);
-    const entry = await service.create(params, ctx);
 
-    if (getService('content-types').isLocalized(model)) {
-      await getService('localizations').syncLocalizations(entry, { model });
+    if (!isLocalized(model)) {
+      return wrappedOptions;
+    }
+
+    return {
+      ...wrappedOptions,
+      params: await wrapParams(wrappedOptions.params),
+    };
+  },
+
+  /**
+   * Creates an entry & make links between it and its related localizaionts
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
+   */
+  async create(opts, ctx) {
+    const model = strapi.db.getModel(ctx.model);
+    const entry = await service.create(opts, ctx);
+
+    if (isLocalized(model)) {
+      await syncLocalizations(entry, { model });
     }
 
     return entry;
@@ -22,17 +70,23 @@ const entityServiceDecorator = service => ({
 
   /**
    * Updates an entry & update related localizations fields
-   * @param {obj} params - query params
-   * @param {obj} ctx - query context (model)
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
    */
-  async update(params, ctx) {
+  async update(opts, ctx) {
     const model = strapi.db.getModel(ctx.model);
-    const entry = await service.update(params, ctx);
+    const entry = await service.update(opts, ctx);
 
-    if (getService('content-types').isLocalized(model)) {
-      await getService('localizations').updateNonLocalizedFields(entry, { model });
+    if (isLocalized(model)) {
+      await updateNonLocalizedFields(entry, { model });
     }
 
     return entry;
   },
 });
+
+module.exports = {
+  decorator,
+  wrapParams,
+};
diff --git a/packages/strapi/lib/services/entity-service.js b/packages/strapi/lib/services/entity-service.js
index 351c890578..294c7565d1 100644
--- a/packages/strapi/lib/services/entity-service.js
+++ b/packages/strapi/lib/services/entity-service.js
@@ -43,11 +43,25 @@ const createDefaultImplementation = ({ db, eventHub, entityValidator }) => ({
   uploadFiles,
 
   /**
-   * Promise to fetch all records
-   *
-   * @return {Promise}
+   * Returns default opt
+   * it is async so decorators can do async processing
+   * @param {object} params - query params to extend
+   * @param {object=} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
    */
-  async find({ params, populate }, { model }) {
+  async wrapOptions(options = {}) {
+    return options;
+  },
+
+  /**
+   * Returns a list of entries
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
+   */
+  async find(opts, { model }) {
+    const { params, populate } = await this.wrapOptions(opts, { model });
+
     const { kind } = db.getModel(model);
 
     // return first element and ignore filters
@@ -59,41 +73,63 @@ const createDefaultImplementation = ({ db, eventHub, entityValidator }) => ({
     return db.query(model).find(params, populate);
   },
 
-  findPage({ params, populate }, { model }) {
+  /**
+   * Returns a paginated list of entries
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
+   */
+  async findPage(opts, { model }) {
+    const { params, populate } = await this.wrapOptions(opts, { model });
+
     return db.query(model).findPage(params, populate);
   },
 
-  findWithRelationCounts({ params, populate }, { model }) {
+  /**
+   * Returns a list of entries with relation counters
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
+   */
+  async findWithRelationCounts(opts, { model }) {
+    const { params, populate } = await this.wrapOptions(opts, { model });
+
     return db.query(model).findWithRelationCounts(params, populate);
   },
 
   /**
-   * Promise to fetch record
-   *
-   * @return {Promise}
+   * Returns one entry
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
    */
+  async findOne(opts, { model }) {
+    const { params, populate } = await this.wrapOptions(opts, { model });
 
-  findOne({ params, populate }, { model }) {
     return db.query(model).findOne(params, populate);
   },
 
   /**
-   * Promise to count record
-   *
-   * @return {Promise}
+   * Returns a count of entries
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
    */
+  async count(opts, { model }) {
+    const { params } = await this.wrapOptions(opts, { model });
 
-  count({ params }, { model }) {
     return db.query(model).count(params);
   },
 
   /**
-   * Promise to add record
-   *
-   * @return {Promise}
+   * Creates & returns a new entry
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
    */
+  async create(opts, { model }) {
+    const { data, files } = await this.wrapOptions(opts, { model });
 
-  async create({ data, files }, { model }) {
     const modelDef = db.getModel(model);
 
     if (modelDef.kind === 'singleType') {
@@ -124,12 +160,14 @@ const createDefaultImplementation = ({ db, eventHub, entityValidator }) => ({
   },
 
   /**
-   * Promise to edit record
-   *
-   * @return {Promise}
+   * Updates & returns an existing entry
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
    */
+  async update(opts, { model }) {
+    const { params, data, files } = await this.wrapOptions(opts, { model });
 
-  async update({ params, data, files }, { model }) {
     const modelDef = db.getModel(model);
     const existingEntry = await db.query(model).findOne(params);
 
@@ -155,12 +193,14 @@ const createDefaultImplementation = ({ db, eventHub, entityValidator }) => ({
   },
 
   /**
-   * Promise to delete a record
-   *
-   * @return {Promise}
+   * Deletes & returns the entry that was deleted
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
    */
+  async delete(opts, { model }) {
+    const { params } = await this.wrapOptions(opts, { model });
 
-  async delete({ params }, { model }) {
     const entry = await db.query(model).delete(params);
 
     const modelDef = db.getModel(model);
@@ -173,29 +213,50 @@ const createDefaultImplementation = ({ db, eventHub, entityValidator }) => ({
   },
 
   /**
-   * Promise to search records
-   *
-   * @return {Promise}
+   * Returns a list of matching entries
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
    */
+  async search(opts, { model }) {
+    const { params, populate } = await this.wrapOptions(opts, { model });
 
-  search({ params, populate }, { model }) {
     return db.query(model).search(params, populate);
   },
 
-  searchWithRelationCounts({ params, populate }, { model }) {
+  /**
+   * Returns a list of matching entries with relations counters
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
+   */
+  async searchWithRelationCounts(opts, { model }) {
+    const { params, populate } = await this.wrapOptions(opts, { model });
+
     return db.query(model).searchWithRelationCounts(params, populate);
   },
 
-  searchPage({ params, populate }, { model }) {
+  /**
+   * Returns a paginated list of matching entries
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
+   */
+  async searchPage(opts, { model }) {
+    const { params, populate } = await this.wrapOptions(opts, { model });
+
     return db.query(model).searchPage(params, populate);
   },
 
   /**
    * Promise to count searched records
-   *
-   * @return {Promise}
+   * @param {object} opts - Query options object (params, data, files, populate)
+   * @param {object} ctx - Query context
+   * @param {object} ctx.model - Model that is being used
    */
-  countSearch({ params }, { model }) {
+  async countSearch(opts, { model }) {
+    const { params } = await this.wrapOptions(opts, { model });
+
     return db.query(model).countSearch(params);
   },
 });