diff --git a/.gitignore b/.gitignore
index c36cdd9..61c9e6e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -65,3 +65,5 @@ package-lock.json
 # Build output
 bundle/
 dist/
+
+.idea
diff --git a/lib/entity/entity-field.config.ts b/lib/entity/entity-field.config.ts
index a9f6fcf..1bdab2e 100644
--- a/lib/entity/entity-field.config.ts
+++ b/lib/entity/entity-field.config.ts
@@ -22,8 +22,10 @@ export interface FieldConfig{
 	 *
 	 * If an entity has the following property definition:
 	 *
+	 * ```typescript
 	 * @EntityField()
 	 * name:string;
+	 * ```
 	 *
 	 * Then when creating the model, if the raw data contains a `name` property with value 'Anna', the resulting model will have a `name` property with value 'Anna'.
 	 *
@@ -47,7 +49,7 @@ export interface FieldConfig{
 	 *
 	 * Then the model's `date` property will have a value of Date(1532422166428), since both creation_date and init_date have no value in the data.
 	 *
-	 * @example <caption>Using '__self' for data to pass the whole raw data</caption>
+	 * @example <caption>Using '\_\_self' for data to pass the whole raw data</caption>
 	 * In the case when we want to separate some properties of the raw data to a sub-model, it's possible to use the special value '__self' for the `data` field configuration.
 	 * This passes the whole raw data object to the field's creation, rather than just the value of a property. e.g:
 	 * ```typescript
@@ -61,6 +63,7 @@ export interface FieldConfig{
 	 * ```
 	 * In case we want to separate all address properties from a user into an encapsulated object, for the following raw data:
 	 *
+	 * ```json
 	 * {
 	 * 		"name": "Anna",
 	 * 		"street": "Prinsengracht 263-267",
@@ -68,6 +71,7 @@ export interface FieldConfig{
 	 * 		"city": "Amsterdam",
 	 * 		"country": "Holland"
 	 * }
+	 * ```
 	 */
 	data?:"__self" | string | Array<string>,
 
diff --git a/lib/services/paris.ts b/lib/services/paris.ts
index d5b1c4b..ecf09b5 100644
--- a/lib/services/paris.ts
+++ b/lib/services/paris.ts
@@ -27,6 +27,8 @@ import {catchError, map, mergeMap, switchMap, tap} from "rxjs/operators";
 import {DataTransformersService} from "./data-transformers.service";
 import {DataCache, DataCacheSettings} from "./cache";
 import * as _ from "lodash";
+import {EntityModelBase} from "../models/entity-model.base";
+import {EntityId} from "../models/entity-id.type";
 
 export class Paris{
 	private repositories:Map<DataEntityType, IRepository<ModelBase>> = new Map;
@@ -379,7 +381,7 @@ export class Paris{
 	 * @param {{[p: string]: any}} params
 	 * @returns {Observable<TEntity extends ModelBase>}
 	 */
-	getItemById<TEntity extends ModelBase>(entityConstructor:DataEntityConstructor<TEntity>, itemId: string | number, options?:DataOptions, params?:{ [index:string]:any }): Observable<TEntity>{
+	getItemById<TEntity extends EntityModelBase, TId extends EntityId = string>(entityConstructor:DataEntityConstructor<TEntity>, itemId: TId, options?:DataOptions, params?:{ [index:string]:any }): Observable<TEntity>{
 		options = options || defaultDataOptions;
 
 		let repository:Repository<TEntity> = this.getRepository(entityConstructor);