[REFACTOR] Update Readme and documentaion

README.md

@@ -140,23 +140,21 @@ Decorator accepts two arguments:
 -   Mappings - array of rules how to convert one field to another
 
     ```typescript
-    export class MappingRules {
-        source!: string; // Field name from the source object which would be mapped
-        target!: string; // Field name from the target object where to map
-        default?: any; // Default value if source field is null
-        expr?: (x: any) => any; // Expression for manual converting or preparing field
+    export class MappingRules<SourceField, TargetField, SourceFieldType, TargetFieldType> {
+        source!: SourceField; // String Field name from the source object which would be mapped
+        target!: TargetField; // String Field name from the target object where to map
+        default?: TargetFieldType; // Default value if source field is null
         isCollection?: Boolean = false; // Flag that enables Array.map converting for this field
-        converter?: Constructor<Converter<any, any>>; // Converter constructor for nested objects
+        expr?: (x: SourceFieldType) => TargetFieldType; // Expression for manual converting or preparing field
+        converter?: Constructor<Converter<SourceFieldType, TargetFieldType>>; // Converter constructor for nested objects
     }
     ```
 
-    Options in mapping rules have priority when evaluating:
+    Options in mapping rules have choice when evaluating:
 
-    1. Exec converting by `expr`
+    1. Exec converting by `expr` OR
     2. Exec converting by `converter.convert`
 
-    If one of this options empty, another will be successfully performed.
-
     Additionally:
 
     -   If source field is null then default value will be set and none `expr` or `converter` called

src/decorators.ts

@@ -8,18 +8,16 @@ import { type } from "os";
  * source - name of the source object field
  * source - name of the target object field
  * default - set default value if field is null
- * expr - helps to pre evaluate field value
  * isCollection - transform field value with Array.map
+ * expr - helps to  convert value instead implementing converter
  * converter - convert field value with converter
  *
  * Mapping has the next order:
  *  - Setup default in field if null
- *  - Evaluate expr
- *  - Evaluate converter
+ *  - Evaluate expr or Evaluate converter
  *
  *  If isCollection is true then for each value in collection will be performed:
- *  - Evaluate expr
- *  - Evaluate converter
+ *  - Evaluate expr or Evaluate converter
  */
 type Without<T, U> = { [P in Exclude<keyof T, keyof U>]?: never };
 type XOR<T, U> = (T | U) extends object ? (Without<T, U> & U) | (Without<U, T> & T) : T | U;

src/mapping.ts

@@ -36,6 +36,7 @@ function setProperty<T, K extends keyof T>(obj: T, key: K, value: T[K]) {
 
 /**
  * Generated mapping function
+ *
  * @param sourceObject - object that contains values
  * @param targetObject - object that will be filled according mapping
  * @param mappings - from => to mapping declaration with meta information
@@ -84,7 +85,7 @@ export function mapObject<
 
 /**
  * Describes order of converting.
- * Current realisation is: expr => converter.convert
+ *
  * @param expr - expression that will be evaluated
  * @param Converter - converter constructor
  */