formation

Spec

formation<TSource>(
    source: TSource,
    RootTClass: ClassCapture<TSource>,
    formationType: FormationMask = FormationMask.Full
): AttributeMap

Convert DynamoEntity to AttributeMap.

Input

Name	Type	Information
source	TSource	Entity to convert to AttributeMap.
RootTClass	ClassCapture<TSource>	Reference of @DynamoEntity class
formationType	FormationMask	Conversion bitmask

An error is occurs, if the source is null or undefined.

Formation Mask

With Formation Mask, only certain information can be included in the DynamoItem. It is good for generate key.

FormationMask.ts

export enum FormationMask {
    HashKey = 0b001,
    RangeKey = 0b010,
    Body = 0b100,
    KeyOnly = 0b011, // == HashKey | RangeKey
    Full = 0b111     // == HashKey | RangeKey | Body
}

const dynamoItemKey: Item = Mapper.formation(badCat, Cat, FormationMask.KeyOnly);

Example

@DynamoEntity()
class Cat {
    @DynamoProperty({ keyType: KeyType.hash })
    id!: number;

    @DynamoProperty({ keyType: KeyType.attr })
    name!: string;
}
const badCat :Cat = {
    id: 666,
    name: "garfield"
};
const dynamo : AttributeMap = Mapper.formation(badCat, Cat);

It will be formationed as,

{
    "id": {
        "N": "666"
    },
    "name": {
        "S": "garfield"
    }
}

Internal Logic

Use the formatProperty method to perform a formation on all the properties, then merge all the results.