# putItem

### Spec

```typescript
async putItem<TSource>(
    tnmInput: TynamoPutItemInput<TSource>
): Promise<TynamoPutItemOutput<TSource>>;
```

### Input&#x20;

```typescript
export interface TynamoPutItemInput<TSource> {
    Item: TSource;
    ExpressionAttributeValues?: any;
    
    // Dervied from DynamoDB
    ReturnValues?: ReturnValue;
    ReturnConsumedCapacity?: ReturnConsumedCapacity;
    ReturnItemCollectionMetrics?: ReturnItemCollectionMetrics;
    ExpressionAttributeNames?: ExpressionAttributeNameMap;
    ConditionExpression?: ConditionExpression;
}
```

| Name                      | Type            | Info                           |
| ------------------------- | --------------- | ------------------------------ |
| Item                      | `@DynamoEntity` | Item to insert into the table. |
| ExpressionAttributeValues | `@DynamoEntity` | Value used for expression.     |

{% hint style="info" %}
Unlisted param is derived from `DynamoDB`.

Check [here](https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/DynamoDB.html) for more information.
{% endhint %}

### Output

```typescript
export interface TynamoPutItemOutput<TSource> {
    Attributes?: TSource;
    
    // Derived from DynamoDB.
    $response: AWS.Response<PutItemOutput, AWS.AWSError>;
    ConsumedCapacity?: ConsumedCapacity;
    ItemCollectionMetrics?: ItemCollectionMetrics;
}
```

| Name       | Type            | Info                                                                                                                                     |
| ---------- | --------------- | ---------------------------------------------------------------------------------------------------------------------------------------- |
| Attributes | `@DynamoEntity` | The attribute values as they appeared before the `PutItem` operation, but only if ReturnValues is specified as `ALL_OLD` in the request. |

{% hint style="info" %}
Unlisted param is derived from `DynamoDB`.

Check [here](https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/DynamoDB.html) for more information.
{% endhint %}

### Example

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

    @DynamoProperty({ keyType: KeyType.attr })
    name!: string;

    constructor(id: number, name: string, favoriteNumbers: number[]) {
        this.id = id;
        this.name = name;
    }
}

const tynamo: Tynamo = new Tynamo({
    region: "ap-northeast-2",
    endpoint: "http://localhost:8000"
});
const tynamoTable = tynamo.getTableOf(Cat);


// Insert if, garfield is not exist.
await tynamoTable.putItem({
    Item: new Cat(666, "garfield"),
    ConditionExpression: "attribute_not_exists(#id)"
});
```


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