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DataService

Description​

The methods of this service are primarily used to query data from the data table.

Before jumping into the example, you need to set up the CommandModule as described in the previous section.

Methods​

async getItem(key: DetailKey)​

The getItem method returns a set of attributes for the item with the given detail/primary key. If there is no matching item, getItem does not return any data and there will be no item element in the response.

Example:

const item = await this.dataService.getItem(detailDto);

if (!item) {
  throw new NotFoundException();
}
return new CatDataEntity(item as CatDataEntity);

async listItemsByPk( pk: string, opts?: ...)​

The listItemsByPk method returns one or more items.

There are two common usage:

  • List all item by primary key (pk)

Example:

const res = await this.dataService.listItemsByPk(pk);
return new CatListEntity(res as CatListEntity);
  • List items by primary key (pk) and use a filter expression on the sort key (sk).

For example, if you want to get an item by its primary key (pk), where the sort key (sk)starts with the value CAT# and limit 100 item.

const query = {
  sk: {
    skExpession: "begins_with(sk, :typeCode)",
    skAttributeValues: {
      ":typeCode": `CAT${KEY_SEPARATOR}`,
    },
  },
  limit: 100,
};
const res = await this.dataService.listItemsByPk(pk, query);
return new CatDataListEntity(res as CatDataListEntity);