db.ts

function findAll(entityType: string, query: QueryObject): Promise<Array<any>> {
    const table: Dexie.Table<any, any> = db.table(entityType);

    // if there is filter query try to apply filters
    const maybeFiltered = applyFilteringObject(table, query.filter);
    const maybePaginated = applyPaginationObject(maybeFiltered, query.pagination)

    const promise = maybePaginated.toArray();
    return promise;
}

function applyPaginationObject(collection: Dexie.Collection<any, any>, pagination: PaginationObject): Dexie.Collection<any, any>{
    if (pagination){
        return collection.limit(pagination.limit).offset(pagination.limit)
    }

    return collection;
}

function applyFilteringObject(table: Dexie.Table<any, any>, filterObject: FilterObject): Dexie.Collection<any, any> {
    if (filterObject){
        if (_.isObject(filterObject.equals)) {
            return table.where(filterObject.equals)
        } else if (_.isObject(filterObject.isAnyOf)) {
            const anyOf = filterObject.isAnyOf;
            return table.where(anyOf.key).anyOf(anyOf.value);
        }
    }

    return table.toCollection();
}