How to do a simple map/reduce aggregation

[avin]

hi,

   I have a document collection named Books, which looks like this.

{
    "Name":"B",
    "Price":4
}
{
    "Name":"A",
    "Price":10
}

How do I perform a simple aggregation on the prices in the list? i.e., I just wana get the whole total prices of all documents in the collection Books. I don't want to perform any grouping, just a simple scalar result. How can I achieve this using map reduce? Any help will be highly appreciated.

Regards,

Avin

[Oren Eini (Ayende Rahien)]

group result by "constant" into g

[avin]

Ok Oren,  here is my code,

============================================================

public class GetTotalAssetStorageSize : AbstractIndexCreationTask<Asset,GetTotalAssetStorageSize.Result>

    {

        /// <summary>

        /// The class that maps the fields in Assets document for doing a full text search.

        /// </summary>

        public class Result

        {

            /// <summary>

            /// Gets or sets the FileSize.

            /// </summary>

            public int FileSize { get; set; }

        }

        /// <summary>

        /// Initializes a new instance of the GetTotalAssetStorageSize class.

        /// </summary>

        public GetTotalAssetStorageSize()

        {

            Map = assets => from asset in assets

                            select new

                            {

                                Total = asset.FileSize,

                            };

            Reduce = results => from result in results

                                group result by 1 into g

                                select new

                                {

                                    Total = g.Sum(x=>x.FileSize)

                                };

                     

        }

    }

============================================================

for fetching the results, I use the following code,

var results = this.Session.Query<GetTotalAssetStorageSize.Result,GetTotalAssetStorageSize>()   

                            .ToArray();

Do I miss something?  Please  help..............

Regards,

Avin

[Kijana Woodard]

Your result property is FileSize, but your reduce property is Total. Change Total to FileSize in your map and reduce.

[avin]

thx  Kijana, it worked.