dynamic fields sorting in elasticsearch and.net

Question

I am trying to sort records based on dynamic field names sent to the search API. the d19FilterCriteria object gives me the field name(SortOn) and the order(SortOrder) for sorting. I have used a sort descriptor for this purpose.

   var sortDescriptor = new SortDescriptor<MPANStatus>();
   // If Field Name is Dynamic
 if (d19FilterCriteria.SortOrder == "asc")
  {
    sortDescriptor.Field(d19FilterCriteria.SortOn, Nest.SortOrder.Ascending);
  }
else if (d19FilterCriteria.SortOrder == "desc")
  {
    sortDescriptor.Field(d19FilterCriteria.SortOn, Nest.SortOrder.Descending);
  }

 var result = await _elasticClient.SearchAsync<MPANStatus>(s => s
                 .Index("ampower-mpanstatusindex")
                 .Skip(skip)
                 .Size(pageSize)
                 .Sort(sort => 
                 {
                     sort = sortDescriptor;
                     return sort;
                 })

While debugging the sort descriptor shows me an object that has a valid value for Name and order

This query returns empty list for this code. Could I know what the issue here is?

Could you share index mapping and result.DebugInformation? — Rob
– Rob, Commented Nov 21, 2019 at 7:49

Nikunj Banker · Accepted Answer · 2019-11-21 10:50:25Z

0

You can have list of sort order based on your inputs:

List<ISort> sdBookSortOrder = new List<ISort>();
SortOrder oSortOrder = SortOrder.Ascending;  //SortOrder.Descending;
sdBookSortOrder.Add(new FieldSort { Field = <sField1>, Order = oSortOrder });
sdBookSortOrder.Add(new FieldSort { Field = <sField2>, Order = oSortOrder });

And, you can use above sort order collection while sending search request - as shown below:

ISearchRequest searchRequest = new SearchRequest(SearchEngine.IndexName)
  {
    From = iFrom,
    Size = iSize,
    Query = query,
    Sort = oSortOrder,
  };

I hope, it will solve your problem.

Regards, Nikunj

answered Nov 21, 2019 at 10:50

Nikunj Banker

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Comments

Balaji Arun · Accepted Answer · 2022-06-24 10:02:41Z

0

My guess is since you are using the dynamic mapping, the string will be considered as text field and sub field keyword use field.keyword instead of just field

answered Jun 24, 2022 at 10:02

Balaji Arun

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Rodolpho Lopes · Accepted Answer · 2022-08-30 11:43:03Z

The better approach to work with dynamic sorting fields using NEST, it's using SortDescriptor

SortDescriptor<dynamic> sort = GetSorting(request.Sorting);
ISearchResponse result = elasticClient.Search<YourType>(s => s
            .Index("your-index")
            .Sort(s => sort));

Use this method to add a list of sorting

// method to generate the Sorting
public SortDescriptor<dynamic> GetSorting(List<Sort>? sorting) 
{
  SortDescriptor<dynamic> sortDescriptor = new();

  if (sorting != null)
  {
    foreach (Sort sort in sorting)
      sortDescriptor.Field(sort.Field, getOrder(sort.Order));
  }

  return sortDescriptor;
 }

class "Sort" just to store Field and Order values

public string Field { get; set; }
public string Order { get; set; }

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