Solr search query by Datetime.Year

Question

I configured Solr index to the path where I created some articles using templates, templates have the same fields with data type as in below model

<Root>/sitecore/content/Articles</Root>

My model looks like this

public class Article : SearchResultItem
{
    [IndexField("_uniqueid")]
    public string ItemPath { get; set; }

    [IndexField("_group")]
    public string Id { get; set; }

    [IndexField("title")]
    public string Title { get; set; }

    [IndexField("publisheddate")]
    public DateTime PublishedDate { get; set; }

    [IndexField("summary")]
    public string Summary { get; set; }

}

When I query I can get the list of articles and I can read correct PublishedDate, but when I extend my query where I want articles in a year

list.Where(c => c.PublishedDate.Year == 2017).ToList();

It returns zero rows

Answer 1

As mentioned by @jrap in the comments, you can use computed fields to solve this.

To use computed field, you would need to

1) Create a class that contains the logic to generate/calculate your new computed field

public class ComputedYearField: IComputedIndexField

{
 public string FieldName { get; set; }
 public string ReturnType { get; set; }

 public object ComputeFieldValue(IIndexable indexable) {

  Item item = (indexable as SitecoreIndexableItem);

  if (item != null)
  {

   // check if item is an Article
   if(item.TemplateID == "YOURARTICLETEMPLATEID")
   {
    // extract the year from PublishDate field 
    var dateField = (DateField)item.Fields["PublishedDate"];
    var itemDate = Sitecore.DateUtil.IsoDateToDateTime(dateField.Value);

    return itemDate.Year
   }
  }
  return null;
 }

}

2) Patch your Sitecore Solr(or lucene) settings so that the computed field will be run during indexing.

<fields hint="raw:AddComputedIndexField">
<field fieldName="ComputedYear" returnType="int">
     MyProjectNamespace.ComputedYearField,MyProjectNamespace
</field>
</fields>

3) Run reindex of your Sitecore indexes. Then you would be able to use your computed field

list.Where(c => c.ComputedYear == 2017).ToList();

You can find more details on computed fields in this blogpost

PS: I have not tested the code above

Answer 2

If you want to query against Date field you should compare with Datetime type.

date.Year, date.Month etc. don`t work with date field queries.

Rewrite your query like this:

var dateStart = new DateTime(year, 1, 1);
var dateEnd = new DateTime(year, 12, DateTime.DaysInMonth(year,12));

list.Where(x => x.Date.Between(dateStart, dateEnd, Inclusion.Both));
// or
// list.Where(x => x.Date>=dateStart && x.Date<=dateEnd);