Invalid Method Call Argument in Content Search

Question

Sitecore version: 9.3

I am trying to fetch the media components with specific template and having a particular check-box selected using Sitecore query in my code.

I tried the following code snippet:

var selectedIndex = ContentSearchManager.GetIndex("sitecore_master_index");

using (var context = selectedIndex.CreateSearchContext())
{
  var results = context.GetQueryable<SearchResultItem>()
   .Where(x => (Convert.ToString(x.TemplateId).Equals(Constants.UnversionedImageTemplateId, StringComparison.InvariantCultureIgnoreCase) || Convert.ToString( x.TemplateId).Equals(Constants.Jpeg, StringComparison.InvariantCultureIgnoreCase))
    && (x.Fields[Constants.OptimizedCheckFieldName].ValueOrDefault() != 1)
    && x.Path.StartsWith(Constants.MediaLibraryPath)).GetResults();

  int count = results.Count();
}

But on execution, I am getting the following error:

System.NotSupportedException
  HResult=0x80131515
  Message=Invalid Method Call Argument Type: Field - FieldNode - Field: _template - Sitecore.Data.ID. Only constant arguments is supported.
  Source=Sitecore.ContentSearch.Linq
  StackTrace:
   at Sitecore.ContentSearch.Linq.Parsing.ExpressionParser.ValidateMethodCallArguments(IEnumerable`1 arguments)

I saw similar questions here but couldn't make sense of this issue. Appreciate if you can help me to understand as why this is happening.

Answer 1

Instead of executing

var results = context.GetQueryable<SearchResultItem>()
    .Where(x => (Convert.ToString(x.TemplateId).Equals(Constants.UnversionedImageTemplateId, StringComparison.InvariantCultureIgnoreCase) 
    || Convert.ToString( x.TemplateId).Equals(Constants.Jpeg, StringComparison.InvariantCultureIgnoreCase))

Use

// maybe Guid.ParseExact depending on the type of `TemplateId`
var unversionedImageTemplateId = ID.Parse(Constants.UnversionedImageTemplateId);
var jpegTemplateId = ID.Parse(Constants.Jpeg);

var results = context.GetQueryable<SearchResultItem>()
  .Where(x => x.TemplateId == unversionedImageTemplateId || x.TemplateId == jpegTemplateId)

Otherwise Sitecore tries to pass function down to (I think) Solr.Net and it cannot handle your logic inside the query correctly.