copy_to elasticsearch 6 analizers - elasticsearch

Question

I am using elasticsearch 6 nest for dot.net
I used _all field in order to search all the index but now since its deprecated i need a new solution
I have found the copy_to option which is good enough.
My question is : i used to define to the _all field which analyzer it should use (ngram) and which search analyzer it should use (whitespace) for my project reasons.
Now since the copy_to field is not declared in the mappings i am unable to define it, any idea would be appreciated.
var res = client1.CreateIndex(INDEX_NAME, desc => desc
.InitializeUsing(indexState)
.Settings(x => x
.Analysis(g => g
.Tokenizers(t => t
.NGram("ngram_tokenizer", y => y
.MinGram(3)
.MaxGram(7)
.TokenChars(
TokenChar.Letter,
TokenChar.Digit,
TokenChar.Punctuation,
TokenChar.Symbol
)))
.Analyzers(o => o
.Custom("ngram_analyzer", w => w.Tokenizer("ngram_tokenizer").Filters("lowercase"))
.Whitespace("whitespace_analyzer")
.Standard("standard_analyzer", e => e.MaxTokenLength(1111)))))
.Mappings(ms => ms
.Map<SampleClass>(m => m
.AutoMap() //Still auto map exists if there are attributes on the class definition
.Properties(ps => ps //Override auto map
.Text(s => s
.Name(n => n.SampleString)
.CopyTo(am=>am.Field("searchallfield")))
.Number(s => s
.Name(n => n.SampleInteger))
.Date(s => s
.Name(n => n.SampleDateTime)
.Format("MM-DD-YY"))
))));

Answer 1

Apparently you can define the copy_to field in the mappings
.Map<SampleClass>(m => m
.AutoMap() //Still auto map exists if there are attributes on the class definition
.Properties(ps => ps //Override auto map
.Text(yy=>yy
.Name("searchallfield")
.SearchAnalyzer("whitespace_analyzer")
.Analyzer("ngram_analyzer"))
.Text(s => s
.Name(n => n.SampleString)
.CopyTo(am=>am.Field("searchallfield")))
.Number(s => s
.Name(n => n.SampleInteger))
.Date(s => s
.Name(n => n.SampleDateTime))