A string that represents the name of an index field. Field names begin with a letter and can contain the following characters: a-z (lowercase), 0-9, and _ (underscore). The name "score" is reserved and cannot be used as a field name. To reference a document's ID, you can use the name _id.

Constraints:

Length

1 - 64

Pattern

[a-z][a-z0-9_]*

public string SourceField { get; set; }