How can I materialize a string to the actual type?-CodePudding

I am creating a projection variable like this:

var projection = Builders<Items>.Projection
                            .Include(x => x.Name);

The Include method takes an expression Expression<Func<TSource,object>> field.

What I would like to do is to convert a string parameter named key for example to x.Name, to be able to dynamically project other fields of Items at runtime.

var key = "Name";
var projection = Builders<Items>.Projection
                         .Include(x => x."key");

CodePudding user response：

As written this answer from the comment as the future reference, you can apply

.Include(key)

Provide a string value which is the field name.

As from ProjectDefinition<TDocument>.Include<TDocument>(), it supports with the parameter of FieldDefinition type,

public static ProjectionDefinition<TDocument> Include<TDocument>(this ProjectionDefinition<TDocument> projection, FieldDefinition<TDocument> field)

which FieldDefinition<TDocument> would perform an implicit cast from the string value.

public static implicit operator FieldDefinition<TDocument>(string fieldName)