add find one

Author: shuangela

source/crud/query/find.txt

@@ -53,6 +53,36 @@ collection.
 
 To learn more about query filters, see the :ref:`kotlin-sync-specify-query` guide.
 
+Find One Document Example
+~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The following example chains the ``first()`` method to the ``find()`` method call to find
+the first document in which the value of the ``cuisine`` field is ``"Spanish"``:
+
+.. literalinclude:: /includes/read/retrieve.kt
+   :start-after: start-find-one
+   :end-before: end-find-one
+   :language: kotlin
+   :copyable:
+   :dedent:
+
+The ``find()`` operation in the preceding example returns a MongoDB document
+which you can print, as shown in the following example:
+
+.. io-code-block::
+   :copyable: true
+
+   .. input:: /includes/read/retrieve.kt
+      :start-after: start-find-iterate
+      :end-before: end-find-iterate
+      :language: kotlin
+      :dedent:
+   
+   .. output::
+      :visible: false
+
+      Restaurant(name=Tropicoso Club, cuisine=Spanish)
+
 Find Documents Example
 ~~~~~~~~~~~~~~~~~~~~~~
 

source/includes/read/retrieve.kt

@@ -26,13 +26,22 @@ fun main() {
     val results = collection.find(eq(Restaurant::cuisine.name, "Spanish"))
     // end-find
 
+    // start-find-one
+    val results = collection.find(eq(Restaurant::cuisine.name, "Spanish")).firstOrNull()
+    // end-find-one
+
     // start-find-iterate
     val results = collection.find(eq(Restaurant::cuisine.name, "Spanish"))
     results.forEach { result ->
         println(result)
     }
     // end-find-iterate
 
+    // start-find-one-print
+    val results = collection.find(eq(Restaurant::cuisine.name, "Spanish"))
+    println(results)
+    // end-find-one-print
+
     // start-find-all
     val results = collection.find()
     // end-find-all