fixes #135 JsonIdentityInfo support

Author: zigzago

kmongo-jackson-mapping/src/main/kotlin/org/litote/kmongo/jackson/KMongoBsonFactory.kt

@@ -46,13 +46,20 @@ internal class KMongoBsonFactory : BsonFactory() {
 
         override fun writeObjectId(objectId: Any) {
             if (objectId !is ObjectId) {
-                error("$objectId has to be ${ObjectId::class}")
+                //generation with @JsonIdentityInfo - see https://github.com/Litote/kmongo/issues/135
+                if (objectId is String) {
+                    writeFieldName("_id")
+                    writeString(objectId)
+                } else {
+                    error("$objectId has to be ${ObjectId::class}")
+                }
+            } else {
+                _writeArrayFieldNameIfNeeded()
+                _verifyValueWrite("write object id")
+                _buffer.putByte(_typeMarker, BsonConstants.TYPE_OBJECTID)
+                objectId.toByteArray().forEach { _buffer.putByte(it) }
+                flushBuffer()
             }
-            _writeArrayFieldNameIfNeeded()
-            _verifyValueWrite("write object id")
-            _buffer.putByte(_typeMarker, BsonConstants.TYPE_OBJECTID)
-            objectId.toByteArray().forEach { _buffer.putByte(it) }
-            flushBuffer()
         }
 
         fun writeBinary(binary: Binary) {

kmongo/src/test/kotlin/org/litote/kmongo/issues/Issue135JsonIdentityInfo.kt

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2017/2019 Litote
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.litote.kmongo.issues
+
+import com.fasterxml.jackson.annotation.JsonIdentityInfo
+import com.fasterxml.jackson.annotation.JsonIdentityReference
+import com.fasterxml.jackson.annotation.ObjectIdGenerators
+import org.junit.Test
+import org.litote.kmongo.AllCategoriesKMongoBaseTest
+import org.litote.kmongo.findOne
+import org.litote.kmongo.issues.Issue135JsonIdentityInfo.Entry
+import org.litote.kmongo.save
+import java.util.Collections
+import kotlin.test.assertEquals
+
+/**
+ *
+ */
+class Issue135JsonIdentityInfo : AllCategoriesKMongoBaseTest<Entry>() {
+
+    @JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator::class, property = "uri")
+    class Entry() {
+
+        constructor(uri: String) : this() {
+            this.uri = uri
+        }
+
+        lateinit var uri: String
+
+        @JsonIdentityReference(alwaysAsId = true)
+        var contains: MutableSet<Entry> = Collections.synchronizedSet(HashSet())
+
+    }
+
+    @JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator::class, property = "uri")
+    class OriginalEntry(val uri: String) {
+        @JsonIdentityReference(alwaysAsId = true)
+        var contains: MutableSet<OriginalEntry> = Collections.synchronizedSet(HashSet())
+    }
+
+    @Test
+    fun saveDoesNotFail() {
+        val entry = Entry("http://litote.org/kmongo")
+        col.save(entry)
+        assertEquals(entry.uri, col.findOne()?.uri)
+    }
+
+}