From ec69b3f29b88482cc1b36d54f148094bf10311ea Mon Sep 17 00:00:00 2001
From: asmhatre <asmhatre@gmail.com>
Date: Tue, 4 Aug 2026 17:30:43 +0000
Subject: [PATCH] Part 3: @JsonProperty and @JsonIgnore, both directions

---
 .../part3annotations/D01RenameAndIgnore.java  | 44 +++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 src/main/java/com/ankurm/jackson3/part3annotations/D01RenameAndIgnore.java

diff --git a/src/main/java/com/ankurm/jackson3/part3annotations/D01RenameAndIgnore.java b/src/main/java/com/ankurm/jackson3/part3annotations/D01RenameAndIgnore.java
new file mode 100644
index 0000000..a65bc11
--- /dev/null
+++ b/src/main/java/com/ankurm/jackson3/part3annotations/D01RenameAndIgnore.java
@@ -0,0 +1,44 @@
+package com.ankurm.jackson3.part3annotations;
+
+import com.fasterxml.jackson.annotation.JsonIgnore;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import tools.jackson.databind.json.JsonMapper;
+
+/**
+ * Post: Jackson Annotations Cheat Sheet — https://ankurm.com/jackson-annotations-guide/
+ * Sections: "@JsonProperty" and "@JsonIgnore"
+ *
+ * Every @Json* annotation is imported from com.fasterxml.jackson.annotation, even
+ * on Jackson 3. jackson-annotations deliberately keeps the old group ID and package
+ * so one copy can be shared by Jackson 2 and Jackson 3 code on the same classpath.
+ */
+public class D01RenameAndIgnore {
+
+    public record OrderSummary(
+            @JsonProperty("order_id")      Long   orderId,
+            @JsonProperty("customer_name") String customerName) { }
+
+    public record UserAccount(
+            String username,
+            @JsonIgnore String passwordHash) { }
+
+    public static void main(String[] args) {
+        JsonMapper mapper = JsonMapper.builder().build();
+
+        System.out.println("rename    : "
+                + mapper.writeValueAsString(new OrderSummary(1001L, "Alice")));
+
+        // Deserialisation honours the renamed key in both directions.
+        OrderSummary back = mapper.readValue(
+                "{\"order_id\":1001,\"customer_name\":\"Alice\"}", OrderSummary.class);
+        System.out.println("read back : " + back);
+
+        System.out.println("ignore    : "
+                + mapper.writeValueAsString(new UserAccount("alice", "$2a$10$secret")));
+
+        // @JsonIgnore is bidirectional: the field is not read from JSON either.
+        UserAccount ignored = mapper.readValue(
+                "{\"username\":\"alice\",\"passwordHash\":\"injected\"}", UserAccount.class);
+        System.out.println("read back : passwordHash=" + ignored.passwordHash());
+    }
+}