fix(point): validate newlines on write_line_protocol

CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## 0.4.0 [unreleased]
 
+### Bug Fixes
+
+1. [#49](https://github.com/InfluxCommunity/influxdb3-rust/pull/49): Extra validation on `Point#write_line_protocol()` to error out if fields contains any newline (`\n`) character.
+
 ## 0.3.0 [2026-08-27]
 
 > ⚠️ This release requires Rust 1.91 or later.

src/point.rs

@@ -259,6 +259,37 @@ impl Point {
                 self.measurement
             )));
         }
+        // VALIDATION: '\n' characters are not supported
+        for (k, v) in self.tags() {
+            if k.contains('\n') || v.contains('\n') {
+                return Err(Error::Config(
+                    format!(
+                        "tag '{k}' contains a line break which is unsupported in line protocol; point '{}'",
+                        self.measurement
+                    )
+                ));
+            }
+        }
+        for (k, v) in self.fields() {
+            if k.contains('\n') {
+                return Err(Error::Config(
+                    format!(
+                        "field '{k}' contains a line break which is unsupported in line protocol; point '{}'",
+                        self.measurement
+                    )
+                ));
+            }
+            if let FieldValue::String(s) = v {
+                if s.contains('\n') {
+                    return Err(Error::Config(
+                        format!(
+                            "field '{k}' contains a line break which is unsupported in line protocol; point '{}'",
+                            self.measurement
+                        )
+                    ));
+                }
+            }
+        }
 
         // Measurement
         write_escaped_measurement(buf, &self.measurement);

tests/point_tests.rs

@@ -80,3 +80,40 @@ fn last_write_wins() {
     assert_eq!(lp.matches("v=").count(), 1);
     assert!(lp.contains("v=2i"));
 }
+
+#[test]
+#[should_panic = "contains a line break"]
+fn tag_names_should_reject_newlines() {
+    Point::new("m")
+        .tag("t\nag", "value")
+        .field("v", 1)
+        .to_line_protocol(Precision::Nanosecond)
+        .unwrap();
+}
+#[test]
+#[should_panic = "contains a line break"]
+fn tag_values_should_reject_newlines() {
+    Point::new("m")
+        .tag("tag", "val\nue")
+        .field("v", 1)
+        .to_line_protocol(Precision::Nanosecond)
+        .unwrap();
+}
+#[test]
+#[should_panic = "contains a line break"]
+fn field_names_should_reject_newlines() {
+    Point::new("m")
+        .tag("tag", "value")
+        .field("fi\neld", 1)
+        .to_line_protocol(Precision::Nanosecond)
+        .unwrap();
+}
+
+#[test]
+#[should_panic = "contains a line break"]
+fn field_values_should_reject_newlines() {
+    Point::new("m")
+        .field("field", "val\nue")
+        .to_line_protocol(Precision::Nanosecond)
+        .unwrap();
+}