maxminddb/result.rs
1//! Lookup result types for deferred decoding.
2//!
3//! This module provides `LookupResult`, which enables lazy decoding of
4//! MaxMind DB records. Instead of immediately deserializing data, you
5//! get a lightweight handle that can be decoded later or navigated
6//! selectively via paths.
7
8use std::net::IpAddr;
9
10use ipnetwork::IpNetwork;
11use serde::Deserialize;
12
13use crate::decoder::{TYPE_ARRAY, TYPE_MAP};
14use crate::error::MaxMindDbError;
15use crate::reader::Reader;
16
17/// The result of looking up an IP address in a MaxMind DB.
18///
19/// This is a lightweight handle (~40 bytes) that stores the lookup result
20/// without immediately decoding the data. You can:
21///
22/// - Check if data exists with [`has_data()`](Self::has_data)
23/// - Get the network containing the IP with [`network()`](Self::network)
24/// - Decode the full record with [`decode()`](Self::decode)
25/// - Decode a specific path with [`decode_path()`](Self::decode_path)
26///
27/// # Example
28///
29/// ```
30/// use maxminddb::{geoip2, path, Reader};
31/// use std::net::IpAddr;
32///
33/// let reader = Reader::open_readfile("test-data/test-data/GeoIP2-City-Test.mmdb").unwrap();
34/// let ip: IpAddr = "89.160.20.128".parse().unwrap();
35///
36/// let result = reader.lookup(ip).unwrap();
37///
38/// if result.has_data() {
39/// // Full decode
40/// let city: geoip2::City = result.decode().unwrap().unwrap();
41///
42/// // Or selective decode via path
43/// let country_code: Option<String> = result
44/// .decode_path(&path!["country", "iso_code"])
45/// .unwrap();
46/// println!("Country: {:?}", country_code);
47/// }
48/// ```
49#[derive(Debug, Clone, Copy)]
50pub struct LookupResult<'a, S: AsRef<[u8]>> {
51 reader: &'a Reader<S>,
52 /// Offset into the data section, or None if not found.
53 data_offset: Option<usize>,
54 prefix_len: u8,
55 ip: IpAddr,
56 source: LookupSource,
57 network_kind: NetworkKind,
58}
59
60#[derive(Debug, Clone, Copy, PartialEq, Eq)]
61pub(crate) enum LookupSource {
62 Lookup,
63 Iter,
64}
65
66#[derive(Debug, Clone, Copy, PartialEq, Eq)]
67pub(crate) enum NetworkKind {
68 V4,
69 V6,
70 V4InV6Subtree,
71}
72
73impl<'a, S: AsRef<[u8]>> LookupResult<'a, S> {
74 #[inline]
75 fn decoder(&self, offset: usize) -> super::decoder::Decoder<'a> {
76 let buf = &self.reader.buf.as_ref()[self.reader.pointer_base..];
77 super::decoder::Decoder::new_with_limit(buf, offset, self.reader.data_section_len)
78 }
79
80 /// Creates a new LookupResult for a found IP.
81 pub(crate) fn new_found(
82 reader: &'a Reader<S>,
83 data_offset: usize,
84 prefix_len: u8,
85 ip: IpAddr,
86 source: LookupSource,
87 network_kind: NetworkKind,
88 ) -> Self {
89 LookupResult {
90 reader,
91 data_offset: Some(data_offset),
92 prefix_len,
93 ip,
94 source,
95 network_kind,
96 }
97 }
98
99 /// Creates a new LookupResult for an IP not in the database.
100 pub(crate) fn new_not_found(
101 reader: &'a Reader<S>,
102 prefix_len: u8,
103 ip: IpAddr,
104 source: LookupSource,
105 network_kind: NetworkKind,
106 ) -> Self {
107 LookupResult {
108 reader,
109 data_offset: None,
110 prefix_len,
111 ip,
112 source,
113 network_kind,
114 }
115 }
116
117 /// Returns true if the database contains data for this IP address.
118 ///
119 /// Note that `false` means the database has no data for this IP,
120 /// which is different from an error during lookup.
121 #[inline]
122 pub fn has_data(&self) -> bool {
123 self.data_offset.is_some()
124 }
125
126 /// Returns the network containing the looked-up IP address.
127 ///
128 /// This is the most specific network in the database that contains
129 /// the IP, regardless of whether data was found.
130 ///
131 /// The returned network preserves the IP version of the original lookup:
132 /// - IPv4 lookups return IPv4 networks (unless the match occurs before the
133 /// IPv4 subtree begins, see below)
134 /// - IPv6 lookups return IPv6 networks (including IPv4-mapped addresses)
135 ///
136 /// Special case: If an IPv4 address is looked up in an IPv6 database but
137 /// the matching record is above the IPv4 subtree (e.g., a database with
138 /// no IPv4 subtree), an IPv6 network is returned since there's no valid
139 /// IPv4 representation.
140 pub fn network(&self) -> Result<IpNetwork, MaxMindDbError> {
141 let (ip, prefix) = match (self.source, self.network_kind, self.ip) {
142 (_, NetworkKind::V4, IpAddr::V4(v4)) => (IpAddr::V4(v4), self.prefix_len),
143 (_, NetworkKind::V4InV6Subtree, IpAddr::V4(v4)) => (
144 IpAddr::V4(v4),
145 self.prefix_len - self.reader.ipv4_start_bit_depth as u8,
146 ),
147 (LookupSource::Lookup, NetworkKind::V6, IpAddr::V4(_)) => {
148 use std::net::Ipv6Addr;
149 (IpAddr::V6(Ipv6Addr::UNSPECIFIED), self.prefix_len)
150 }
151 (_, NetworkKind::V6, IpAddr::V6(v6)) => (IpAddr::V6(v6), self.prefix_len),
152 (_, _, ip) => unreachable!("unexpected lookup result state for network: {ip:?}"),
153 };
154
155 // Mask the IP to the network address
156 let network_ip = mask_ip(ip, prefix);
157 IpNetwork::new(network_ip, prefix).map_err(MaxMindDbError::InvalidNetwork)
158 }
159
160 /// Returns the data section offset if found, for use as a cache key.
161 ///
162 /// Multiple IP addresses often point to the same data record. This
163 /// offset can be used to deduplicate decoding or cache results.
164 ///
165 /// Returns `None` if the IP was not found.
166 #[inline]
167 pub fn offset(&self) -> Option<usize> {
168 self.data_offset
169 }
170
171 /// Decodes the full record into the specified type.
172 ///
173 /// Returns:
174 /// - `Ok(Some(T))` if found and successfully decoded
175 /// - `Ok(None)` if the IP was not found in the database
176 /// - `Err(...)` if decoding fails
177 ///
178 /// # Example
179 ///
180 /// ```
181 /// use maxminddb::{Reader, geoip2};
182 /// use std::net::IpAddr;
183 ///
184 /// let reader = Reader::open_readfile("test-data/test-data/GeoIP2-City-Test.mmdb").unwrap();
185 /// let ip: IpAddr = "89.160.20.128".parse().unwrap();
186 ///
187 /// let result = reader.lookup(ip).unwrap();
188 /// if let Some(city) = result.decode::<geoip2::City>()? {
189 /// println!("Found city data");
190 /// }
191 /// # Ok::<(), maxminddb::MaxMindDbError>(())
192 /// ```
193 pub fn decode<T>(&self) -> Result<Option<T>, MaxMindDbError>
194 where
195 T: Deserialize<'a>,
196 {
197 let Some(offset) = self.data_offset else {
198 return Ok(None);
199 };
200
201 let mut decoder = self.decoder(offset);
202 T::deserialize(&mut decoder).map(Some)
203 }
204
205 /// Decodes a value at a specific path within the record.
206 ///
207 /// Returns:
208 /// - `Ok(Some(T))` if the path exists and was successfully decoded
209 /// - `Ok(None)` if the path doesn't exist (key missing, index out of bounds)
210 /// - `Err(...)` if there's a type mismatch during navigation (e.g., `Key` on an array)
211 ///
212 /// If `has_data() == false`, returns `Ok(None)`.
213 ///
214 /// # Path Elements
215 ///
216 /// - `PathElement::Key("name")` - Navigate into a map by key
217 /// - `PathElement::Index(0)` - Navigate into an array by index (0 = first element)
218 /// - `PathElement::IndexFromEnd(0)` - Navigate from the end (0 = last element)
219 ///
220 /// # Example
221 ///
222 /// ```
223 /// use maxminddb::{path, Reader};
224 /// use std::net::IpAddr;
225 ///
226 /// let reader = Reader::open_readfile("test-data/test-data/GeoIP2-City-Test.mmdb").unwrap();
227 /// let ip: IpAddr = "89.160.20.128".parse().unwrap();
228 ///
229 /// let result = reader.lookup(ip).unwrap();
230 ///
231 /// // Navigate to country.iso_code
232 /// let iso_code: Option<String> = result
233 /// .decode_path(&path!["country", "iso_code"])
234 /// .unwrap();
235 ///
236 /// // Navigate to subdivisions[0].names.en
237 /// let subdiv_name: Option<String> = result
238 /// .decode_path(&path!["subdivisions", 0, "names", "en"])
239 /// .unwrap();
240 /// ```
241 pub fn decode_path<T>(&self, path: &[PathElement<'_>]) -> Result<Option<T>, MaxMindDbError>
242 where
243 T: Deserialize<'a>,
244 {
245 let Some(offset) = self.data_offset else {
246 return Ok(None);
247 };
248
249 let mut decoder = self.decoder(offset);
250
251 // Navigate through the path, tracking position for error context
252 for (i, element) in path.iter().enumerate() {
253 // Closure to add path context to errors during navigation.
254 // Shows path up to and including the current element where the error occurred.
255 let with_path = |e| add_path_context(e, &path[..=i]);
256
257 match *element {
258 PathElement::Key(key) => {
259 let header_offset = decoder.offset();
260 let (size, type_num) = decoder.consume_container_header().map_err(with_path)?;
261 if type_num != TYPE_MAP {
262 return Err(container_type_mismatch(
263 type_num,
264 header_offset,
265 &path[..=i],
266 format!("expected map for Key(\"{key}\"), got type {type_num}"),
267 ));
268 }
269
270 let mut found = false;
271 let key_bytes = key.as_bytes();
272 for _ in 0..size {
273 let k = decoder.read_str_as_bytes().map_err(with_path)?;
274 if k == key_bytes {
275 found = true;
276 break;
277 } else {
278 decoder.skip_value().map_err(with_path)?;
279 }
280 }
281
282 if !found {
283 decoder.validate_skip_end().map_err(with_path)?;
284 return Ok(None);
285 }
286 }
287 PathElement::Index(idx) | PathElement::IndexFromEnd(idx) => {
288 let header_offset = decoder.offset();
289 let (size, type_num) = decoder.consume_container_header().map_err(with_path)?;
290 if type_num != TYPE_ARRAY {
291 let elem = match *element {
292 PathElement::Index(i) => format!("Index({i})"),
293 PathElement::IndexFromEnd(i) => format!("IndexFromEnd({i})"),
294 PathElement::Key(_) => unreachable!(),
295 };
296 return Err(container_type_mismatch(
297 type_num,
298 header_offset,
299 &path[..=i],
300 format!("expected array for {elem}, got type {type_num}"),
301 ));
302 }
303
304 if idx >= size {
305 return Ok(None); // Out of bounds
306 }
307
308 let actual_idx = match *element {
309 PathElement::Index(i) => i,
310 PathElement::IndexFromEnd(i) => size - 1 - i,
311 PathElement::Key(_) => unreachable!(),
312 };
313
314 // Skip to the target index
315 for _ in 0..actual_idx {
316 decoder.skip_value().map_err(with_path)?;
317 }
318 }
319 }
320 }
321
322 // Decode the value at the current position
323 T::deserialize(&mut decoder)
324 .map(Some)
325 .map_err(|e| add_path_context(e, path))
326 }
327}
328
329#[cold]
330fn container_type_mismatch(
331 type_num: usize,
332 offset: usize,
333 path: &[PathElement<'_>],
334 message: String,
335) -> MaxMindDbError {
336 if type_num > usize::from(u8::MAX) {
337 MaxMindDbError::invalid_database_at(format!("unknown data type: {type_num}"), offset)
338 } else {
339 MaxMindDbError::decoding_at_path(message, offset, render_path(path))
340 }
341}
342
343/// Adds path context to a Decoding error if it doesn't already have one.
344fn add_path_context(err: MaxMindDbError, path: &[PathElement<'_>]) -> MaxMindDbError {
345 match err {
346 MaxMindDbError::Decoding {
347 message,
348 offset,
349 path: None,
350 } => MaxMindDbError::Decoding {
351 message,
352 offset,
353 path: Some(render_path(path)),
354 },
355 _ => err,
356 }
357}
358
359/// Renders path elements as a JSON-pointer-like string (e.g., "/city/names/0").
360fn render_path(path: &[PathElement<'_>]) -> String {
361 use std::fmt::Write;
362 let mut s = String::new();
363 for elem in path {
364 s.push('/');
365 match elem {
366 PathElement::Key(k) => s.push_str(k),
367 PathElement::Index(i) => write!(s, "{i}").unwrap(),
368 PathElement::IndexFromEnd(i) => write!(s, "-{}", (*i as u128) + 1).unwrap(),
369 }
370 }
371 s
372}
373
374/// A path element for navigating into nested data structures.
375///
376/// Used with [`LookupResult::decode_path()`] to selectively decode
377/// specific fields without parsing the entire record.
378///
379/// # Creating Path Elements
380///
381/// You can create path elements directly or use the [`path!`](crate::path) macro
382/// for a more convenient syntax:
383///
384/// ```
385/// use maxminddb::{path, PathElement};
386///
387/// // Direct construction
388/// let path = [PathElement::Key("country"), PathElement::Key("iso_code")];
389///
390/// // Using the macro - string literals become Keys, integers become Indexes
391/// let path = path!["country", "iso_code"];
392/// let path = path!["subdivisions", 0, "names"]; // Mixed keys and indexes
393/// let path = path!["array", -1]; // Negative indexes count from the end
394/// ```
395#[derive(Debug, Clone, PartialEq, Eq)]
396pub enum PathElement<'a> {
397 /// Navigate into a map by key.
398 Key(&'a str),
399 /// Navigate into an array by index (0-based from the start).
400 ///
401 /// - `Index(0)` - first element
402 /// - `Index(1)` - second element
403 Index(usize),
404 /// Navigate into an array by index from the end.
405 ///
406 /// - `IndexFromEnd(0)` - last element
407 /// - `IndexFromEnd(1)` - second-to-last element
408 IndexFromEnd(usize),
409}
410
411impl<'a> From<&'a str> for PathElement<'a> {
412 fn from(s: &'a str) -> Self {
413 PathElement::Key(s)
414 }
415}
416
417impl From<i32> for PathElement<'_> {
418 /// Converts an integer to a path element.
419 ///
420 /// - Non-negative values become `Index(n)`
421 /// - Negative values become `IndexFromEnd(-n - 1)`, so `-1` is the last element
422 fn from(n: i32) -> Self {
423 signed_index_to_path_element(n as isize)
424 }
425}
426
427impl From<usize> for PathElement<'_> {
428 fn from(n: usize) -> Self {
429 PathElement::Index(n)
430 }
431}
432
433impl From<isize> for PathElement<'_> {
434 /// Converts a signed integer to a path element.
435 ///
436 /// - Non-negative values become `Index(n)`
437 /// - Negative values become `IndexFromEnd(-n - 1)`, so `-1` is the last element
438 /// - `isize::MIN` saturates to `IndexFromEnd(usize::MAX)` because its
439 /// absolute value is unrepresentable as `isize`
440 fn from(n: isize) -> Self {
441 signed_index_to_path_element(n)
442 }
443}
444
445fn signed_index_to_path_element<'a>(n: isize) -> PathElement<'a> {
446 if n >= 0 {
447 PathElement::Index(n as usize)
448 } else {
449 let index = n
450 .checked_neg()
451 .and_then(|n| n.checked_sub(1))
452 .map(|n| n as usize)
453 .unwrap_or(usize::MAX);
454 PathElement::IndexFromEnd(index)
455 }
456}
457
458/// Creates a path for use with [`LookupResult::decode_path()`](crate::LookupResult::decode_path).
459///
460/// This macro provides a convenient way to construct paths with mixed string keys
461/// and integer indexes.
462///
463/// # Syntax
464///
465/// - String literals become [`PathElement::Key`]
466/// - Non-negative integers become [`PathElement::Index`]
467/// - Negative integers become [`PathElement::IndexFromEnd`] (e.g., `-1` is the last element)
468///
469/// # Examples
470///
471/// ```
472/// use maxminddb::{Reader, path};
473/// use std::net::IpAddr;
474///
475/// let reader = Reader::open_readfile("test-data/test-data/GeoIP2-City-Test.mmdb").unwrap();
476/// let ip: IpAddr = "89.160.20.128".parse().unwrap();
477/// let result = reader.lookup(ip).unwrap();
478///
479/// // Navigate to country.iso_code
480/// let iso_code: Option<String> = result.decode_path(&path!["country", "iso_code"]).unwrap();
481///
482/// // Navigate to subdivisions[0].names.en
483/// let subdiv: Option<String> = result.decode_path(&path!["subdivisions", 0, "names", "en"]).unwrap();
484/// ```
485///
486/// ```
487/// use maxminddb::{Reader, path};
488/// use std::net::IpAddr;
489///
490/// let reader = Reader::open_readfile("test-data/test-data/MaxMind-DB-test-decoder.mmdb").unwrap();
491/// let ip: IpAddr = "::1.1.1.0".parse().unwrap();
492/// let result = reader.lookup(ip).unwrap();
493///
494/// // Access the last element of an array
495/// let last: Option<u32> = result.decode_path(&path!["array", -1]).unwrap();
496/// assert_eq!(last, Some(3));
497///
498/// // Access the second-to-last element
499/// let second_to_last: Option<u32> = result.decode_path(&path!["array", -2]).unwrap();
500/// assert_eq!(second_to_last, Some(2));
501/// ```
502#[macro_export]
503macro_rules! path {
504 ($($elem:expr),* $(,)?) => {
505 [$($crate::PathElement::from($elem)),*]
506 };
507}
508
509/// Masks an IP address to its network address given a prefix length.
510fn mask_ip(ip: IpAddr, prefix: u8) -> IpAddr {
511 match ip {
512 IpAddr::V4(v4) => {
513 if prefix >= 32 {
514 IpAddr::V4(v4)
515 } else {
516 let int: u32 = v4.into();
517 let mask = if prefix == 0 {
518 0
519 } else {
520 !0u32 << (32 - prefix)
521 };
522 IpAddr::V4((int & mask).into())
523 }
524 }
525 IpAddr::V6(v6) => {
526 if prefix >= 128 {
527 IpAddr::V6(v6)
528 } else {
529 let int: u128 = v6.into();
530 let mask = if prefix == 0 {
531 0
532 } else {
533 !0u128 << (128 - prefix)
534 };
535 IpAddr::V6((int & mask).into())
536 }
537 }
538 }
539}
540
541#[cfg(test)]
542mod tests {
543 use super::*;
544
545 #[test]
546 fn test_mask_ipv4() {
547 let ip: IpAddr = "192.168.1.100".parse().unwrap();
548 assert_eq!(mask_ip(ip, 24), "192.168.1.0".parse::<IpAddr>().unwrap());
549 assert_eq!(mask_ip(ip, 16), "192.168.0.0".parse::<IpAddr>().unwrap());
550 assert_eq!(mask_ip(ip, 32), "192.168.1.100".parse::<IpAddr>().unwrap());
551 assert_eq!(mask_ip(ip, 0), "0.0.0.0".parse::<IpAddr>().unwrap());
552 }
553
554 #[test]
555 fn test_mask_ipv6() {
556 let ip: IpAddr = "2001:db8:85a3::8a2e:370:7334".parse().unwrap();
557 assert_eq!(
558 mask_ip(ip, 64),
559 "2001:db8:85a3::".parse::<IpAddr>().unwrap()
560 );
561 assert_eq!(mask_ip(ip, 32), "2001:db8::".parse::<IpAddr>().unwrap());
562 }
563
564 #[test]
565 fn test_path_element_debug() {
566 assert_eq!(format!("{:?}", PathElement::Key("test")), "Key(\"test\")");
567 assert_eq!(format!("{:?}", PathElement::Index(5)), "Index(5)");
568 assert_eq!(
569 format!("{:?}", PathElement::IndexFromEnd(0)),
570 "IndexFromEnd(0)"
571 );
572 }
573
574 #[test]
575 fn test_path_element_from_str() {
576 let elem: PathElement = "key".into();
577 assert_eq!(elem, PathElement::Key("key"));
578 }
579
580 #[test]
581 fn test_path_element_from_i32() {
582 // Positive values become Index
583 let elem: PathElement = PathElement::from(0i32);
584 assert_eq!(elem, PathElement::Index(0));
585
586 let elem: PathElement = PathElement::from(5i32);
587 assert_eq!(elem, PathElement::Index(5));
588
589 // Negative values become IndexFromEnd
590 // -1 → IndexFromEnd(0) (last element)
591 let elem: PathElement = PathElement::from(-1i32);
592 assert_eq!(elem, PathElement::IndexFromEnd(0));
593
594 // -2 → IndexFromEnd(1) (second-to-last)
595 let elem: PathElement = PathElement::from(-2i32);
596 assert_eq!(elem, PathElement::IndexFromEnd(1));
597
598 // -3 → IndexFromEnd(2)
599 let elem: PathElement = PathElement::from(-3i32);
600 assert_eq!(elem, PathElement::IndexFromEnd(2));
601 }
602
603 #[test]
604 fn test_path_element_from_usize() {
605 let elem: PathElement = PathElement::from(0usize);
606 assert_eq!(elem, PathElement::Index(0));
607
608 let elem: PathElement = PathElement::from(42usize);
609 assert_eq!(elem, PathElement::Index(42));
610 }
611
612 #[test]
613 fn test_path_element_from_isize() {
614 let elem: PathElement = PathElement::from(0isize);
615 assert_eq!(elem, PathElement::Index(0));
616
617 let elem: PathElement = PathElement::from(-1isize);
618 assert_eq!(elem, PathElement::IndexFromEnd(0));
619
620 let elem: PathElement = PathElement::from(isize::MIN);
621 assert_eq!(elem, PathElement::IndexFromEnd(usize::MAX));
622 }
623
624 #[test]
625 fn test_path_macro_keys_only() {
626 let p = path!["country", "iso_code"];
627 assert_eq!(p.len(), 2);
628 assert_eq!(p[0], PathElement::Key("country"));
629 assert_eq!(p[1], PathElement::Key("iso_code"));
630 }
631
632 #[test]
633 fn test_path_macro_mixed() {
634 let p = path!["subdivisions", 0, "names", "en"];
635 assert_eq!(p.len(), 4);
636 assert_eq!(p[0], PathElement::Key("subdivisions"));
637 assert_eq!(p[1], PathElement::Index(0));
638 assert_eq!(p[2], PathElement::Key("names"));
639 assert_eq!(p[3], PathElement::Key("en"));
640 }
641
642 #[test]
643 fn test_path_macro_negative_indexes() {
644 let p = path!["array", -1];
645 assert_eq!(p.len(), 2);
646 assert_eq!(p[0], PathElement::Key("array"));
647 assert_eq!(p[1], PathElement::IndexFromEnd(0)); // last element
648
649 let p = path!["data", -2, "value"];
650 assert_eq!(p[1], PathElement::IndexFromEnd(1)); // second-to-last
651 }
652
653 #[test]
654 fn test_path_macro_trailing_comma() {
655 let p = path!["a", "b",];
656 assert_eq!(p.len(), 2);
657 }
658
659 #[test]
660 fn test_path_macro_empty() {
661 let p: [PathElement; 0] = path![];
662 assert_eq!(p.len(), 0);
663 }
664
665 #[test]
666 fn test_render_path() {
667 assert_eq!(render_path(&[]), "");
668 assert_eq!(render_path(&[PathElement::Key("city")]), "/city");
669 assert_eq!(
670 render_path(&[PathElement::Key("city"), PathElement::Key("names")]),
671 "/city/names"
672 );
673 assert_eq!(
674 render_path(&[PathElement::Key("arr"), PathElement::Index(0)]),
675 "/arr/0"
676 );
677 assert_eq!(
678 render_path(&[PathElement::Key("arr"), PathElement::Index(42)]),
679 "/arr/42"
680 );
681 // IndexFromEnd(0) = last = -1, IndexFromEnd(1) = second-to-last = -2
682 assert_eq!(
683 render_path(&[PathElement::Key("arr"), PathElement::IndexFromEnd(0)]),
684 "/arr/-1"
685 );
686 assert_eq!(
687 render_path(&[PathElement::Key("arr"), PathElement::IndexFromEnd(1)]),
688 "/arr/-2"
689 );
690 assert_eq!(
691 render_path(&[PathElement::IndexFromEnd(isize::MAX as usize)]),
692 format!("/-{}", (isize::MAX as u128) + 1)
693 );
694 assert_eq!(
695 render_path(&[PathElement::IndexFromEnd(usize::MAX)]),
696 format!("/-{}", (usize::MAX as u128) + 1)
697 );
698 }
699
700 #[test]
701 fn test_decode_path_error_includes_path() {
702 use crate::Reader;
703
704 let reader = Reader::open_readfile("test-data/test-data/GeoIP2-City-Test.mmdb").unwrap();
705 let ip: IpAddr = "89.160.20.128".parse().unwrap();
706 let result = reader.lookup(ip).unwrap();
707
708 // Try to navigate with Index on a map (root is a map, not array)
709 let err = result
710 .decode_path::<String>(&[PathElement::Index(0)])
711 .unwrap_err();
712 let err_str = err.to_string();
713 assert!(
714 err_str.contains("path: /0"),
715 "error should include path context: {err_str}"
716 );
717 assert!(
718 err_str.contains("expected array"),
719 "error should mention expected type: {err_str}"
720 );
721
722 // Try to navigate deeper and fail at second element
723 let err = result
724 .decode_path::<String>(&[PathElement::Key("city"), PathElement::Index(0)])
725 .unwrap_err();
726 let err_str = err.to_string();
727 assert!(
728 err_str.contains("path: /city/0"),
729 "error should include full path to failure: {err_str}"
730 );
731 }
732
733 #[test]
734 fn test_overflowing_extended_navigation_type_is_invalid_database() {
735 let err = container_type_mismatch(
736 256,
737 7,
738 &[PathElement::Key("city")],
739 "unused mismatch".to_owned(),
740 );
741
742 assert!(matches!(err, MaxMindDbError::InvalidDatabase { .. }));
743 assert!(err.to_string().contains("unknown data type: 256"));
744 }
745}