fix(plugin-mongodb): prevent crash on NaN or infinite document values (#1418) (#1423)

* fix(plugin-mongodb): prevent crash on NaN or infinite document values (#1418)

* refactor(plugin-mongodb): dedupe number handling and drop unreachable type cases in BSON flattener

Author: datlechin

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Custom and OpenAI-compatible AI providers now work when the base URL already ends in `/v1`, instead of building a doubled `/v1/v1/` path that failed. (#1400)
+- MongoDB: opening a collection no longer crashes when a document contains a NaN or infinite number. (#1418)
 
 ## [0.45.0] - 2026-05-26
 

Plugins/MongoDBDriverPlugin/BsonDocumentFlattener.swift

@@ -73,23 +73,9 @@ struct BsonDocumentFlattener {
         case let str as String:
             return str
         case let num as NSNumber:
-            // Check if it's a boolean (NSNumber wraps booleans too)
-            if CFBooleanGetTypeID() == CFGetTypeID(num) {
-                return num.boolValue ? "true" : "false"
-            }
-            return num.stringValue
-        case let int as Int:
-            return String(int)
-        case let int32 as Int32:
-            return String(int32)
-        case let int64 as Int64:
-            return String(int64)
-        case let double as Double:
-            return String(double)
-        case let bool as Bool:
-            return bool ? "true" : "false"
+            return displayString(for: num)
         case let date as Date:
-            return ISO8601DateFormatter().string(from: date)
+            return iso8601Formatter.string(from: date)
         case let data as Data:
             return formatBinaryData(data)
         case let dict as [String: Any]:
@@ -121,24 +107,20 @@ struct BsonDocumentFlattener {
     /// Serialize a dictionary or array to compact JSON string
     static func serializeToJson(_ value: Any) -> String {
         let sanitized = sanitizeForJson(value)
-        do {
-            let data = try JSONSerialization.data(withJSONObject: sanitized, options: [.sortedKeys])
-            if let json = String(data: data, encoding: .utf8) {
-                // Cap at 10k chars to prevent mega-document display issues
-                let nsJson = json as NSString
-                if nsJson.length > 10_000 {
-                    return String(json.prefix(10_000)) + "..."
-                }
-                return json
-            }
-        } catch {
-            // Fall through to description
+        guard JSONSerialization.isValidJSONObject(sanitized),
+              let data = try? JSONSerialization.data(withJSONObject: sanitized, options: [.sortedKeys]),
+              let json = String(data: data, encoding: .utf8) else {
+            return String(describing: value)
         }
-        return String(describing: value)
+        let nsJson = json as NSString
+        if nsJson.length > 10_000 {
+            return String(json.prefix(10_000)) + "..."
+        }
+        return json
     }
 
-    /// Recursively convert non-JSON-safe types (Data, Date, etc.) to JSON-safe representations
-    private static func sanitizeForJson(_ value: Any) -> Any {
+    /// Recursively convert every value into a JSON-safe representation
+    static func sanitizeForJson(_ value: Any) -> Any {
         switch value {
         case let dict as [String: Any]:
             return dict.mapValues { sanitizeForJson($0) }
@@ -147,12 +129,50 @@ struct BsonDocumentFlattener {
         case let data as Data:
             return formatBinaryData(data)
         case let date as Date:
-            return ISO8601DateFormatter().string(from: date)
-        default:
+            return iso8601Formatter.string(from: date)
+        case is NSNull:
             return value
+        case let str as String:
+            return str
+        case let num as NSNumber:
+            return sanitizeNumber(num)
+        default:
+            return String(describing: value)
         }
     }
 
+    private static let iso8601Formatter = ISO8601DateFormatter()
+
+    private static func displayString(for num: NSNumber) -> String {
+        if isBoolean(num) {
+            return num.boolValue ? "true" : "false"
+        }
+        if isFloatingPoint(num), !num.doubleValue.isFinite {
+            return nonFiniteToken(num.doubleValue)
+        }
+        return num.stringValue
+    }
+
+    private static func sanitizeNumber(_ num: NSNumber) -> Any {
+        guard !isBoolean(num) else { return num }
+        guard isFloatingPoint(num), !num.doubleValue.isFinite else { return num }
+        return nonFiniteToken(num.doubleValue)
+    }
+
+    private static func isBoolean(_ num: NSNumber) -> Bool {
+        CFBooleanGetTypeID() == CFGetTypeID(num)
+    }
+
+    private static func isFloatingPoint(_ num: NSNumber) -> Bool {
+        let objCType = String(cString: num.objCType)
+        return objCType == "d" || objCType == "f"
+    }
+
+    private static func nonFiniteToken(_ value: Double) -> String {
+        if value.isNaN { return "NaN" }
+        return value > 0 ? "Infinity" : "-Infinity"
+    }
+
     /// Format binary data: 16-byte values as UUID, otherwise as hex string
     private static func formatBinaryData(_ data: Data) -> String {
         if data.count == 16 {
@@ -193,27 +213,16 @@ struct BsonDocumentFlattener {
 
         switch value {
         case let num as NSNumber:
-            if CFBooleanGetTypeID() == CFGetTypeID(num) {
+            if isBoolean(num) {
                 return 8 // Boolean
             }
-            let objCType = String(cString: num.objCType)
-            if objCType == "d" || objCType == "f" {
+            if isFloatingPoint(num) {
                 return 1 // Double
             }
-            if objCType == "q" || objCType == "l" {
-                return 18 // Int64
-            }
-            return 16 // Int32
+            let objCType = String(cString: num.objCType)
+            return objCType == "q" || objCType == "l" ? 18 : 16 // Int64 : Int32
         case is String:
             return 2 // String
-        case is Bool:
-            return 8 // Boolean
-        case is Int, is Int32:
-            return 16 // Int32
-        case is Int64:
-            return 18 // Int64
-        case is Double, is Float:
-            return 1 // Double
         case is Date:
             return 9 // Date
         case is Data:

Plugins/MongoDBDriverPlugin/MongoDBPluginDriver.swift

@@ -908,7 +908,9 @@ final class MongoDBPluginDriver: PluginDatabaseDriver, @unchecked Sendable {
     }
 
     private func prettyJson(_ value: Any) -> String {
-        guard let data = try? JSONSerialization.data(withJSONObject: value, options: [.sortedKeys, .prettyPrinted]),
+        let sanitized = BsonDocumentFlattener.sanitizeForJson(value)
+        guard JSONSerialization.isValidJSONObject(sanitized),
+              let data = try? JSONSerialization.data(withJSONObject: sanitized, options: [.sortedKeys, .prettyPrinted]),
               let json = String(data: data, encoding: .utf8) else {
             return String(describing: value)
         }