ESP8266WebServer: pathArgs() to complement pathArg(N)

similar to ::args(), returns number of parsed path arguments
shortened esp8266#9100

Author: mcspr

libraries/ESP8266WebServer/README.rst

@@ -16,10 +16,10 @@ Class Constructor
 
 Creates the ESP8266WebServer class object.
 
-*Parameters:* 
+*Parameters:*
 
 host IP address: ``IPaddress addr`` (optional)
-  
+
 host port number: ``int port`` (default is the standard HTTP port 80)
 
 Basic Operations
@@ -61,7 +61,7 @@ Client request handlers
   void onNotFound();
   void onFileUpload();	
 
-*Example:* 
+*Example:*
 
 .. code:: cpp
 
@@ -75,7 +75,7 @@ Client request filters
 ^^^^^^^^^^^^^^^^^^^^^^
 
 .. code:: cpp
-  
+
   RequestHandler<ServerType>& setFilter();
 
 *Example:*
@@ -110,10 +110,10 @@ Getting information about request arguments
 
 .. code:: cpp
 
-  const String & arg();
-  const String & argName();
+  const String & arg(int);
+  const String & argName(int);
   int args();
-  bool hasArg();
+  bool hasArg(const String&);
 
 ``arg`` - get request argument value, use ``arg("plain")`` to get POST body
 
@@ -133,14 +133,14 @@ Getting information about request headers
   const String & hostHeader();
   int headers();
   bool hasHeader();
-  
+
 
 ``header`` - get request header value
 
 ``headerName`` - get request header name
 
 ``hostHeader`` - get request host header if available, else empty string
-  
+
 ``headers`` - get header count
 
 ``hasHeader`` - check if header exist
@@ -165,20 +165,32 @@ Authentication
     server.requestAuthentication();
   }
 
+Getting information about request path arguments
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+.. code:: cpp
+
+  const String & pathArg(int) const;
+  int pathArgs() const;
+
+``pathArg`` - get request path argument by index (starting with 0)
+	
+``pathArgs`` - get path arguments count, make sure to check it before accessing ``pathArg`` value
+	
 
 Other Function Calls
 ~~~~~~~~~~~~~~~~~~~~
 
 .. code:: cpp
 
   const String & uri(); // get the current uri
-  HTTPMethod  method(); // get the current method 
+  HTTPMethod  method(); // get the current method
   WiFiClient & client(); // get the current client
   HTTPUpload & upload(); // get the current upload
   void setContentLength(); // set content length
   void sendHeader(); // send HTTP header
   void sendContent(); // send content
-  void sendContent_P(); 
+  void sendContent_P();
   void collectHeaders(); // set the request headers to collect
   void serveStatic();
   size_t streamFile();

libraries/ESP8266WebServer/examples/PathArgServer/PathArgServer.ino

@@ -16,6 +16,15 @@ const char *password = STAPSK;
 
 ESP8266WebServer server(80);
 
+bool checkPathArgs(int number) {
+  if (server.pathArgs() == number) {
+    return true;
+  }
+
+  server.send(500, "text/plain", "request handler received unexpected number of path arguments");
+  return false;
+}
+
 void setup(void) {
   Serial.begin(115200);
   WiFi.mode(WIFI_STA);
@@ -40,11 +49,19 @@ void setup(void) {
   });
 
   server.on(UriBraces("/users/{}"), []() {
+    if (!checkPathArgs(1)) {
+      return;
+    }
+
     String user = server.pathArg(0);
     server.send(200, "text/plain", "User: '" + user + "'");
   });
 
   server.on(UriRegex("^\\/users\\/([0-9]+)\\/devices\\/([0-9]+)$"), []() {
+    if (!checkPathArgs(2)) {
+      return;
+    }
+
     String user = server.pathArg(0);
     String device = server.pathArg(1);
     server.send(200, "text/plain", "User: '" + user + "' and Device: '" + device + "'");

libraries/ESP8266WebServer/src/ESP8266WebServer-impl.h

@@ -657,8 +657,15 @@ void ESP8266WebServerTemplate<ServerType>::_streamFileCore(const size_t fileSize
 }
 
 template <typename ServerType>
-const String& ESP8266WebServerTemplate<ServerType>::pathArg(unsigned int i) const {
+int ESP8266WebServerTemplate<ServerType>::pathArgs() const {
   if (_currentHandler != nullptr)
+    return _currentHandler->pathArgsSize();
+  return 0;
+}
+
+template <typename ServerType>
+const String& ESP8266WebServerTemplate<ServerType>::pathArg(int i) const {
+  if (i >= 0 && _currentHandler != nullptr && (size_t)i < _currentHandler->pathArgsSize())
     return _currentHandler->pathArg(i);
   return emptyString;
 }

libraries/ESP8266WebServer/src/ESP8266WebServer.h

@@ -141,7 +141,9 @@ class ESP8266WebServerTemplate
   // Allows setting server options (i.e. SSL keys) by the instantiator
   ServerType &getServer() { return _server; }
 
-  const String& pathArg(unsigned int i) const; // get request path argument by number
+  const String& pathArg(int i) const; // get request path argument by number
+  int pathArgs() const; // get path arguments count
+
   const String& arg(const String& name) const;    // get request argument value by name
   const String& arg(int i) const;          // get request argument value by number
   const String& argName(int i) const;      // get request argument name by number

libraries/ESP8266WebServer/src/detail/RequestHandler.h

@@ -3,7 +3,6 @@
 
 #include <ESP8266WebServer.h>
 #include <vector>
-#include <assert.h>
 
 namespace esp8266webserver {
 
@@ -16,7 +15,7 @@ class RequestHandler {
     /*
         note: old handler API for backward compatibility
     */
-    
+
     virtual bool canHandle(HTTPMethod method, const String& uri) {
         (void) method;
         (void) uri;
@@ -43,7 +42,7 @@ class RequestHandler {
         return false;
     }
     virtual bool handle(WebServerType& server, HTTPMethod requestMethod, const String& requestUri) {
-        (void) server; 
+        (void) server;
         (void) requestMethod;
         (void) requestUri;
         return false;
@@ -74,8 +73,11 @@ class RequestHandler {
     std::vector<String> pathArgs;
 
 public:
-    const String& pathArg(unsigned int i) { 
-        assert(i < pathArgs.size());
+    size_t pathArgsSize() const {
+        return pathArgs.size();
+    }
+
+    const String& pathArg(unsigned int i) const {
         return pathArgs[i];
     }
 };