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initial json support #43

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initial json support #43

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d48bc42
Firebase: initial json support
proppy Jan 13, 2016
bb8fe2a
update examples
proppy Jan 13, 2016
0037b01
add firebaseobject
proppy Jan 26, 2016
492014e
json: opaque FirebaseObject type
proppy Jan 27, 2016
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53 changes: 25 additions & 28 deletions Firebase.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -27,16 +27,21 @@ Firebase& Firebase::auth(const String& auth) {
return *this;
}

String Firebase::get(const String& path) {
FirebaseObject Firebase::create() {
return FirebaseObject{};
}

FirebaseObject Firebase::get(const String& path) {
return sendRequest("GET", path);
}

String Firebase::push(const String& path, const String& value) {
return sendRequest("POST", path, value);
FirebaseObject Firebase::push(const String& path, const FirebaseObject& value) {
char buffer[256];
value.json.printTo(buffer, sizeof(buffer));
return sendRequest("POST", path, buffer);
}

Firebase& Firebase::stream(const String& path) {
_error.reset();
FirebaseObject Firebase::stream(const String& path) {
String url = makeURL(path);
const char* headers[] = {"Location"};
_http.setReuse(true);
Expand All @@ -55,11 +60,11 @@ Firebase& Firebase::stream(const String& path) {
statusCode = _http.sendRequest("GET", (uint8_t*)NULL, 0);
}
if (statusCode != 200) {
_error.set(statusCode,
"stream " + location + ": "
+ HTTPClient::errorToString(statusCode));
return FirebaseObject(FirebaseError(statusCode,
"stream " + location + ": "
+ HTTPClient::errorToString(statusCode)));
}
return *this;
return FirebaseObject{};
}

String Firebase::makeURL(const String& path) {
Expand All @@ -74,19 +79,17 @@ String Firebase::makeURL(const String& path) {
return url;
}

String Firebase::sendRequest(const char* method, const String& path, const String& value) {
_error.reset();
FirebaseObject Firebase::sendRequest(const char* method, const String& path, const String& value) {
String url = makeURL(path);
_http.begin(_host.c_str(), firebasePort, url.c_str(), true, firebaseFingerprint);
int statusCode = _http.sendRequest(method, (uint8_t*)value.c_str(), value.length());
if (statusCode < 0) {
_error.set(statusCode,
String(method) + " " + url + ": "
+ HTTPClient::errorToString(statusCode));
return "";
return FirebaseObject(FirebaseError(statusCode,
String(method) + " " + url + ": "
+ HTTPClient::errorToString(statusCode)));
}
// no _http.end() because of connection reuse.
return _http.getString();
return FirebaseObject(_http.getString());
}

bool Firebase::connected() {
Expand All @@ -97,18 +100,12 @@ bool Firebase::available() {
return _http.getStreamPtr()->available();
}

Firebase::Event Firebase::read(String& event) {
FirebaseObject Firebase::read() {
auto client = _http.getStreamPtr();
Event type;;
String typeStr = client->readStringUntil('\n').substring(7);
if (typeStr == "put") {
type = Firebase::Event::PUT;
} else if (typeStr == "patch") {
type = Firebase::Event::PATCH;
} else {
type = Firebase::Event::UNKNOWN;
}
event = client->readStringUntil('\n').substring(6);
String event = client->readStringUntil('\n').substring(7);
String data = client->readStringUntil('\n').substring(6);
client->readStringUntil('\n'); // consume separator
return type;
FirebaseObject result(data);
result.json["event"] = event;
return result;
}
63 changes: 36 additions & 27 deletions Firebase.h
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Original file line number Diff line number Diff line change
Expand Up @@ -24,50 +24,59 @@
#include <ESP8266WiFi.h>
#include <WiFiClientSecure.h>
#include <ESP8266HTTPClient.h>
#include <ArduinoJson.h>

// FirebaseError represents a Firebase API error with a code and a
// message.
class FirebaseError {
// FirebaseError is an error for a given firebase API call.
struct FirebaseError {
FirebaseError() {}
FirebaseError(int c, const String& m) : code(c), message(m) {}
FirebaseError(int c, const char* m) : code(c), message(m) {}
int code = 0;
String message = "";
operator bool() const {
return code < 0;
}
};

// FirebaseObject is a payload or a result for a given firebase API call.
class FirebaseObject {
public:
operator bool() const { return _code < 0; }
int code() const { return _code; }
const String& message() const { return _message; }
void reset() { set(0, ""); }
void set(int code, const String& message) {
_code = code;
_message = message;
FirebaseObject() : json(_buf.createObject()) {
}
FirebaseObject(const String& data) : _data(data), json(_buf.parseObject((char*)_data.c_str())) {
if (!json.success()) {
error = FirebaseError{-1, "error parsing json"};
}
}
FirebaseObject(const FirebaseError& err) : error{err}, json(_buf.createObject()) {
}
private:
int _code = 0;
String _message = "";
StaticJsonBuffer<200> _buf;
String _data;
public:
FirebaseError error;
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Similar to below It seems preferable to keep error private as well and expose it as error(). While currently there is no hard reason for this one it will give us much more flexibility in the future without breaking existing implementations.

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Done.

JsonObject& json;
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Do we really want to expose this? It seems like we are exposing internal state. It is a mutable object that the client can change accidentally, when we don't actually need mutability. In addition the client needs to understand the FirebaseObject and the JasonObject. The latter is especially extra work as it involves hunting down the source for another library.

What if we keep this internal and expose the get, is, and operator[] in a immutable way.

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yes, I agree. I took a shortcut because I didn't want to duplicate the API of JsonObject up front (not only operator[] but also every cast operator for literal value).

Also nesting the JsonObject give us a way to have a result object that's either an error or some json, if we flatten it in the FirebaseObject: we could document that you need to call error() before accessing / casting anything.

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Done.

But still need to also forward the cast operators for string and number literal (and get/is).

};

// Firebase is the connection to firebase.
// Firebase is a client for a given firebase host.
class Firebase {
public:
Firebase(const String& host);
Firebase& auth(const String& auth);
const FirebaseError& error() const {
return _error;
}
String get(const String& path);
String push(const String& path, const String& value);
FirebaseObject get(const String& path);
FirebaseObject push(const String& path, const FirebaseObject& value);
bool connected();
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I still feel like the concept of being connected or available is only relevant to one usecase (the stream call) so it seems like this should all be separated from the Firebase object to keep it as simple as possible to understand for the other uses.

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Yes, for available() because the read() call is separate, but it could also be useful for a non blocking version.

connected is useful if we implement a separate warm up connect, to avoid paying an extra latency tax on the first api call.

Firebase& stream(const String& path);
FirebaseObject stream(const String& path);
bool available();
enum Event {
UNKNOWN,
PUT,
PATCH
};
Event read(String& event);
FirebaseObject read();
FirebaseObject create();
private:
String makeURL(const String& path);
String sendRequest(const char* method, const String& path, const String& value = "");
FirebaseObject sendRequest(const char* method, const String& path, const String& value = "");
HTTPClient _http;
String _host;
String _auth;
FirebaseError _error;
};


#endif // firebase_h
20 changes: 11 additions & 9 deletions examples/FirebasePush_ESP8266/FirebasePush_ESP8266.ino
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,7 @@
#include <Firebase.h>

// create firebase client.
Firebase fbase = Firebase("example.firebaseio.com")
Firebase fbase = Firebase("firebase-arduino-example.firebaseio-demo.com")
.auth("secret_or_token");

void setup() {
Expand All @@ -38,17 +38,19 @@ void setup() {
Serial.println(WiFi.localIP());

// add a new entry.
String l = fbase.push("/logs", "{\".sv\": \"timestamp\"}");
FirebaseObject obj = fbase.create();
obj.json[".sv"] = "timestamp";
FirebaseObject result = fbase.push("/logs", obj);

// handle error.
if (fbase.error()) {
Serial.println("Firebase request failed");
Serial.println(fbase.error().message());
if (result.error) {
Serial.print("firebase request failed: ");
Serial.println(result.error);
return;
}
// print response.
Serial.println(l);
// print all entries.
Serial.println(fbase.get("/logs"));

// print result.
Serial.println(result.json["name"]);
}

void loop() {
Expand Down
41 changes: 22 additions & 19 deletions examples/FirebaseStream_ESP8266/FirebaseStream_ESP8266.ino
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Original file line number Diff line number Diff line change
Expand Up @@ -48,26 +48,29 @@ void setup() {


void loop() {
if (fbase.error()) {
Serial.println("streaming error");
Serial.println(fbase.error().message());
}
if (fbase.available()) {
String event;
auto type = fbase.read(event);
Serial.print("event: ");
Serial.println(type);
if (type != Firebase::Event::UNKNOWN) {
FirebaseObject result = fbase.read();
if (result.error) {
Serial.println("firebase streaming error");
Serial.println(result.error);
return;
}
if (result.json["event"] == "put") {
String path = result.json["path"];
float data = result.json["data"];
Serial.print("path: ");
Serial.println(path);
Serial.print("data: ");
Serial.println(event);

// TODO(proppy): parse JSON object.
display.clearDisplay();
display.setTextSize(1);
display.setTextColor(WHITE);
display.setCursor(0,0);
display.println(event);
display.display();
Serial.println(data);
if (path != "/_updated") {
display.clearDisplay();
display.setTextSize(2);
display.setTextColor(WHITE);
display.setCursor(0,0);
display.println(path.c_str()+1);
display.println(data);
display.display();
}
}
}
}
}