10000 Rewrote example JsonHttpClient.ino (fixes #600) · adamwgray/ArduinoJson@126f7ab · GitHub
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Rewrote example JsonHttpClient.ino (fixes bblanchon#600)
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‎CHANGELOG.md

Lines changed: 7 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -1,6 +1,10 @@
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ArduinoJson: change log
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=======================
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HEAD
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----
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* Rewrote example `JsonHttpClient.ino` (issue #600)
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48
v5.11.2
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-------
610

@@ -45,20 +49,20 @@ v5.10.0
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### BREAKING CHANGES :warning:
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| Old syntax | New syntax |
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|---------------------------------|---------------------|
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|:--------------------------------|:--------------------|
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| `double_with_n_digits(3.14, 2)` | `3.14` |
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| `float_with_n_digits(3.14, 2)` | `3.14f` |
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| `obj.set("key", 3.14, 2)` | `obj["key"] = 3.14` |
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| `arr.add(3.14, 2)` | `arr.add(3.14)` |
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| Input | Old output | New output |
55-
|-----------|------------|------------|
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|:----------|:-----------|:-----------|
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| `3.14159` | `3.14` | `3.14159` |
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| `42.0` | `42.00` | `42` |
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| `0.0` | `0.00` | `0` |
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| Expression | Old result | New result |
61-
|--------------------------------|------------|------------|
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|:-------------------------------|:-----------|:-----------|
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| `JsonVariant(42).is<int>()` | `true` | `true` |
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| `JsonVariant(42).is<float>()` | `false` | `true` |
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| `JsonVariant(42).is<double>()` | `false` | `true` |

‎examples/JsonHttpClient/JsonHttpClient.ino

Lines changed: 58 additions & 153 deletions
Original file line numberDiff line numberDiff line change
@@ -1,181 +1,86 @@
1-
// Sample Arduino Json Web Client
2-
// Downloads and parse http://jsonplaceholder.typicode.com/users/1
3-
//
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// ArduinoJson - arduinojson.org
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// Copyright Benoit Blanchon 2014-2017
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// MIT License
4+
//
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// Example of an HTTP client parsing a JSON response.
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//
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// This program perform an HTTP GET of arduinojson.org/example.json
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// Here is the expected response:
9+
// {
10+
// "sensor": "gps",
11+
// "time": 1351824120,
12+
// "data": [
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// 48.756080,
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// 2.302038
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// ]
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// }
17+
// See http://arduinojson.org/assistant/ to compute the size of the buffer.
18+
//
19+
// Disclaimer: the code emphasize the communication between client and server,
20+
// it doesn't claim to be a reference of good coding practices.
721

822
#include <ArduinoJson.h>
923
#include <Ethernet.h>
1024
#include <SPI.h>
1125

12-
EthernetClient client;
13-
14-
const char* server = "jsonplaceholder.typicode.com"; // server's address
15-
const char* resource = "/users/1"; // http resource
16-
const unsigned long BAUD_RATE = 9600; // serial connection speed
17-
const unsigned long HTTP_TIMEOUT = 10000; // max respone time from server
18-
const size_t MAX_CONTENT_SIZE = 512; // max size of the HTTP response
19-
20-
// The type of data that we want to extract from the page
21-
struct UserData {
22-
char name[32];
23-
char company[32];
24-
};
25-
26-
// ARDUINO entry point #1: runs once when you press reset or power the board
2726
void setup() {
28-
initSerial();
29-
initEthernet();
30-
}
27+
Serial.begin(9600);
28+
while (!Serial);
3129

32-
// ARDUINO entry point #2: runs over and over again forever
33-
void loop() {
34-
if (connect(server)) {
35-
if (sendRequest(server, resource) && skipResponseHeaders()) {
36-
UserData userData;
37-
if (readReponseContent(&userData)) {
38-
printUserData(&userData);
39-
}
40-
}
41-
}
42-
disconnect();
43-
wait();
44-
}
45-
46-
// Initialize Serial port
47-
void initSerial() {
48-
Serial.begin(BAUD_RATE);
49-
while (!Serial) {
50-
; // wait for serial port to initialize
51-
}
52-
Serial.println("Serial ready");
53-
}
54-
55-
// Initialize Ethernet library
56-
void initEthernet() {
30+
echo("Initialize Ethernet library");
5731
byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
58-
if (!Ethernet.begin(mac)) {
59-
Serial.println("Failed to configure Ethernet");
60-
return;
61-
}
62-
Serial.println("Ethernet ready");
32+
Ethernet.begin(mac) || die("Failed to configure Ethernet");
6333
delay(1000);
64-
}
6534

66-
// Open connection to the HTTP server
67-
bool connect(const char* hostName) {
68-
Serial.print("Connect to ");
69-
Serial.println(hostName);
35+
echo("Connect to HTTP server");
36+
EthernetClient client;
37+
client.setTimeout(10000);
38+
client.connect("arduinojson.org", 80) || die("Connection failed");
7039

71-
bool ok = client.connect(hostName, 80);
72-
73-
Serial.println(ok ? "Connected" : "Connection Failed!");
74-
return ok;
75-
}
76-
77-
// Send the HTTP GET request to the server
78-
bool sendRequest(const char* host, const char* resource) {
79-
Serial.print("GET ");
80-
Serial.println(resource);
81-
82-
client.print("GET ");
83-
client.print(resource);
84-
client.println(" HTTP/1.0");
85-
client.print("Host: ");
86-
client.println(host);
40+
echo("Send HTTP request");
41+
client.println("GET /example.json HTTP/1.0");
42+
client.println("Host: arduinojson.org");
8743
client.println("Connection: close");
88-
client.println();
89-
90-
return true;
91-
}
92-
93-
// Skip HTTP headers so that we are at the beginning of the response's body
94-
bool skipResponseHeaders() {
95-
// HTTP headers end with an empty line
96-
char endOfHeaders[] = "\r\n\r\n";
97-
98-
client.setTimeout(HTTP_TIMEOUT);
99-
bool ok = client.find(endOfHeaders);
100-
101-
if (!ok) {
102-
Serial.println("No response or invalid response!");
44+
client.println() || die("Failed to send request");
45+
46+
echo("Check HTTP status");
47+
char status[32] = {0};
48+
client.readBytesUntil('\r', status, sizeof(status));
49+
if (strcmp(status, "HTTP/1.1 200 OK") != 0) {
50+
echo(status);
51+
die("Unexpected HTTP response");
10352
}
10453

105-
return ok;
106-
}
107-
108-
// Parse the JSON from the input string and extract the interesting values
109-
// Here is the JSON we need to parse
110-
// {
111-
// "id": 1,
112-
// "name": "Leanne Graham",
113-
// "username": "Bret",
114-
// "email": "Sincere@april.biz",
115-
// "address": {
116-
// "street": "Kulas Light",
117-
// "suite": "Apt. 556",
118-
// "city": "Gwenborough",
119-
// "zipcode": "92998-3874",
120-
// "geo": {
121-
// "lat": "-37.3159",
122-
// "lng": "81.1496"
123-
// }
124-
// },
125-
// "phone": "1-770-736-8031 x56442",
126-
// "website": "hildegard.org",
127-
// "company": {
128-
// "name": "Romaguera-Crona",
129-
// "catchPhrase": "Multi-layered client-server neural-net",
130-
// "bs": "harness real-time e-markets"
131-
// }
132-
// }
133-
bool readReponseContent(struct UserData* userData) {
134-
// Compute optimal size of the JSON buffer according to what we need to parse.
135-
// See http://arduinojson.org/assistant/
136-
const size_t BUFFER_SIZE =
137-
JSON_OBJECT_SIZE(8) // the root object has 8 elements
138-
+ JSON_OBJECT_SIZE(5) // the "address" object has 5 elements
139-
+ JSON_OBJECT_SIZE(2) // the "geo" object has 2 elements
140-
+ JSON_OBJECT_SIZE(3) // the "company" object has 3 elements
141-
+ MAX_CONTENT_SIZE; // additional space for strings
54+
echo("Skip HTTP headers");
55+
char endOfHeaders[] = "\r\n\r\n";
56+
client.find(endOfHeaders) || die("Invalid response");
14257

143-
// Allocate a temporary memory pool
58+
echo("Allocate JsonBuffer");
59+
const size_t BUFFER_SIZE = JSON_OBJECT_SIZE(3) + JSON_ARRAY_SIZE(2) + 60;
14460
DynamicJsonBuffer jsonBuffer(BUFFER_SIZE);
14561

62+
echo("Parse JSON object");
14663
JsonObject& root = jsonBuffer.parseObject(client);
64+
if (!root.success()) die("Parsing failed!");
14765

148-
if (!root.success()) {
149-
Serial.println("JSON parsing failed!");
150-
return false;
151-
}
152-
153-
// Here were copy the strings we're interested in
154-
strcpy(userData->name, root["name"]);
155-
strcpy(userData->company, root["company"]["name"]);
156-
// It's not mandatory to make a copy, you could just use the pointers
157-
// Since, they are pointing inside the "content" buffer, so you need to make
158-
// sure it's still in memory when you read the string
66+
echo("Extract values");
67+
echo(root["sensor"].as<char*>());
68+
echo(root["time"].as<char*>());
69+
echo(root["data"][0].as<char*>());
70+
echo(root["data"][1].as<char*>());
15971

160-
return true;
72+
echo("Disconnect");
73+
client.stop();
16174
}
16275

163-
// Print the data extracted from the JSON
164-
void printUserData(const struct UserData* userData) {
165-
Serial.print("Name = ");
166-
Serial.println(userData->name);
167-
Serial.print("Company = ");
168-
Serial.println(userData->company);
169-
}
76+
void loop() {}
17077

171-
// Close the connection with the HTTP server
172-
void disconnect() {
173-
Serial.println("Disconnect");
174-
client.stop();
78+
void echo(const char* message) {
79+
Serial.println(message);
17580
}
17681

177-
// Pause for a 1 minute
178-
void wait() {
179-
Serial.println("Wait 60 seconds");
180-
delay(60000);
181-
}
82+
bool die(const char* message) {
83+
Serial.println(message);
84+
while (true); // loop forever
85+
return false;
86+
}

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