AutoConnect/mkdocs/wojson.md

Suppress increase in memory consumption

Custom Web page processing consumes a lot of memory. AutoConnect will take a whole string of the JSON document for the custom Web pages into memory. The required buffer size for the JSON document of example sketch mqttRSSI reaches approximately 3000 bytes. And actually, it needs twice the heap area. Especially this constraint will be a problem with the ESP8266 which has a heap size poor.

AutoConnect can handle custom Web pages without using JSON. In that case, since the ArduinoJson library will not be bound, the sketch size will also be reduced.

Writing the custom Web pages without JSON

To handle the custom Web pages without using JSON, follow the steps below.

1. Create or define AutoConnectAux for each page.
2. Create or define AutoConnectElement(s).
3. Add AutoConnectElement(s) to AutoConnectAux.
4. Create more AutoConnectAux containing AutoConnectElement(s), if necessary.
5. Register the request handlers for the custom Web pages.
6. Join prepared AutoConnectAux(s) to AutoConnect.
7. Invoke AutoConnect::begin().

In addition to the above procedure, to completely cut off for binding with the ArduinoJson library, turn off the ArduinoJson use indicator which is declared by the AutoConnect definitions. Its declaration is in AutoConnectDefs.h file.¹

// Comment out the AUTOCONNECT_USE_JSON macro to detach the ArduinoJson.
#define AUTOCONNECT_USE_JSON

!!! caution "JSON processing will be disabled" Commenting out the AUTOCONNECT_USE_JSON macro invalidates all functions related to JSON processing. If the sketch is using the JSON function, it will result in a compile error.

Implementation example without ArduinoJson

The code excluding JSON processing from the mqttRSSI sketch attached to the library is as follows. (It is a part of code. Refer to mqttRSSI_NA.ino for the whole sketch.)

The JSON document for mqttRSSI

[
  {
    "title": "MQTT Setting",
    "uri": "/mqtt_setting",
    "menu": true,
    "element": [
      {
        "name": "header",
        "type": "ACText",
        "value": "<h2>MQTT broker settings</h2>",
        "style": "text-align:center;color:#2f4f4f;padding:10px;"
      },
      {
        "name": "caption",
        "type": "ACText",
        "value": "Publishing the WiFi signal strength to MQTT channel. RSSI value of ESP8266 to the channel created on ThingSpeak",
        "style": "font-family:serif;color:#4682b4;"
      },
      {
        "name": "mqttserver",
        "type": "ACInput",
        "value": "",
        "label": "Server",
        "pattern": "^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\\-]*[a-zA-Z0-9])\\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\\-]*[A-Za-z0-9])$",
        "placeholder": "MQTT broker server"
      },
      {
        "name": "channelid",
        "type": "ACInput",
        "label": "Channel ID",
        "pattern": "^[0-9]{6}$"
      },
      {
        "name": "userkey",
        "type": "ACInput",
        "label": "User Key"
      },
      {
        "name": "apikey",
        "type": "ACInput",
        "label": "API Key"
      },
      {
        "name": "newline",
        "type": "ACElement",
        "value": "<hr>"
      },
      {
        "name": "uniqueid",
        "type": "ACCheckbox",
        "value": "unique",
        "label": "Use APID unique",
        "checked": false
      },
      {
        "name": "period",
        "type": "ACRadio",
        "value": [
          "30 sec.",
          "60 sec.",
          "180 sec."
        ],
        "label": "Update period",
        "arrange": "vertical",
        "checked": 1
      },
      {
        "name": "newline",
        "type": "ACElement",
        "value": "<hr>"
      },
      {
        "name": "hostname",
        "type": "ACInput",
        "value": "",
        "label": "ESP host name",
        "pattern": "^([a-zA-Z0-9]([a-zA-Z0-9-])*[a-zA-Z0-9]){1,32}$"
      },
      {
        "name": "save",
        "type": "ACSubmit",
        "value": "Save&amp;Start",
        "uri": "/mqtt_save"
      },
      {
        "name": "discard",
        "type": "ACSubmit",
        "value": "Discard",
        "uri": "/"
      }
    ]
  },
  {
    "title": "MQTT Setting",
    "uri": "/mqtt_save",
    "menu": false,
    "element": [
      {
        "name": "caption",
        "type": "ACText",
        "value": "<h4>Parameters saved as:</h4>",
        "style": "text-align:center;color:#2f4f4f;padding:10px;"
      },
      {
        "name": "parameters",
        "type": "ACText"
      },
      {
        "name": "clear",
        "type": "ACSubmit",
        "value": "Clear channel",
        "uri": "/mqtt_clear"
      }
    ]
  }
]

Exclude the JSON and replace to the AutoConnectElements natively

// In the declaration,
// Declare AutoConnectElements for the page asf /mqtt_setting
ACText(header, "<h2>MQTT broker settings</h2>", "text-align:center;color:#2f4f4f;padding:10px;");
ACText(caption, "Publishing the WiFi signal strength to MQTT channel. RSSI value of ESP8266 to the channel created on ThingSpeak", "font-family:serif;color:#4682b4;");
ACInput(mqttserver, "", "Server", "^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\\-]*[a-zA-Z0-9])\\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\\-]*[A-Za-z0-9])$", "MQTT broker server");
ACInput(channelid, "", "Channel ID", "^[0-9]{6}$");
ACInput(userkey, "", "User Key");
ACInput(apikey, "", "API Key");
ACElement(newline, "<hr>");
ACCheckbox(uniqueid, "unique", "Use APID unique");
ACRadio(period, { "30 sec.", "60 sec.", "180 sec." }, "Update period", AC_Vertical, 1);
ACSubmit(save, "Start", "mqtt_save");
ACSubmit(discard, "Discard", "/");

// Declare the custom Web page as /mqtt_setting and contains the AutoConnectElements
AutoConnectAux mqtt_setting("/mqtt_setting", "MQTT Setting", true, {
  header,
  caption,
  mqttserver,
  channelid,
  userkey,
  apikey,
  newline,
  uniqueid,
  period,
  newline,
  save,
  discard
});

// Declare AutoConnectElements for the page as /mqtt_save
ACText(caption2, "<h4>Parameters available as:</h4>", "text-align:center;color:#2f4f4f;padding:10px;");
ACText(parameters);
ACSubmit(clear, "Clear channel", "/mqtt_clear");

// Declare the custom Web page as /mqtt_save and contains the AutoConnectElements
AutoConnectAux mqtt_save("/mqtt_save", "MQTT Setting", false, {
  caption2,
  parameters,
  clear
});

// In the setup(),
// Join the custom Web pages and performs begin
  portal.join({ mqtt_setting, mqtt_save });
  portal.begin();

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1. Detaching the ArduinoJson library reduces the sketch size by approximately 10K bytes. ↩︎