4.9 KiB
Convert AutoConnectElements value to actual data type
The value of the AutoConnectElements field of the custom Web pages consists of String type for all. Sketches will need to convert them to the actual data type. And then if the data type required for processing in the sketch is not a String type, it is necessary to convert to String type when storing to the AutoConenctElements value.
AutoConnect library does not provide the data conversion utility, and its function depends on Arduino language functions or functions of the type class. However, commonly used data conversion methods are generally similar.
Here, represent examples the typical method for the data type conversion for the AutoConnectElements value of custom Web pages.
Integer
Use int() or toInt() of String.
AutoConnectInput& input = aux.getElement<AutoConnectInput>("INPUT");
int value = input.value.toInt();
Float
Use float() or toFloat() of String.
AutoConnectInput& input = aux.getElement<AutoConnectInput>("INPUT");
float value = input.value.toFloat();
Date & Time
The easiest way is to use the Arduino Time Library. Sketches must accommodate differences in date and time formats depending on the time zone. You can absorb the difference in DateTime format by using sscanf function.1
#include <TimeLib.h>
time_t tm;
int Year, Month, Day, Hour, Minute, Second;
AutoConnectInput& input = aux.getElement<AutoConnectInput>("INPUT");
sscanf(input.value.c_str(), "%d-%d-%d %d:%d:%d", &Year, &Month, &Day, &Hour, &Minute, &Second);
tm.Year = CalendarYrToTm(Year);
tm.Month = Month;
tm.Day = Day;
tm.Hour = Hour;
tm.Minute = Minute;
tm.Second = Second;
IP adderss
To convert a String to an IP address, use IPAddress::fromString. To stringize an instance of an IP address, use IPAddress::toString.
IPAddress ip;
AutoConnectInput& input aux.getElement<AutoConnectInput>("INPUT");
ip.fromString(input.value);
input.value = ip.toString();
Validation for the value
In order for data to be correctly converted from a string, the input data must be consistent with the format. How to implement strict validation in sketches depends on various perspectives and the power of tiny devices is not enough to implement a complete lexical analysis. But you can reduce the burden for data verification using the pattern of AutoConnectInput.
By giving a pattern to AutoConnectInput, you can find errors in data styles while typing in custom Web pages. The pattern is specified by regular expression. If the value during input of AutoConnectInput does not match the regular expression specified in the pattern, its background color changes to pink. Refer to Handling the custom Web pages section.
!!! caution "Regular Expressions for JavaScript" Regular expressions specified in the AutoConnectInput pattern conforms to the JavaScript specification.
Here, represent examples the typical regular expression for the input validation.
URL
^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$
DNS hostname
^(([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])$
email address 1
^[a-zA-Z0-9.!#$%&'*+\/=?^_`{|}~-]+@[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)*$
IP Address
^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$
Date as MM/DD/YYYY 2
^(0[1-9]|1[012])[- \/.](0[1-9]|[12][0-9]|3[01])[- \/.](19|20)\d\d$
!!! caution "Contain with backquote" If that regular expression contains a backquote it must be escaped by backquote duplication.