# Errno error code

Using some Mini programs API / Component, the exception (fail Callback / Promise reject）Error Objects in addition to those with errMsgWith a generic error code errno。

Code Examples

wx.openBluetoothAdapter({
  success (res) {
    console.log(res)
  }
  fail (err) {
    console.log(err.errno )
  }
})

# Background

errno The error code appears to solve the following problem:

• Currently Part API In the event of an error, only the error message is returned errMsg, no error code. The other part API Although there are Errcode, but did not form a uniform format specification.
• There are currently errCode of API In, different API Returned on failure errCode Different granularity. part API of errCode Too much granularity and not enough information.
• The same error in a different API in errCode Not aligned, not easy for developers to remember and process.

Therefore, we design a set of error codes with a uniform specificationerrnoTo help developers develop better debugging and handling errors.

errno Error codes have the following advantages:

• In error code format, has a unified design specification.
• Different API The corresponding error code is consistent with the same error code in.
• The error code contains API Category information to help developers locate problems quickly.
• different API The granularity of error codes in.

when Error Object at the same time errno Error code and errCode Error code,Generally in errno Error code。
follow-up errno The error code will be gradually extended to all API Interface, and replace the existing errCode Parameter that provides error information to the developer.

# Error code design

errno The error code is usually 7 Digits, No. 1 - 2 Bit identifier API The first class of interfaces, section 3 - 4 Bit identifier API The Second Level Class of Interfaces, Section 5 - 7 Bit indicates the specific error type.
For example: errno The error code is 1504003 When,15 Express API The first class of interfaces is Equipment,04 Express API The second class of interfaces is NFC，003 Represents a specific error type.
Currently connected. errno of API The categories covered by the interface include:

• First class category:00 - Universal error code
• First class category:01 - Basics
  • Secondary Category:00 - Common Base Error
  • Secondary Category:03 - To update
  • Secondary Category:09 - encryption
• First class category:06 - network
  • Secondary Category:00 - Common Network Error
  • Secondary Category:02 - Initiate a request
  • Secondary Category:03 - to download
  • Secondary Category:04 - upload
  • Secondary Category:06 - mDNS
• First class category:07 - Pay
  • Secondary Category:00 - Universal Payment Error
  • Secondary Category:01 - Payment Default Level 2 Category
• First class category:11 - Media
  • Secondary Category:07 - Real-time audio and video
• First class category:13 - file
  • Secondary Category:00 - Generic file error
  • Secondary Category:01 - File default secondary category
  • Secondary Category:02 - Fd interface
• First class category:14 - Open interface
  • Secondary Category:16 - WeChat Channels
• First class category:15 - equipment
  • Secondary Category:00 - Universal Device Error
  • Secondary Category:04 - NFC
  • Secondary Category:05 - Wi-Fi
  • Secondary Category:09 - Bluetooth Low Energy
  • Secondary Category:10 - Bluetooth
• First class category:20 - AI
  • Secondary Category:02 - Face recognition
  • Secondary Category:03 - vision kit
  • Secondary Category:04 - Machine learning

First-class and second-class names and API The category names of interface documents are generally consistent.

# Best practices

with API interface openBluetoothAdapter For example, when the Bluetooth adapter is not available, the openBluetoothAdapter Exception thrown by the interface Error Object:

"err":
{
	"errMsg": "openBluetoothAdapter:fail:not available",
	"errCode": 10001,
	"errno": 1500102
}

You can do exception handling with the following code:

wx.openBluetoothAdapter({
  success (res) {
    console.log(res)
  },
  fail (err) {
    // WeChat can not use Bluetooth, can guide the user to enable Bluetooth in the system settings
    if ( err.errno  === 1500102 ) {
        wx.showModal({
            content: WeChat cannot use Bluetooth, please go to the system settings to enable it.
        })
    }
  }
})

# Error Code List

The following are errno A list of values.