HTTP request for WeChat applet development

Network communication in the WeChat applet can only communicate with the specified domain name. The WeChat applet includes four types of network requests: ordinary HTTPS requests (wx.request), upload files (wx.uploadFile), and download files. (wx.downloadFile), WebSocket communication (wx.connectSocket). Here we mainly introduce three network requests: wx.request, wx.uploadFile, and wx.dowloadFile.

For network communication in the WeChat applet, you can only communicate with the specified domain name. The WeChat applet includes four types of network requests.

• Normal HTTPS request (wx.request)

• Upload file (wx.uploadFile)

• Download file (wx.downloadFile)

• WebSocket communication (wx.connectSocket)

Here we introduce wx.request, wx.uploadFile, wx.dowloadFile mainly uses three types of network requests.

Set the domain name

If you want the WeChat applet to communicate online, you must first set the domain name, otherwise an error will occur:

The URL domain name is illegal, please Retry after mp background configuration

You need to set the domain name in the mini program of the WeChat public platform.

You can see the setting options in the setting interface of the WeChat applet:

Select development settings:

.

You can see the server settings:

Here you can set the domain names corresponding to four types of network access, each type The network request needs to set a domain name. Note that if the domain name is set to //m.sbmmt.com/, then //m.sbmmt.com/ cannot be called and must be followed by /.

http request

Use wx.request to initiate an http request. A WeChat applet is limited to only 5 network requests at the same time.

function queryRequest(data){         wx.request({         url:"https://example.com/api/",         data:data,         header:{            // "Content-Type":"application/json"         },         success:function(res){             console.log(res.data)         },         fail:function(err){             console.log(err)         }      })  }

The above code will send an http get request and then print out the returned results. The parameters are also relatively easy to understand.

• url The url address of the server

• data The requested parameters can be in the form of String data: "xxx=xxx&xxx=xxx" or Object data :{"userId":1} format

• header sets the request header

• success interface success callback

• fail interface failure callback

There are also two parameters not in the code:

• method http method , the default is GET request

• complete callback after calling the interface, regardless of success or failure, the interface will be called

Upload File

The api for uploading files is wx.uploadFile, which will initiate an http post request in which the Content-type is multipart/form-data. The server needs to receive files according to the Content-type type. Sample code:

function uploadFile(file,data) {     wx.uploadFile({         url: 'http://example.com/upload',         filePath: file,         name: 'file',         formData:data,         success:function(res){             console.log(res.data)         },         fail:function(err){             console.log(err)         }      })      }

The url, header, success, fail and complete are the same as ordinary http requests.

The parameters that differ here are:

• The key corresponding to the name file. The server needs to obtain the file through the name parameter

• formData Other parameters that can be used in the http request

Download file

The api for downloading files is wx.downloadFile, which will initiate an http get request, and returns the temporary path of the file after the download is successful. Sample code:

function downloadFile(url,typ,success){     wx.downloadFile({         url:url,         type:typ,         success:function(res){             if(success){                 success(res.tempFilePath)             }         },         fail:function(err){             console.log(err)         }     }) }

The parameters of url, header, fail, complete and wx.uploadFile are consistent, and there are different parameters. Yes:

• type: The type of downloaded resource, used for automatic identification by the client, the parameters that can be used are image/audio/video

• success : Callback after a successful download, using the tempFilePath parameter to return the temporary directory of the file: res={tempFilePath:'File Path'}

After the download is successful, it is a temporary file, which will only be The program can be used during this running time. If you need to save it permanently, you need to call the method wx.saveFile to actively persist the file. Example code:

function svaeFile(tempFile,success){     wx.saveFile({         tempFilePath:tempFile,         success:function(res){             var svaedFile=res.savedFilePath             if(success){                 success(svaeFile)             }         }     }) }

Use wx.saveFile to save the temporary file locally and provide it to the applet. Used when starting the first time, the parameters:

• tempFilePath The path of the file that needs to be saved

• success The callback for successful saving, returns the successful save Path, use res.savedFilePath to get the successfully saved path

• fail failed callback

• complete callback

Timeout setting

在微信小程序开发:MINA中已经提到了在app.js中设置networkTimeout可以设置四种类型网络访问的超时时间：

"networkTimeout":{    "request": 10000,    "connectSocket": 10000,    "uploadFile": 10000,    "downloadFile": 10000 }

这里设置的超时时间对应着四种类型的网络请求。

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