Summary of common errors in wechat applet cloud development

 

Catalog

  One   Use API When accessing cloud database where Conditions

Two   Use API The operation of cloud database is asynchronous

3、 ... and Code package size exceeded .

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  One   Use API When accessing cloud database where Conditions

1. Use API When accessing cloud database where Conditions must not be underfind, Otherwise it will get stuck .

 db.collection('user').where({
      _openid: openId
    })

So when openId It must not be underfind. 

Two   Use API The operation of cloud database is asynchronous

2. Use API The operation of cloud database is asynchronous , At this time, the access task will be added to the opposite column , Wait for other statements below to execute first, and then operate the database . Therefore, if in the callback when operating cloud database setdata The new data , Then call in parallel under the operation database function API Operating the database , here where It can't be the new one above setdata The data of . Because the callback function has not been executed at this time .

 

Write it correctly : The second operation database should be encapsulated into a function , Call in the callback function for the first time , Or write the code directly into the first callback to execute .

      success(res) {
        if (res.confirm) {
          wx.showLoading({
            title: ' Data loading ...',
          });
          const db = wx.cloud.database({ //  Link data table 
            env: ""
          });
          // Favorite list string processing 
          var delete_id = that.data.list[e.currentTarget.dataset.index]._id
          var arrCollectionstr = that.options.collectionstr.split(',')
          var new_collectionstr = ''
          for (let index = 0; index < arrCollectionstr.length; index++) {
            if (arrCollectionstr[index] != delete_id) {
              new_collectionstr += arrCollectionstr[index]
              if (index != arrCollectionstr.length - 1) {
                new_collectionstr += ','
              }
            }
          }
          // modify user database 
          db.collection('user').where({
            _openid: that.data.openid
          }).update({
            data: {
              Collection: new_collectionstr
            },
            success: function (res) {
              wx.showToast({
                title: " Triple curtain ： Modification successful , Please reload after returning ", //  Content of tips 
                icon: "none", //  Icon , Default success
                image: "", //  The local path of the custom icon ,image  Has a higher priority than  icon
                duration: 3000, //  Delay time of prompt , Default 1500
                mask: false, //  Whether the transparent mask is displayed , Prevent touch penetration 
              })
              wx.hideLoading();
            }
          })
        }
      }

notes : If the operation is repeatable, it is recommended to package it as a function , This is convenient for later maintenance . And prevent the situation of writing continuous multi-layer dolls by operating the database .

3、 ... and Code package size exceeded .

It is recommended to put the icons with small volume directly outside the code package , All other pictures are suggested to be stored directly in the cloud , Invocation time src Directly fill in and generate as http Address , This can effectively reduce the size of the code package , Another thing to note is that images are generated when they are stored in the cloud http Address validity is related to permissions , If only the creator can read , Then the validity period is one month , If everyone can read , The term of validity is permanent .