Introduction to WeChat Development (9) Local Cache-WeChat Development-php.cn

Introduction to WeChat Development (9) Local Cache

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Release： 2017-05-24 09:55:26

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Currently, WeChat provides 10M of local cache space for each mini program (oh my god, it’s so big)

With local cache, your mini program can do:

Offline application (tested to operate cached data without network)
Smooth user experience
Reduce network requests and save server resources

Which data is suitable for side cache:

Hot data
Static data (user data, server authorization ID, etc.)
Network address (network address of pictures, files, etc.)
Paging list data and detailed content

General cache systems use key-value pairs to complete data insertion and reading. By performing a Hash algorithm on key, a unique value is obtained and bound to the value; when queries, the algorithm space is queried based on the hashed key Complexity O(1);

The implementation of the local cache of the mini program is based on the above method. However, whether the data is stored in ROM or stored in RAM for persistence remains to be studied.

There are two types of local cache data operations: synchronous and asynchronous. The synchronization method has a success callback function , which indicates the operation after successful data processing. The following is the local cache operation interface provided by the mini program:

##OperationAsynchronous methodSynchronous methodInsertwx.setStoragewx.setStorageSyncReadwx.getStoragewx.getStorageSyncRemovewx.removeStoragewx.removeStorageSyncClearwx.clearStoragewx.clearStorageSync##Get cache informationAll methods ending with Sync are synchronization methods. The difference between synchronous methods and asynchronous methods is:






wx.getStorageInfo	wx.getStorageInfoSync

1. Call the asynchronous method first, and then call the synchronous method

 Page({save: function(e){console.log(&#39;开始保存&#39;)wx.setStorage({
   key: &#39;key1&#39;,
   data: &#39;data1&#39;,
   success: function(res){
    console.log(&#39;异步保存成功&#39;)  }})wx.setStorageSync(&#39;key2&#39;, &#39;data2&#39;)console.log(&#39;同步保存成功&#39;)  }})

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Execution results:

Introduction to WeChat Development (9) Local Cache It can be seen that the synchronous method is successfully saved before the asynchronous method, indicating that the asynchronous method does not block the current task.

1. First call the synchronous method, then call the asynchronous method

Page({save: function(e){console.log(&#39;开始保存&#39;)wx.setStorageSync(&#39;key2&#39;, &#39;data2&#39;)console.log(&#39;同步保存成功&#39;)wx.setStorage({
  key: &#39;key1&#39;,
  data: &#39;data1&#39;,
  success: function(res){
    console.log(&#39;异步保存成功&#39;)  }})  }})

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Execution result:

Introduction to WeChat Development (9) Local Cache It can be seen that the asynchronous method can only wait until the synchronous method is executed It will be executed only if it succeeds.

Cache

API

Provides an interface wx.getStorageInfo for obtaining local cache information. With it, developers can re-encapsulate existing APIs, such as adding cache time and inserting without overwriting. , batch deletion, determining the current cache size, etc. The last one is the issue of cache isolation level:

debugging

conditions, each mini program QR code scanning user will be allocated a 10M local cache. The above are the results obtained by personal testing on real machines. The results may not be completely accurate and are for reference only.
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