Pouchdb 简明教程

PouchDB - Update Batch

你可以使用 bulkDocs() 方法一次更新 PouchDB 中的文档阵列。为此，你需要创建包含这些文档的阵列，每个文档包括 _id, _rev 和需更新的值。

You can update an array of documents in PouchDB at once using the bulkDocs() method. To do so you need to create an array of documents where, each document contains _id, _rev and the values that are to be updated.

假设存储在 PouchDB 本地数据库中的名为 my_database 的数据库包含 3 个文档，即 doc1、doc2、doc3，内容如下。

Suppose the database named my_database that is stored locally in PouchDB contains 3 documents namely doc1, doc2, doc3 with the following contents.

doc1 = {_id: '001', name: 'Ram', age: 23, Designation: 'Programmer'}
doc2 = {_id: '002', name: 'Robert', age: 24, Designation: 'Programmer'}
doc3 = {_id: '003', name: 'Rahim', age: 25, Designation: 'Programmer'}

假设我们要将所有 3 个文档中的年龄值增加 2 岁。为此，首先你需要获取 _rev 值。因此，使用以下代码提取这些文档的内容。

Suppose we have to increase the age values in all the 3 documents by 2 years. For this to happen, first you need to get the _rev values. Therefore, fetch the contents of these documents using the following code.

//Requiring the package
var PouchDB = require('PouchDB');

//Creating the database object
var db = new PouchDB('my_database');

//Retrieving all the documents in PouchDB
db.allDocs({include_docs: true},function(err, docs) {
   if (err) {
      return console.log(err);
   } else {
      console.log(docs.rows);
   }
});

将上述代码保存为 bulk_fetch.js 。执行后，上述程序会显示数据库中文档的 _id 和 _rev 值，如下所示。

Save the above code as bulk_fetch.js. On executing, the above program gives you the _id and _rev values of the documents in the database as shown below.

[
   {
      id: '001',
      key: '001',
      value: { rev: '1-1604b0c3ff69dc1e261265fd60808404' }
   },
   {
      id: '002',
      key: '002',
      value: { rev: '1-b5e49db7e984841bf12a13e3ee548125' }
   },
   {
      id: '003',
      key: '003',
      value: { rev: '1-a7b342786ecc707aa91f3b321a177b51' }
   }
]

现在，你可以使用各自的 _id 和 _rev 值更新文档，如下所示。

Now, you can update the documents using their respective _id and _rev values as shown below.

//Requiring the package
var PouchDB = require('PouchDB');

//Creating the database object
var db = new PouchDB('my_databas');

//Preparing the document
docs = [{_id : '001', _rev: '1-1604b0c3ff69dc1e261265fd60808404', age : 25, },
      {_id : '002', _rev: '1-b5e49db7e984841bf12a13e3ee548125', age : 26, },
      {_id : '003', _rev: '1-a7b342786ecc707aa91f3b321a177b51', age : 27 }]

//Updating the documents in bulk
db.bulkDocs(docs, function(err, response) {
   if (err) {
      return console.log(err);
   } else {
      console.log("Documents Updated Successfully");
   }
});

将上述代码保存到名为 Update_All_Document.js 的文件中。打开命令提示符，并使用 node 执行 JavaScript 文件，如下所示。

Save the above code in a file with the name Update_All_Document.js. Open the command prompt and execute the JavaScript file using node as shown below.

C:\PouchDB_Examples >node Update_All_Document.js

这会更新存储在本地名为 my_database 的数据库中存在的所有文档，显示以下消息。

This updates all the documents that exists in the database named my_database which is stored locally, displaying the following message.

Documents Updated Successfully

现在，如果你在回调之前向 allDocs() 函数添加 {include_docs: true} 作为参数执行 bulk_fetch.js 程序，那么你将可以看到已更新的文档值，如下所示。

Now, if you execute the bulk_fetch.js program by adding {include_docs: true} as a parameter to allDocs() function, before the callback, then, you will can see the values of the documents updated, as shown below.

[
   {
      id: '001',
      key: '001',
      value: { rev: '2-77f3a9974dd578d12f3f2a33aae64c8d' },
      doc: {
         age: 25,
         _id: '001',
         _rev: '2-77f3a9974dd578d12f3f2a33aae64c8d'
      }
   },
   {
      id: '002',
      key: '002',
      value: { rev: '2-43966007568ce9567c96422195fcfa0d' },
      doc: {
         age: 26,
         _id: '002',
         _rev: '2-43966007568ce9567c96422195fcfa0d'
      }
   },
   {
      id: '003',
      key: '003',
      value: { rev: '2-6c5349652527f4f39583ff14f23cd677' },
      doc: {
         age: 27,
         _id: '003',
         _rev: '2-6c5349652527f4f39583ff14f23cd677'
      }
   }
]

Updating Batch from a Remote Database

您可以更新以远程方式存储在服务器（CouchDB）中的数据库中的全部文档。

You can update all the documents from the database that is stored remotely on the server (CouchDB).

要执行此操作，您需要传入 CouchDB 中的数据库路径而不是数据库名称，该路径包含要读取的文档。

To do so, instead of a database name, you need to pass the path to the database in CouchDB, which contains the document that is to be read.

Example

假设 CouchDB 服务器中有一个名为 my_database 的数据库。然后，如果您使用 URL http://127.0.0.1:5984/_utils/index.html 验证 CouchDB 中的数据库列表，您将获得以下屏幕截图。

Suppose there is a database named my_database in the CouchDB server. Then, if you verify the list of databases in CouchDB using the URL http://127.0.0.1:5984/_utils/index.html you will get the following screenshot.

假设我们选择名为 my_database 的数据库，你可以观察到它包含 3 个文档，如下所示。

And assume if we select the database named my_database, you can observe that it contains 3 documents as shown in the following screenshot.

现在，使用以下代码获取这些文档的内容。

Now, fetch the contents of these documents using the following code.

//Requiring the package
var PouchDB = require('PouchDB');

//Creating the database object
var db = new PouchDB('http://localhost:5984/my_database');

//Retrieving all the documents in PouchDB
db.allDocs({include_docs: true}, function(err, docs) {
   if (err) {
      return console.log(err);
   } else {
      console.log(docs.rows);
   }
});

将上述代码保存为 remote_bulk_fetch.js 。执行后，上述程序会显示数据库中所有文档的内容，如下所示。

Save the above code as remote_bulk_fetch.js. On executing, the above program gives you the contents of all the documents in the database as shown below.

[
   {
      id: '001',
      key: '001',
      value: { rev: '3-552920d1ca372986fad7b996ce365f5d' },
      doc: {
         _id: '001',
         _rev: '3-552920d1ca372986fad7b996ce365f5d',
         name: 'Raju',
         age: 23,
         designation: 'Designer'
      }
   },
   {
      id: '002',
      key: '002',
      value: { rev: '1-9af15cb11054ebe03a7816bf6c5e4128' },
      doc: {
         _id: '002',
         _rev: '1-9af15cb11054ebe03a7816bf6c5e4128',
         name: 'Robert',
         age: 24,
         Designation: 'Programmer'
      }
   },
   {
      id: '003',
      key: '003',
      value: { rev: '1-3033b5a78e915c52fd37325d42eb3935' },
      doc: {
         _id: '003',
         _rev: '1-3033b5a78e915c52fd37325d42eb3935',
         name: 'Rahim',
         age: 25,
         Designation: 'Programmer'
      }
   }
]

以下是在存储于 CouchDB 服务器的名为 my_database 的数据库中更新所有存在的文档的示例。

Following is an example of updating all the documents that exists in a database named my_database which is stored in the CouchDB server.

//Requiring the package
var PouchDB = require('PouchDB');

//Creating the database object
var db = new PouchDB('http://localhost:5984/my_database');

//Preparing the document
docs = [{_id : '001', _rev: '3-552920d1ca372986fad7b996ce365f5d', age : 24, },
      {_id : '002', _rev: '1-9af15cb11054ebe03a7816bf6c5e4128', age : 26, },
      {_id : '003', _rev: '1-3033b5a78e915c52fd37325d42eb3935', age : 27}]

//Inserting Document
db.bulkDocs(docs, function(err, response) {
   if (err) {
      return console.log(err);
   } else {
      console.log(+"Documents Updated Successfully");
   }
});

将上述代码保存到名为 Remote_Update_Document.js 的文件中。打开命令提示符，并使用 node 执行 JavaScript 文件，如下所示。

Save the above code in a file with the name Remote_Update_Document.js. Open the command prompt and execute the JavaScript file using node as shown below.

C:\PouchDB_Examples >node Remote_Update_Document.js

这会更新存储在 CouchDB 中存在于名为 my_database 的数据库中的所有给定文档的内容，并显示以下消息。

This updates the contents of all given document that exists in the database named my_database which is stored in CouchDB, and displays the following message.

Documents Updated Successfully

现在，如果你执行 remote_bulk_fetch.js 程序，你将可以看到已更新的文档值，如下所示。

Now, if you execute the remote_bulk_fetch.js program you will can see the values of the documents updated, as shown below.

[
   {
      id: '001',
      key: '001',
      value: { rev: '4-6bc8d9c7a60fed2ed1667ec0740c1f39' },
      doc: {
         _id: '001',
         _rev: '4-6bc8d9c7a60fed2ed1667ec0740c1f39',
         age: 25
      }
   },
   {
      id: '002',
      key: '002',
      value: { rev: '2-1aa24ce77d96bb9d2a0675cdf1e113e0' },
      doc: {
         _id: '002',
         _rev: '2-1aa24ce77d96bb9d2a0675cdf1e113e0',
         age: 26
      }
   },
   {
      id: '003',
      key: '003',
      value: { rev: '2-fa113149ba618eda77f73072974a2bc1' },
      doc: {
         _id: '003',
         _rev: '2-fa113149ba618eda77f73072974a2bc1',
         age: 27
      }
   }
]