mongodb 脚本

https://docs.mongodb.com/manual/tutorial/write-scripts-for-the-mongo-shell/

Shell Helpers	JavaScript Equivalents
show dbs, show databases	db.adminCommand('listDatabases')
use <db>	db = db.getSiblingDB('<db>')
show collections	db.getCollectionNames()
show users	db.getUsers()
show roles	db.getRoles({showBuiltinRoles: true})
show log <logname>	db.adminCommand({ 'getLog' : '<logname>' })
show logs	db.adminCommand({ 'getLog' : '*' })
it	cursor = db.collection.find() if ( cursor.hasNext() ){ cursor.next(); }

EXAMPLE

To print all items in a result cursor in mongo shell scripts, use the following idiom:

cursor = db.collection.find();
while ( cursor.hasNext() ) {
   printjson( cursor.next() );
}

forEach：

db.collection.find().forEach(<function>)

db.restaurants.find().forEach( function(myDoc) { print( "name: " + myDoc.name ); } );

 执行脚本的3中方法

1.  --eval

mongo test --eval "printjson(db.getCollectionNames())"

2.Execute a JavaScript file

mongo localhost:27017/test myjsfile.js

3. load：You can execute a .js file from within the mongo shell, using the load() function

load("myjstest.js")

练习：

批量删除receive库中所有collection 的数据

my.js

db = db.getSiblingDB('receive')
c = db.getCollectionNames();
c.forEach(function(value, index, array){
    print(value);
  db.getCollection(value).remove({});
})

在mongo 的shell中执行load('path/my.js')