Mongodb University Courses Note
Mongodb University的M101P: MongoDB for Developers与M102: MongoDB for DBAs课程第二周笔记
官方文档地址
api文档
CRUD
Create
db.collection.insertOne()
db.collection.insertMany([ {...},{...} ], {"ordered":false}) # 详细参数见文档，第二个参数可省。Excluding Write Concern errors, ordered operations stop after an error, while unordered operations continue to process any remaining write operations in the queue.
Retrieve
db.collection.find({"actors":"Mark Fergus"}) # 查找的结果中actors字段可以为列表，只要包含Mark Fergus即可( Match any element of an array)
db.collection.find({"actors.0":"Mark Fergus"}) # match the first element of an array
db.collection.find( {"actors":["Mark Fergus", "Jeff Bridges"]} ) # 查找的结果中actors字段必须包含Mark和Jeff，并且Mark在Jeff前。
cursors
游标batch中剩余的文档数
cur.objsLeftInBatch()
projection
只返回需要的字段，Week1已讲，db.collection.find() 的第二个参数实现。
db.movies.find({}, {field1:1,_id:0})
Operators
Comparison Operators
$eq, $gt, $gte, $lt, $lte, $ne, $in, $nin
db.collection.find({"field":{"$lt":100,"$gt":60}})
Element Operators
$exists, $type
db.collection.find({"tomato.meter":{"$exists":true}})
Logical Operators
$or, $and 当查询条件中多次涉及同一字段时用$and，如 {$and:[{$grade:{$exists:true}}, {$grade:{$ne:null}}]}
db.collection.find({$or: [{$field1:val1}, {field2:val2}] })
db.collection.find({$and: [{$field1:val1}, {field1:val2}] })
Regex Operator
$regex
db.collection.find({"strfield":{$regex:"pattern"}})
Array Operators
$all, $size, $elementMatch
db.collection.find({actors:{$all:["actor1", "actor2", "actor3"]}})
db.collection.find({actors:{$size:1}})
boxOffice: [ { "country": "USA", "revenue": 41.3 },
{ "country": "Australia", "revenue": 2.9 },
{ "country": "UK", "revenue": 10.1 },
{ "country": "Germany", "revenue": 4.3 },
{ "country": "France", "revenue": 3.5 } ]
db.collection.find({ boxOffice: { country: "UK", revenue: { $gt: 15 } } })
# 会匹配以上字段，country和revenue不被限制在同一元素内
db.collection.find({ boxOffice: {$elemMatch: { country: "UK", revenue: { $gt: 15 } } } })
# country和revenue被限制在同一元素内，匹配失败
Update
UpdateOne
Update Operators: $inc, $mul, $rename, $setOnInsert, $set, $unset, $min, $max, $currentDate
db.movieDetails.updateOne({title: "The Martian"},
{ $set: { "awards" : {"wins" : 8,
"nominations" : 14,
"text" : "Nominated for 3 Golden Globes. Another 8 wins & 14 nominations." } } });
Array Update
Array Update Operators: $addToSet, $pop, $pull, $pullAll, $push, $pushAll
db.movieDetails.updateOne({title: "The Martian"},
{$push: { reviews:
{ $each: [
{ rating: 0.5,
date: ISODate("2016-01-12T07:00:00Z"),
reviewer: "Yabo A.",
text: "i believe its ranked high due to its slogan 'Bring him Home' there is nothing in the movie, nothing at all ! Story telling for fiction story !"},
{ rating: 5,
date: ISODate("2016-01-12T09:00:00Z"),
reviewer: "Kristina Z.",
text: "This is a masterpiece. The ending is quite different from the book - the movie provides a resolution whilst a book doesn't."}],
$position: 0,
$slice: 5
}
}
})
$each 用于将列表中的文档作为单独的元素逐一插入，否则整个列表作为一个列表元素插入, $position:0 用于插入到列表前，$slice用于限定列表长度，详见文档
UpdateMany
db.movieDetails.updateMany( { rated: null },
{ $unset: { rated: "" } } )
Upsert
要更新的文档不存在时插入创建新的文档
db.movieDetails.updateOne(
{"imdb.id": detail.imdb.id},
{$set: detail},
{upsert: true});
replaceOne
_id字段不变替换文档内容
db.movies.replaceOne(
{"imdb": detail.imdb.id},
detail);
Pymongo
find_one, find, cursor, insert_one
find_one直接返回一个结果，find函数返回游标，游标可迭代。query与projection与mongo shell中语法一样，但python要求key加引号。
import pymongo
connection = pymongo.MongoClient('mongodb://localhost')
db = connection.db_name
collection = db.collection_name
doc = collection.find_one(query, projection)
cursor = collection.find(query, projection)
collection.insert_one(new_doc)
Sort, Skip and Limit
获取的查询结果总是按照sort, skip, limit的顺序进行，无论其在python中的调用顺序，因为只有在从cursor中读取结果集的时候才真正进行数据查询。
pymongo的排序语法与mongo shell差别较大，因为mongo shell中的json保持了key的顺序，而python的字典则是无序的，所以采用列表。
cursor.Skip(3)
cursor.limit(5)
cursor.sort([("field", pymongo.ASCENDING), ("field2", pymongo.DESCENDING)])
insert_one
当未提供_id字段时插入，可能会出现重复数据。当提供_id字段时，如果数据库中已有_id值相同的文档则插入失败。
richard = {"name": "Richard Kreuter", "company": "MongoDB",
"interests": ['horses', 'skydiving', 'fencing']}
andrew = {"_id": "erlichson", "name": "Andrew Erlichson",
"company": "MongoDB", "interests": ['running', 'cycling',
'photography']}
people.insert_one(richard)
people.insert_one(andrew)
# Insert again
people.insert_one(richard) # succeed
people.insert_one(andrew) # fail
insert_many
ordered设为False时，某个文档插入失败不会影响后续文档插入。
insert_many(doc_list, ordered=True)
Update Data
与mongo shell语法相似。
update_one(filter, update_statement, upsert=False)
update_many(filter, update_statement, upsert=False)
replace_one
replace_one实际调用了update方法，在获取文档再替代的时间内原文档可能已被修改。
replace_one(filter, new_doc)
upsert
update和replace的upsert结果不同，下面例子中，update insert后插入的文档包含thing字段，而replace upsert后插入的文档不包含thing字段。
update_one({"thing":"banana"},{"$set":{"color":"yellow"}},upsert=True)
update_many({"thing":"banana"},{"$set":{"color":"yellow"}},upsert=True)
replace_one({"thing":"banana"},{"$set":{"color":"yellow"}},upsert=True)
delete_one, delete_many
没啥特殊的，就给个filter参数删除。。。
find_and_modify
find_one_and_delete/replace/update()
参数有 filter, update, projection, sort, upsert, return_document, **kwargs
return_document 默认为BEFORE，即返回修改前的文档。
db.test.find_one_and_update(
{'done': True},
{'$set': {'final': True}},
sort=[('_id', pymongo.DESCENDING)])
db.example.find_one_and_update(
{'_id': 'userid'},
{'$inc': {'seq': 1}},
projection={'seq': True, '_id': False},
upsert=True,
return_document=pymongo.ReturnDocument.AFTER)
