Update of MongoDB document (php code example)

MongoDB update documents are divided into two categories:

• Document replacement, completely replace the old document with the new document

• Modifier, Modify some documents

Document replacement

Using document replacement is very simple, let’s take a look at the demonstration:

$collect->insertOne(['name' => 'lakers', 'nums'=> 16]);
$collect->replaceOne(
    ['name'=>'lakers'], 
    ['name' => 'heat', 'nums'=>3]
);

Use modifiers to complete more complex update operations, such as modifying, adding, or deleting keys.

"$set" modifier

"$set" is used to specify the value of a field. If this field does not exist, create it.

$collect->insertOne([
    'name' => 'james',
    'age' => 35,
]);

$collect->updateOne(['name'=>'james'],
    ['$set' => ['fruit' => 'apple']]
);
// fruit字段不存在，则会创建该字段

If you don’t like apple now and want to change to strawberry

$collect->updateOne(['name'=>'james'],
    ['$set' => ['fruit' => 'strawberry']]
);

"$set" can also modify the key type.

# 不止喜欢草莓，还喜欢梨子、香蕉。
$collect->updateOne(['name'=>'james'],
    ['$set' =>
        ['fruit' => 
            ['strawberry', 'banana', 'pear'] 
        ]
    ]
);

"$set" can also modify embedded documents

$collect->insertOne([
    'name' => 'james',
    'age' => 35,
    'brothers' => ['name' => 'wade', 'age'=> 38]
]);

$collect->updateOne(['name'=>'james'],
    ['$set' =>
        ['brothers.name' => 'paul']
    ]
);

"$unset"Modifier

Use" The $unset" modifier can delete the specified field

$collect->updateOne(['name'=>'james'],
    ['$unset' =>
        ['brothers' => '']
    ]
);

"$inc" modifier, increase or decrease the value

and "$set" Like the modifier, if the field does not exist, it will be automatically created. Note: This field value can only be numbers.

$collect->updateOne(['name'=>'james'],
    ['$inc' =>
        ['scores' => 61]
    ]
);
## 现有积分61

Now, 10 points have been obtained.

$collect->updateOne(['name'=>'james'],
    ['$inc' =>
        ['scores' => 10]
    ]
);
## 现有积分71

Later, 50 points were used

$collect->updateOne(['name'=>'james'],
     ['$inc' =>['scores' => -50]
 ] ); 
 ## 现有积分21

Array Modifier

MongoDB provides special modifications for arrays method.

"$push" adds elements

"$push" can add elements to the array. If the array does not exist, it will automatically Create an array. There is now a document used to save article data:

$collect->insertOne([
     '_id' => 1,      
     'title'=>'study mongodb',      
     'create_time' => '2020-08-24 12 :31' 
]); 
$push = ['$push' => ['comments' => 'comments1'] ]; 
$collect->updateOne(['_id' => 1 ], $push);

"$each" adds multiple elements

'$push' can be an array at once Element, if you want to add multiple elements at once, you need to use '$each' together.

$push = [    
     '$push' => 
         ['comments' => 
             ['$each' => ['comment1', 'comment2', 'comment3']]
         ] 
      ]; 
$collect->updateOne(['_id' => 1 ], $push);

"$slice" retains n elements

'$push' is used together with '$slicet' to retain the latest n elements Data, the value of '$slice' can only be negative integers. For example, I only want to keep the latest 3 comments:

# 目前数据如下
 > db.users.find() 
{ "_id" : 1, "title" : "study mongodb", "create_time" : "2020-08-24 12:31", "comment" : [ "comment1", "comment2", "comment3", "comment4", "comment5", "comment6" ] }

$push = [
     '$push' => [ 
        'comment' => [ 
            '$each' => ['comment7', 'comment8', 'comment9'],                                '$slice' => -3 
        ],
     ], 
]; 
$collect->updateOne(['_id' => 1 ], $push);

# 现数据如下 
db.users.find() 
{ "_id" : 1, "title" : "study mongodb", "create_time" : "2020-08-24 12:31", "comment" : [ "comment7", "comment8", "comment9" ] }

"$sort" sorting

can also be used with '$sort' , keep the 3 comments with the most likes.

# 目前是集合内是空的，么有任何文档
$collect->insertOne(['_id' => 1, 'title'=>'study mongodb', 'create_time' => '2020-08-24 12:31']);
$push = [
    '$push' => [
        'comment' => [
            '$each' => [
                ['comment' => 'php', 'like' => 100], 
                ['comment' => 'mysql', 'like' => 10], 
                ['comment' => 'linux', 'like' => 200], 
                ['comment' => 'java', 'like' => 1000], 
                ['comment' => 'nginx', 'like' => 300], 
                ['comment' => 'composer', 'like' => 500], 
            ],
            '$slice' => -3,
            '$sort' => ['like' => 1]
        ],
    ],
];

Let’s take a look at what the data in the collection looks like:

> db.users.find()
{ "_id" : 1, "title" : "study mongodb", "create_time" : "2020-08-24 12:31", "comment" : [ { "comment" : "nginx", "like" : 300 }, { "comment" : "composer", "like" : 500 }, { "comment" : "java", "like" : 1000 } ] }

Note that you cannot only use "$slice" or "$sort" with "$push", and you must Use "$each".

"$addToSet" avoids inserting duplicate data

When using "$addToSet" to add new array elements, you can avoid adding duplicates Data, such as

$collect->insertOne([
    '_id' => 1,
    'name' => 'gwx', 
    'age' => 30, 
    'fruits' => ['apple', 'pear']
]);

$update = [
    '$addToSet' => [
        'fruits' => 'apple'
    ]
];

, the above modification will not succeed because apple already exists. '$addToSet' can also be used with "$each" to insert multiple array elements.

$update = [
    '$addToSet' => [
        'fruits' => [
            '$each' => ['apple', 'banana', 'orange']
        ]
    ]
];
$collect->updateOne(['_id' => 1], $update);

Delete elements

You can delete the leftmost or rightmost element through "$pop".

$collect->insertOne([
    '_id' => 1,
    'name' => 'gwx', 
    'age' => 30, 
    'fruits' => ['apple', 'pear']
]);

#从数组末删除1个元素
$update = [
    '$pop' => [
        'fruits' => 1
    ]
];
$collect->updateOne(['_id' => 1], $update);

# 从数组头删除一个元素
$update = [
    '$pop' => [
        'fruits' => -1
    ]
];
$collect->updateOne(['_id' => 1], $update);

You can also delete the specified element through '$pull'

$collect->insertOne([
    '_id' => 1,
    'name' => 'gwx', 
    'age' => 30, 
    'fruits' => ['apple', 'pear', 'apple', 'banana', 'orange']
]);

#从数组末删除
$update = [
    '$pull' => [
        'fruits' => 'apple'
    ]
];

All apple elements in the array have been deleted

upsert

upsert is a special kind of update. But if a set that meets the conditions is found, it will be the same as the previous modification. If a collection that meets the conditions is not found, it will be inserted into the collection as a new document using the query conditions and the modified document.

Below, take a scenario we often encounter as an example - recording the number of times each IP is viewed. If it is a new IP, it is added to the collection. If it already exists, the original collection is modified.

$collect->updateOne(['ip' => '116.31.23.1'], [
    '$inc' =>[
        'views' => 1
    ]
], ['upsert' => true]);

$collect->updateOne(['ip' => '127.0.0.1'], [
    '$inc' =>[
        'views' => 1
    ]
], ['upsert' => true]);


$collect->updateOne(['ip' => '116.31.23.1'], [
    '$inc' =>[
        'views' => 1
    ]
], ['upsert' => true]);

> db.users.find()
{ "_id" : ObjectId("5f4336f3a95f1a505db9a2df"), "ip" : "116.31.23.1", "views" : 2 }
{ "_id" : ObjectId("5f4336f3a95f1a505db9a2e1"), "ip" : "127.0.0.1", "views" : 1 }

Update multiple documents

Updating multiple documents requires the use of the updateMany() method, as demonstrated below:

$collect->insertMany([
    ['name' => 'gwx', 'age' => 30],
    ['name' => 'gwx', 'age' => 30],
    ['name' => 'gwx', 'age' => 30],
]);

$collect->updateMany([
    'name' => 'gwx'
],
    ['$set' =>['age' => 18]]
);

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