Parfait18/django-app

django-app

SImple django application

MongoDb guidance

Summary of command mongo database in order to interact with database

Create database

use database

Create collection

db.createCollection('collectionName')

Insert in collection

insert one line

db.collectionName.insertOne({
    field: "value",(string value)
    field: value,(integer value)
    field: ["news", "events"],(array value
    field: Date() (date value)
    field: {
        field: value,
        field: value
    }( dic value)
})

insert many line


db.collectionName.insertMany(
    {
    field: "value",(string value)
    field: value,(integer value)
    field: ["news", "events"],(array value
    field: Date() (date value)
    field: {
        field: value,
        field: value
    }( dic value)
},{
    field: "value",(string value)
    field: value,(integer value)
    field: ["news", "events"],(array value
    field: Date() (date value)
    field: {
        field: value,
        field: value
    }( dic value)
},{
    field: "value",(string value)
    field: value,(integer value)
    field: ["news", "events"],(array value
    field: Date() (date value)
    field: {
        field: value,
        field: value
    }( dic value)
}
)

Find data in collection

find all data which match with my condition

db.collectionName.find({
    category : 'value'
})

find all data which match with my condition and display the title and date fields in the results

db.collection.find({
    {(for condition)},
    { data:1, title: 1, _id:0}

})

We use a 1 to include a field and 0 to exclude a field.

find one element db.collectionName.findOne()

Update collection

update collection which match with condition

db.collectionName.updateOne(
    {title : "value"(condition)},
    { $set: {field: "value"} }(update))

insert new data if not found

db.collectionName.updateOne(
    {title : "value"(condition)},
    { $set: {field: "value"} },(update)
    {upsert: true}
    )

update all data in collection who match with condition

db.collectionName.updateMany(
    { title : "value"(condition),
    { $inc: { field: value}}}
)

Delete data from collection

delete first element which match with condition

db.collectionName.deleteOne(
    {title : "value"(condition)},
    )

delete all elements of collection which match with collection

db.collectionName.deleteMany(
    {title : "value"(condition)},
    )

Query operator

Comparaison

$eq : value are equal
$ne : value are not equal
$gt : value is greater than another
$gte : value is greater or equal than another
$lt : value is less than another
$lte : value is less or equal than another
$in : Value is matched within an array

Logical

$and : return documents wher both query match
$or : return documents where one of both query match
$nor: return documents where both query fail to match
$not : return documents where query does not match

Evaluation

$regex : allow use of regular expressions for field evalutation

Aggrégation Pipeline

Aggregation operations allow you to group, sort, perform calculations, analyze data, and much more.

Aggregation pipelines can have one or more "stages". The order of these stages are important. Each stage acts upon the results of the previous stage.

aggregation example of use

db.collectionName.aggregate(
    [
        // Stage 1: Only find documents that match condition  
        {
           $match: {field : { $gt: 1}} (condition example)
        }  ,
       // Stage 2: Group documents by category and sum each categories likes (exmaple)
       {
       $group : {
           _id: "$category", 
           totalLikes:{ $sum : "$likes" }
            }
       }
    ]
)

$group

This aggregation stage groups documents by the unique _id expression provided.

db.collectionName.aggregate([
    {
        $group: { _id: "field_want_to_group_by_name"}
    }
])

$limit

This aggregation stage limits the number of documents passed to the next stage.

db.collectionName.aggregate([
    { $limit: 1}
])

$project

This aggregation stage passes only the specified fields along to the next aggregation stage.

db.collectionName.aggregate([
  {
    //display only name, cuisine and address field
    $project: {
      "name": 1,
      "cuisine": 1,
      "address": 1
      "_id": 0 // exclud _id field
    }
  },
  //limit resutl for 5 element
  {
    $limit: 5
  }
])

$sort

This aggregation stage groups sorts all documents in the specified sort or

db.collectionName.aggregate(
    [
        { $sort: { "field_want_to_sort": 1 }}
    ]
)

The sort order can be chosen by using 1 or -1. 1 is ascending and -1 is descending.

$match

db.collectionName.aggregate([
    { $match: { field: "value"}}
])

$addFields

This aggregation stage adds new fields to documents.

db.collectionName.aggregate([
    { 
        addFields: {
            avgScore: { $avg: "$grades.score"}
        }
    }
])

$count

This aggregation stage counts the total amount of documents passed from the previous stage.

db.collectionName.aggregate([
    { $match: { field: "value"}}
    { $count: "totalChiness"}
])

Parfait18 / django-app