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One , Preface

Next chapter . Mentioned in the previous article ：
Today, there is another small demand ： as follows ： The ranking list can view the class ranking .
Problems to be solved ：
1, Class attributes need to be added when registering .
2, The database needs a small change .
3, For the sake of friendliness , I added a segment display in the personal championship . Very friendly .
4, Add class ranking to the ranking list .

And I wrote the first three requirements , Write down the fourth requirement today .

Two , Back end —— Class ranking

First , Define a sum Variable , Inside mongo All data of table .

list_clss=[]
sum = db.mongo.find()

Define an empty list_clss list .
Purpose ： Let's traverse the class value .

 for i in sum:
        sum_fries.append(i)
        if(i['class'] not in list_clss):
            list_clss.append(i['class'])

The above code block is explained as follows ：
Let's loop through sum.
then sum_fries Is another storage sum Table content （ It's equivalent to making a copy of ）.
Add a traversal storage condition . If , Now traverse to the value . stay list_clss If it is not in the list, add it , If . Some words , No additional .
Realization function ：
De duplication function , Extract the registered user class now , Convenient follow-up operation .

list_clss_sum=[]
    list_clss_people=[]

The above code block is explained as follows ： Define two empty lists .
One is to put the total class points , The other is to put the number of classes , The listed method stores .

The above code block is explained as follows ： Get list length , loop , Accumulate the current points of the people in the target class , Store in the corresponding sum In the list .
The number of people is the same , Every time you find a target , Self increase one .
str(list_clss[j])==str(ii[‘class’]), This is the screening criteria .

for jj in range(0,len(list_clss)):

The following is all right mongodb Data operation problems , as follows ：

Get our dictionary set ready .

if(find==None):
    db.classdb.insert_one(classdb)
if(find!=None and find_again==None):
    db.classdb.update_one(
        class_find,
        {
    '$set':class_again
         }
    )

The above code block is explained as follows ：
Situation 1 ： If you don't find the current content in the class data , Do the add operation , The code above find==none.
Situation two ： If the goal is already in the class database , But it's not exactly the same , We need to perform the update mongodb Operation of database .

after_find=db.classdb.find({
    }).sort([("average", -1)])

Last , Code above , We use mongodb Sorting function of , Has been evenly divided into goals , Sort in descending order .

append=[]
    for i in after_find:
        append.append(i)
    print(append)

Then write a traversal , Put the sorted database target value , Add one by one to append in . Then pass it to the front end , Realize the functional requirements of class ranking .

3、 ... and , Results display

Last .MUI Zhenwen ！