Database Relationships | One To Many & Many to Many | Django (3.0) Crash Course Tutorials (pt 6)

Check out my Complete Django course! dub.sh/NvGboTI
Introduction to Database model relationships. In this video we will be covering "One to Many" and "Many to Many" relationships and how this is implemented in Django.
Follow me on Twitter: / dennisivy11
Linkedin: / dennis-ivanov
Source code: github.com/div...

[@DennisIvy]

Don't forget to check out my Complete Django course! dub.sh/NvGboTI

[@AndreaManna85]

I'm italian and i already watch 2 courses in italian language. But just now with your course i start understand better django! You're really the best... thanks for all!

[@apingsample4720]

Your Visual representation of the relationship help us understand clearly, how i wish there are somethings like this in the Django documentation, it make things very easy! Thanks Dennis!

[@ronanamelin]

The principle was explained much better then most tutorials that are floating around. It`s structured and reproducible. +1 to your channel! Cheers!

[@DennisIvy]

I appreciate that Georgi :)

[@parthjani8301]

excellent explanations, keep uploading, love from India

[@nurbektaizhanov4534]

+

[@rafatulalam8677]

Really good content Dennis. Can you make a future mini series on understanding model relationships in Django and at the same time explaining the concept of making good ER diagrams for any website project. There are not many videos out there covering these concepts in depth and you explain extremely well. It would be really helpful if you would consider making a series like that in the near future

[@afelixalves]

I'm half way, but just need to say that this tutorial is way to great to be free... Premium content, without question!

[@theanonymous92]

Great Video Thnx a lot for those who are super confused in the relations and then the code for relationships; I recommend watching this video again(and again) till your minds actually recognizes the pattern( you may take a break if you don't get it) BEST OF LUCK

[@abdifatahwebdeveloper117]

I took many tutorials before this tutorial I have never seen like this one thanks million times dennis ivy

[@gersoninthekitchen6656]

Thanks Dennis, you saved me £30,000 from University. I really appreciated.

[@grandorigins6682]

Dennis, you make the best videos on Django. I am an engineer from South Africa. You are the most relatable coding youtuber to me. Keep making great content. It helps more than you know!!!

[@yogeshyts]

manytomany field is used when we need to connect an object with many objects of another table, Product can have multiple Tag like ice cream is product and summer,food are Tags.

[@stevesamah4018]

This is super helpful I'm going to subscribe just because of this video.

[@DennisIvy]

So glad you found it helpful! I didn’t know if the drawings would make it more confusing but they seem to be helping :)

[@akash4952]

@@DennisIvy drawing did help us infact i understood that before building a long project, make a diagram .Thank you loving the course:-)

[@akashpushkar306]

@@DennisIvy First of all, thanks for such amazing lectures you are taking. How can I load data in my UI and apply slicers/filters on the data from .csv files in the dashboard. Secondly, how can I take user input on the dashboard and run an ML model in the background and refresh the dashboard. Any link for tutorials would be really great.

[@wethepeopleofghana8441]

This guy is now my go-to expect on most topics in Django. Dennis Ivy += 1 sub.

[@mimishiba]

I did relational database for quite some time. Glad you corrected that Tags should be on Product and not on Order. It bothered me but I kept watching anyway cos I'm clueless with Django. Great series!

[@jaumemontane3305]

I finished an entire udemy course and made two project tutorials on it but I didn't understand this concept until this video and project. Thanks mate!

[@adbeelomiunu]

For whoever is following along with this video: Just in case you get stuck at the point where you can see the Tag section on the site go to admin.py file in your IDE and add it there so that it registers on the site just like he added those of Customer, Product and Order sections in the previous video on this playlist.

[@ursoothesoul7705]

Was just looking for this thanks pal

[@danielkemmet2594]

Hey Dude, Thanks for the video. Its helping me spin my own Ticketing System with DRF and PSU! 20$/mo back into my business's pocket!

[@rboi]

i never really understood the intermediary table in the ManyToMany relationship until now, Thanks a lot for giving such a clear and easy to understand explanation!

[@snowsenpai_]

Best Django series I have ever seen 😍🔥super easy to understand💯

[@rickykuo8360]

many thanks to Dennis!! this channel is really beginner friendly

[@chaitanyasai2458]

Hi Dennis, I love your way of Explanation. could you please also do a video about how to add foreignkey relationship in modelforms and render both in single template? Where foreignkey value can be choosen automatically while filling the form

[@AviralJain]

Excellent Explanations ! The first thing I do before watching your video is to like it ❤

[@DennisIvy]

Haha really appreciate the support! Glad these videos are so helpful :)

[@vaishnavi4354]

It's just awesome... I referred a lot videos for django. .but your series is awesome..no comparison 🙇🙇🙇🙇

[@STU0408]

Thanks for the video. Very helpful! Does anybody know why the multiselect option is provided only on one side of the model in the admin panel if Many-To-Many is used? Theoretically it should be shown on both sides.

[@i701Dev]

Can you do a follow up tutorial to this video explaining how to create a Model Form from the Order model?

[@alcaravan555]

Suggestion: press F7 and DOS window will display all the commands you entered previously

[@achrafelkhanjari9157]

From Morocco cheers mate.

[@raresduta1508]

Thanks! Your free explanations are the best. Keep it like this

[@murtazaahmad9559]

You are the best Teacher. Thanks for creating such videos.

[@nomeshkumar6603]

Hey I understand the concept of many to many and one to many, the way you implement it I also do the same but I am unable to understand how many to many relationship data will we stored because we have not created any intermediate table and also I am unable to find it in my database.

[@Adarsh8750]

You've put in lot of hard work on this Appreciation from India

[@rayganmudberry375]

please keep uploading awesome videos with great concept. thank you

[@elmurodtadjibayev3212]

Greatest videos about Django I've ever seen. Super Dennis.

[@6ftofmisery636]

Hey Dennis, I understand the logic behind one to many relationship for the customer but what if we have a large number of customers? don't you think a drop down feature would be slightly awkward?

[@RaefetOuafiqo]

that's just the default representations from admin-django if u want to search and get more out of field I thnk using the database in more helpful

[@prasannadeshpande4435]

Very good tutorial. Certainly deserves more subscribers and likes.

[@omkarpatil4386]

i didn't get why you write pending two times and out for delivery two times in tuple and thanks for your videos.

[@rangabharath4253]

One is for key another is for value. Try it once changing the names of values

[@michealwaldrup4357]

Explained differently. ('db_value', 'DB Value') The first is the actual value that will be entered in the DB (ie. 'db_value'). The second is the text representation of that value that will be shown in Django generated form inputs (ie. A select box with 'DB Value' as an option, when chosen will enter db_value into the database for that column.

[@jhoniemusic]

soooo good.... nice. so if the Customer just cancel a ORDER that he or she made. the Order still on are database, as a Canceled ordered status, right??? sorry for my ENGLISH. but great Job.

[@alexissuarezalvarez5622]

Hello, I am not entirely clear why an order must be one to many with customer. a specific order is made by a customer.

[@scottrowson]

Instead of have choices via a dropdown, is it possible to have checkboxes and allow multiple options to be chosen?

[@ahmadjuuko352]

Very impressive explanation. But why don't you use cascade on delete so that the order made by a certain customer is also deleted when he is deleted to avoid orphaned entries

[@mouadkerdoud9428]

I don't get why products and orders don't have a ManyToMany relationship. A product could be in a relationship with many orders (as in, was ordered multiples times), on the other hand, an Order could have multiple products in it, and so multiple relationships ?

[@vinnbrock]

Denis Ivy , at 11:06, you mention changing the tags selection to a multi-select checkbox. I can't find where you do that in this video, or the next. Where/how do you change that? Also how could I change a dropdown option to radio buttons. BTW, thank you for awesome content!

[@deepanshuyadavcs1379]

I really appriciate your content. I have been stuck in this for a long time. Thanks Again✌️

[@mikef6785]

Dennis at 11:11 you mention that you would be change the ManyToManyField to a checkbox in the admin. Did you ever get to that?

[@LetCode96666]

Some tutorials are goo, some are so good and well explained which is also easy to follow and then comes your videos! Perfect tutorials to learn from! Thanks a lot

[@Alkik0]

Loud and clear, thanks mate !

[@birukbringland4030]

five times i saw it is awesome

[@JEBJOSH]

really helpful. The diagrams u draw and how you explain are rally helpful. thank you

[@DennisIvy]

I'm really glad those helped! I thought it might be distracting putting them in there so I'm glad they are working :)

[@matthieuo39]

Everything in this tutorial is awesome ! Your explanations are very good too. Thank you

[@ivofrancisco357]

Great explanations man. I've seen your in CodingPhase but never visited your channel. Now I'm a subscriber eheh.

[@aidanali9483]

Thanks! Hello from Kazakhstan!

[@glennpotter4079]

Wow, great teacher!

[@VijayKumar-dq3ph]

Hi , do you have video explaining foreign key relations among tables of different databases or any hint on how to achieve that?

[@k.m.jiaulislamjibon1443]

@Dennis Ivy.... Thanks for your journey of videos . It helping a lot. One more thing here you are adding selecting the Customer manually cause you are admin. But suppose when a customer orders a thing then in the order form can you plz show me way to select the user automatically to "Current User" where i have choices of users. thanks

[@rayganmudberry375]

Please upload one video daily. spread the knowledge. thank you

[@DennisIvy]

Uploading two right now :) had to reshoot yesterday’s because I didn’t like the way it turned out.

[@rayganmudberry375]

@@DennisIvy thank you.

[@TheShadyStudios]

You're a great teacher bro

[@malharyadav3357]

I love this playlist and you really great at explaining the basics too! I had one question how does Django only ask for customer name specifically in order model like it access name column only what if we want to access another column from customer in order model?

[@isaactonyloi2185]

Thank you Denis God bless you

[@mrvalvet9856]

Dennis, thank you for this useful tutorial! Easy to follow, well done!

[@fowad27]

I'm confused as to why you had to run migrate at 8:44 but not at 12:11, even though you made a change to the models.py file?

[@svetliodoychinov5580]

Great video coming from FastAPI where you need to be doing more sql than python sometimes I am very surprised how simple the relations are in Django. It’s really cool.

[@jorgeandrescruces7058]

Thanks for this content man. The quality is awesome

[@akashpushkar306]

@Dennis Ivy: First of all, thanks for such amazing lectures you are taking. How can I load data in my UI and apply slicers/filters on the data from .csv files in the dashboard. Secondly, how can I take user input on the dashboard and run an ML model in the background and refresh the dashboard. Any link for tutorials would be really great.

[@benjaminmensah5110]

I just watched this and am amazed. Thanks

[@rockeraman15]

Thanks a ton man, you made it so simple to understand

[@abdurahmanyusuf5170]

keep going amazing video sir thanks alot from somalia

[@TheEaglesBasket]

If you delete a product, it will be null in the order. So it will be impossible to have a order history for a customer. And if you change a price of a product, then the order would not show the price when ordering. There must be a better way to do this?

[@danielvaliente007]

Good morning , please is it possible to implement this many to many relationship and one to many relationship using mysql as my database

[@davidbrown2806]

1. Why are the date_created fields not showing up in the Admin ? 2. Would be nice to have sqlite3 create Order Numbers sequentially automatically, and display.

[@abinanto6394]

what if there are 1000 customers and we need to add an order . how to select the customer

[@ashrafulfuad2967]

thank you sir really great explanation with good example

[@johnsonvaughn2366]

How should I make more user friendly to many to many field in admin panel? TabularInline is not good when too many values in many to many field.What should I use?

[@tehreemakhtar8652]

Don't you think that relationship between Orders and Products should be many to many because normally one order can contain multiple products. I'm a lil confused just because of this.

[@felreizmeshinca7459]

@12:15 Wait a minute, we don't have to makemigrations & migrate after changing the codes in models.py?

[@rssvprasad9859]

why to create a new customer user name and email? how can I directly import already existing users from table and display on page model customers!

[@khatibmahmud263]

Boss of the Bosses

[@tahmidbaquee1740]

Hello Dennis, I understand the logic of the relationship between custormer and order(one to many) but I am confused about the relationship between product and order. Is it because a single product can have multiple orders in which case product will be the parent and orders will be children? By the way keep up the good work. Really enjoying your series.

[@DennisIvy]

Yes that's correct. A product is a type of item a store caries. But an order is just an instance of that product. Lets say a store holds the product of a "Bike". We need multiple customers to be able to Order a bike. So we can identify which product the customer ordered by looking at its parent.

[@shagunmathur7611]

@@DennisIvy What if there are multiple Products in a particular Order. Do we have to create many to many relationship between Order and Product Models?

[@4MXW]

@@shagunmathur7611 I think YES (by the way he selects multiple tags and it is also a ManyToManyField)

[@fatmafilali3429]

Whenever I try to add a foreign key, it displays this error: 'Cannot add or update a child row: a foreign key constraint fails.Can you please help me?

[@rdarktemplar1989]

i believe its missing a video about how to handle errors when trying to delete data from the web application instead of the given example from console and django admin

[@trungle6039]

Hello Dennis, In fact, on each order buỷer can buy some products.so I used: product = models.ManyToManyField(Product). is it Ok ?

[@julianamaya974]

I think the same. An order could have many products.

[@hamza-325]

It can be like that, but it is mandatory in Relational DBMS (database management systems) to simplify all many-to-many relations to one-to-many. However, Django seems to like simplifying things too much and not requiring this.

[@brhh]

what if the customer was A user in the project's database?

[@aavlasti]

The course is really great, but I have a question. Why we put the Tags class above the Product class? We can not just write it anywhere and access it? I mean why we need to have the order(not the Order class) in the code file? Is it just a preference from you? or it will not work otherwise?

[@Magistrado1914]

Excellent course 11/07/2020

[@SunPhanithVataNakE]

So How can we get data from Tage table ? like to display in home page

[@ThePrashantsonu]

how to override from multi select option to multi checkbox

[@devngecu]

This may not be quite clear but i hope you understand: I have created my class models with the relationships addressed in this video.But every class requires the foreign key class to be predefined above it,making the whole process an infinite loop.How do i tackle this?

[@user-ds6to3ly8i]

I have one question following the link between Product and Order : Why don't we use ManyToManyField instead of One To many ? because in one order we can have many products and one product can appear in many orders .

[@israelsamson5846]

the logic is in order to order many products customer needs to order again and again b/c customer had 1 to many rln with the order so idealy there is a many to many rln between the customer and product

[@diwasbasyal9882]

@Dennis why i get error while opening source code ..error like this Application error An error occurred in the application and your page could not be served. If you are the application owner, check your logs for details. You can do this from the Heroku CLI with the command heroku logs --tail

[@Modafinil]

I tried to form a primary key that would contain two fields. If I understood right the info I found from web, Django does not support such feature and it has been so for a long time. What could be so difficult/overwhelming to prevent to implement a common feature like that?

[@CircuitNotion]

very helpful bro!

[@ursoothesoul7705]

I'm getting an issue while adding data to order when i choose customer name it says Order object has no attribute name Seems like the foreign key is noy connecting anyone can help?

[@wong1139]

感谢您的教程，对我的学习很有帮助！

[@juanignaciodominguez5902]

Great explanation! Thank you!

[@bishaladhikari8691]

why product and order have one to many relationship ?

[@gowthamns8228]

Can you please explain how to join tables (inner join) the joining tables has no foreign key relationships in django orm and once join is happen how to serialize the data to create API?

[@1a9Cj5]

Thanks for the excellent content. Though on 2:00 I think one product (ball) can have both Sports Tag and Summer Tag but then BBQ Grill can't have summer as a tag. It is one to many not one to one. Am I right?

[@rangabharath4253]

Awesome as always bro

[@evankadsouza8058]

i had a doubt. can the orders be entered via the form given to the user too? instead of manually entering them in the db

[@dislikebutton3509]

13:36 how can we change order name from 'Order object'

[@AFuller2020]

When did you load the models.py? Not in this course, should we imported into this course from another?