Questions & Help>Questions

Self referencing many-to-many

#ecto#many_to_many#self-reference
drakvuf

drakvuf

Self referencing many-to-many

I’d like to create a recommended product feature on an app I’m working on and I’ve found a few articles about this topic but something is messed up and when I try to create a recommended product it only partially works.

In my DB I see that it successfully create a new row but only saves the product_id and the recommended_id is empty.

Here are some snippets of my code which I think is relevant to this topic. Let me know if you need more.

Any idea what might be the problem?

2 comments
#ecto#many_to_many#self-reference
2 814 2

Marked As Solved

kokolegorille

kokolegorille

Try to add join_keys: [product_id: :id, recommended_id: :id], like this

many_to_many :recommended_products, Product, join_through: "recommended_products", join_keys: [product_id: :id, recommended_id: :id], on_replace: :delete
2
Post #2

Where Next?

View thread on forum (has 2 responses!)
ecto
many_to_many
self-reference
Home Questions & Help>Questions
#ecto#many_to_many#self-reference
2 816 2
Last post

Popular in Questions Top

aalberti333
Questions & Help>Questions

Enum.map over list of key/value pairs with a map as the value
As the title describes, I’m trying to run Enum.map() over a list of key/value pairs, where the value is a map. My data looks like this: ...
#enummap
7 19677 6
New
_russellb
Questions & Help>Questions

Web scraping tools
I want to try my hand at web scraping. What tools/libraries do I need to use. I’m hoping to turn this into something professional so don’...
#web-scraping
123 19127 45
New
Trevoke
Questions & Help>Questions

(EXIT) no process: the process is not alive or there's no process currently associated with the given name, possibly because its application isn't started
I have an umbrella app. Some of the apps inside depend on other apps in the umbrella, unsurprisingly. I'm writing a test for one of t...
#otp#umbrella#testing#exunit#errors
26 21431 11
New
lk-geimfari
Questions & Help>Questions

The most correct way to read a JSON file
What is most correct way to open, read and parse JSON file with poison? For example if we have example.json file in root of some projec...
23 13679 2
New
Phillipp
Questions & Help>Questions

Problems with Elixir (erlang crypto module) on Ubuntu (ARM)
Hey, I have a NanoPi-M3 and try to install Elixir on their Ubuntu image. I followed the Raspberry Pi installation instructions from the ...
#linux#troubleshooting
9 14729 20
New
shahryarjb
Questions & Help>Questions

How to convert map to string (separated with ,)
Hello, I have map which I want to convert it to string like this: the map: %{last_name: "tavakkoli", name: "shahryar"} the string I ne...
#maps#strings
15 15491 2
New
WestKeys
Questions & Help>Questions

Mint vs Finch vs Gun vs Tesla vs HTTPoison etc
Currently suffering from paralysis by [HTTP client] analysis. This is rather unusual in Elixirland as there tends to be consensus on the ...
#http_client
252 21859 30
New
sabri
Questions & Help>Questions

Ecto pool_size?
Can someone explain the settings of pool_size of Ecto in config file? and what is the recommend size? Thanks
#ecto
30 14050 5
New
romenigld
Questions & Help>Questions

Docker run Error loading shared library libstdc++.so.6 and libgcc_s.so.1
I am trying to run a deploy with docker and I successfully runned with this command: docker build -t romenigld/blog-prod . but when I t...
/phoenix#deployment#docker-compose
30 19932 15
New
vrod
Questions & Help>Questions

Starship (cross-shell prompt) error - (starship::utils): Executing command "elixir" timed out
I am using the Starship cross-shell prompt – it seems pretty nice, but I get some errors: [WARN] - (starship::utils): Executing command ...
#starship
8 17167 3
New

Other popular topics Top

openscript
Questions & Help>Questions

How to set up the Elixir SDK in Intellij IDEA with the intellij-elixir plugin?
Hello! Sorry for this astonishing simple question, but I’m really stuck. I try to set up the intellij-elixir plugin, but I don’t know ho...
17 22671 9
New
jerry
Questions & Help>Questions

Ecto query using like/ilike in query
Good day to you all. I have been struggling to get a query involving like and ilike to work. Can anyone assist me on this, please? pro...
#ecto
17 16504 10
New
lastday4you
Questions & Help>Questions

How to check Elixir version
I wanted to check elixir version in phoenix because i found that my elixir is 1.5 but when i use Enum.chunk_by it said the function is un...
#how-to-question
11 18647 3
New
danschultzer
Libraries & Projects>Libraries

Pow: Robust, modular, extendable user authentication and management system
None of the current solutions worked well for me, so I went ahead and built a user management system from scratch. This project took far...
/phoenix#authentication#library#authorization#user_system#pow
548 27727 240
New
minhajuddin
Questions & Help>Questions

Using List.first instead of Enum.at(0)
I have seen a lot of code which picks the first element from a list using Enum.at(0) instead of List.first. Is there a reason why people ...
#code-style
76 33273 14
New
chensan
Questions & Help>Questions

(Postgrex.Error) ERROR 42804 (datatype_mismatch): column "" cannot be cast automatically to type integer
I have a User schema with a :from_id field set to type :string: defmodule TweetBot.Repo.Migrations.CreateUsers do use Ecto.Migration ...
#ecto
29 13294 4
New
shahryarjb
Questions & Help>Questions

How to convert map to string (separated with ,)
Hello, I have map which I want to convert it to string like this: the map: %{last_name: "tavakkoli", name: "shahryar"} the string I ne...
#maps#strings
15 15491 2
New
ovidiubadita
Questions & Help>Questions

Elixir for game development
Hey all, I discovered Elixir and I love it. I always wanted to learn a functional programming and I intended to go for Haskell, but afte...
#game
30 23202 25
New
josevalim
Official Elixir>Proposals

Behaviours, defoverridable and implementations
Hi everyone, One of the features added to Elixir early on to help integration with Erlang code was the idea of overridable function defi...
#official-elixir-proposal
111 22687 35
New
lucidguppy
Questions & Help>Questions

How do I read a file and enumerate its lines
I have a super simple question about elixir - how would I take a file like this foo bar baz and output a new file that enumerates th...
#how-to-question
20 15454 3
New
Back to top

Questions & Help>Questions

Questions Questions ❯

Latest on Elixir Forum

Elixir Forum ❯

Sponsor Spotlight

WyewWorks

Enabling companies to succeed by building software people love.

Our Sponsors

Dashbit

Build Elixir applications with speed and confidence.

EEF

Supporting innovation across the BEAM ecosystem.

Coders51

We build reliable cloud platforms for business-critical systems.

AppSignal

Catch errors, track performance, monitor hosts and more.

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Manning

Develop your skills with books, videos, and courses.

WyewWorks

Enabling companies to succeed by building software people love.

Pragmatic Studio

Courses that'll move you from confusion to "Aha, now I get it!"

View all our sponsors ❯

Categories:

Sub Categories:

Forums

Our Sponsors

Dashbit

Build Elixir applications with speed and confidence.

EEF

Supporting innovation across the BEAM ecosystem.

Coders51

We build reliable cloud platforms for business-critical systems.

AppSignal

Catch errors, track performance, monitor hosts and more.

Pragmatic Bookshelf

Practical resources that improve the lives of professional developers.

Manning

Develop your skills with books, videos, and courses.

WyewWorks

Enabling companies to succeed by building software people love.

Pragmatic Studio

Courses that'll move you from confusion to "Aha, now I get it!"

View all our sponsors ❯

We're in Beta

About us Mission Statement