dokicro
Hi,
I am new to elixir and here is part of the code I dont like
slider = case Map.has_key?(attrs, :slider_id) do
true -> get_slider!(attrs.slider_id)
false -> get_slider!(attrs["slider_id"])
end
Reason for this is because when I do attrs = Map.put(attrs, :slider_id, slider.id) in sliders_test map key is atom
But when I do the same thing in slider_controller_test map key is string.
Where Next?
Trending in Questions
Other Trending Topics
Latest Phoenix Threads
Latest on Elixir Forum
Sponsor Spotlight
We build reliable cloud platforms for business-critical systems.
Categories:
Sub Categories:
Forums
Popular Tags
- #ecto
- #liveview
- #troubleshooting
- #learning-elixir
- #library
- #deployment
- #erlang
- #testing
- #genserver
- #mix
- #absinthe
- #remote-other
- #otp
- #plug
- #how-to-question
- #macros
- #postgres
- #elixirconf
- #channels
- #exunit
- #discussion
- #code-sync
- #podcasts
- #javascript
- #onsite
- #dialyzer
- #docker
- #authentication
- #ai
- #umbrella
- #full-time-contract
- #podcasts-by-brainlid
- #blog-post
- #ecto-query
- #elixirconf-us
- #elixir-ls
- #phoenix_html
- #iex
- #graphql
- #genstage
- #websockets
- #supervisor
- #advent-of-code
- #distillery
- #processes
- #elixirconf-eu
- #api
- #forms
- #security
- #hex
Our Sponsors
Build Elixir applications with speed and confidence.
We build reliable cloud platforms for business-critical systems.
Catch errors, track performance, monitor hosts and more.
Error tracking, logs, uptime, and Just Enough APM. Built for developers.
Elixir, Erlang & BEAM conferences from Code Sync - join us in 2026!
Practical resources that improve the lives of professional developers.
Bringing learning, work and compliance together since 1987.
The deployment platform built for Elixir: PaaS ease, VPS control.
The team behind Membrane, Popcorn, LiveDebugger. Available for hire.
Courses that'll move you from confusion to "Aha, now I get it!"
Showing Posts 1 to 10- Show Best Posts
- Show All (oldest first)
- Show All (newest first)
kokolegorille
You could…
As a rule of thumb, expect data coming from outside to be “key”, and after cast to be :key.
sorentwo
You would be best served treating all incoming params as having string keys. If you must accept either atom or string keys, then using
Map.get(“key”) || Map.get(:key)would be clearer than a case.dokicro
Thanks guys for your help, I agree that this is much cleaner syntax.
Nicd
To elaborate a bit, the reason why map keys from external sources (like user input) are strings, is that atoms are not garbage collected and there is a set maximum amount of atoms available in the system. If you exceed that amount, the VM will crash. So that’s why you shouldn’t create atoms from user input for example.
dokicro
But why is
phx gengenerating tests maps with keys?I tried to put
slider_idas string but I got this:expected params to be a map with atoms or string keys, got a map with mixed keysSo I should convert all pregenerated keys from atoms to string?
Example:
@valid_attrs %{description: "some description"}to
@valid_attrs %{"description" "some description"}mbuhot
The test maps should be automatically serialised to json by the phoenix test helpers, then deserialised to string-keyed maps in the Plug.Parsers plug declared in your endpoint module.
dokicro
They are only in controllers tests…
LostKobrakai
Params in contollers have string keys because anybody can send you any param and creating an atom for those would be a attack vector to crash the vm. It’s still generally adviced to work with atom keys in your business part of the app and to sanitize and atomize params before passing things forward into it.
sharkvan
This is interesting. In test that are generated by phx.gen.html the controller tests will have a fixture function that creates a test record with Ecto. But there is no changing of the atom keys to string keys. So if you do anything inside the context modules where you expect a string key from the controller your tests fail but the website works. Hmm, not great.
mbuhot
If you are getting anything other than string keyed params in Controllers then there is something wrong with the test.