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Programming Phoenix Chapter 7 Flashcards | StudBud

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Programming Phoenix Chapter 7

7 terms·StudBud Administration·21 plays

Reviewing the concepts from chapter 7 of the book Programming Phoenix. #computerscience #programming #elixir #phoenix

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Questions 7

Answers

1
What foreign key columns will Ecto expect the videos table to have?
id
url, title, and description
user_id & category_id
user & category
2
2 minutes after running mix phoenix.gen, you notice that you misnamed a column. How to undo?
update all references to the column throughout the code
run mix ecto.rollback then git reset, start over
make a new migration to change the column name
You can't. You made your bed, now you sleep in it.
3
To just generate a model, a model test, and a migration, use…
mix phoenix.gen.model
mix phoenix.gen.channel
mix phoenix.gen.json
mix phoenix.gen.html
4
If every environment (every dev machine & prod) need certain data, define that data in…
the seeds file
a separate migration
the migration that creates the table
mix.exs
5
For a belongs_to relation, you make a migration to add a foreign key column to the table, and…
you add it to the model's changeset definition
you add a belongs_to line to the model's schema
…and Phoenix will notice it automatically and do the rest
you add a pipe_through [:belongs_to] in web/router.ex
6
The null: false at the end of the add line in a migration means...
every record must have a value in that column
it tells Phoenix to preload associations
it's how you actually create that column; null: true doesn't
the column is `false` by default
7
In a migration, what's something like create unique_index(:categories, [:name]) do?
raises an error if two records have the same name
helps the database find the record faster
lists all the category names
creates a file with a unique category name