generate insert struct to enable autoincrement / serial usage

[thomas725]

The current diesel getting started guide makes use of a serial (postgres) / autoncrement (sqlite) primary key and tells the reader to write an additional insert model struct to be able to make use of that database feature.

I'd love it if there where a way to generate a separate insert struct that skips columns with auto-increment and default values.

Even nicer would be if those fields where generated as options - even when they're defined as not null - since there's still a sensible scenario for them being None on creation before inserting them to the database = to make use of those defaults defined on the SQL side. But I guess that's something diesel itself would need to support and I'm not sure if it does.

[abbychau]

updated in the latest version. could you have a look?

[nnbyte]

As I understand it, it is now possible in Diesel to skip_insertion that would allow to skip a field for #[derive(Insertable)].

Also, check out the diesel's rustdoc.

Also, what I undestood from Diesel's author himself, is that it is a very common misconception that is best practice to generate separate "insert structs"!

[thomas725]

thank you @abbychau - looks great :)

adding the option --add-table-name causes two instances of this use line:
use diesel::prelude::*;

Also, the --derive option is ignored. I'd like to be able to make those structs also derive Debug in addition to Insertable.

@nnbyte thank you for your input! I'd love to see how that should look in practice - why does the getting started guide use separate insertable structs if it's not the best practice to do so? You're first link leads to a 404, I believe you wanted it to point here: diesel-rs/diesel#860 (comment)

This is my script for updating my generated models at the moment:

cargo install --git "https://github.com/LukasLohmar/diesel_cli_ext" --branch dev
diesel_ext --import-types "crate::schema::*" --add-table-name --struct-attribute "#[diesel(check_for_backend(diesel::sqlite::Sqlite))]" --derive "Queryable, Selectable, Debug" > src/models_queryable.rs

cargo install diesel_cli_ext
diesel_ext --import-types "crate::schema::*" --derive "Insertable, Debug" --insertable > src/models_insertable.rs

At the moment I need to install your original and @LukasLohmar 's fork alternating because only your original version supports generating the Insertable structs, while only @LukasLohmar 's fork allows the usage of the --struct-attribute parameter. See also: #67

And while I'm at it ;) I'd also love an option to control (prevent) the output of those clippy allow lines.

[nnbyte]

@nnbyte thank you for your input! I'd love to see how that should look in practice - why does the getting started guide use separate insertable structs if it's not the best practice to do so?

You are welcome! This is a very good question for Diesel's devs! My assumption is that the getting started guide was written a long time ago and was not updated to reflect the changes. Btw, I was also confused after reading it. However the devs are clear in their comments that I linked.

[thomas725]

I've now merged both your @abbychau new --insertable feature and @LukasLohmar 's --struct-attribute feature into a new fork:

cargo install --git "https://github.com/thomas725/diesel_cli_ext" --branch master

[thomas725]

And now I first tried to actually use the generated code, it doesn't compile because:

lifetime parameter 'a is never used
consider removing 'a, referring to it in a field, or using a marker such as PhantomData

For an entity that has only a single non-key & non-default field of type Vec<u8>. I guess that could be defined as a slice of an u8 array with that lifetime, but instead it is generated as Vec just like for the queryable struct.