enum with query_as_with()

[gmli]

Hi,

I’m looking for some help.

Currently I use a struct to fetch data from a MySQL database, and this struct has a enum field. Like this (shortened, there are other fields): 

#[derive(sqlx::FromRow, Debug, Clone)]
pub struct Row {
    pub input_type: Option<RowInputType>,
}

#[derive(Debug, Clone, PartialEq, Eq, sqlx::Type)]
#[sqlx(rename_all = "lowercase")]
pub enum RowInputType {
    Manure,
}

The enum column is defined like this (my query returns only manure variant): 

enum('treatment', 'variety', 'manure', 'supply')

While using the query_as!() macro I can use this syntax in the select to get the whole thing work : 

 table.input_type as "input_type: RowInputType",

But with the query_as_with() function, using the same syntax or not I could not get it to work. I get this kind of error : 

error occurred while decoding column \"input_type\": mismatched types; 
Rust type `core::option::Option<my_crate::some_module::RowInputType>` 
(as SQL type `ENUM`) is not compatible with SQL type `ENUM`

I’ve tried everything for several days, no success. Is it possible ? I must use query_as_with() function because I need my query to be build dynamically. I found several examples of what I’ve done with the macro, but no enum example with the function.

[joeydewaal]

It could be that you are running into #3387. Could you try with sqlx version 0.7.4?

[gmli]

Thank you for this link. I’m trying to downgrade to 0.7.4 but it’s a little bit tricky to get all dependencies right. Maybe I’ll try to make a minimal example project.

But in the meantime, the trick with the macro is the "type override". Isn’t it possible to use this type override with the function ?

[joeydewaal]

After reading through this again I think you're actually running into #3750. Downgrading to 0.7.4 unfortunately wont fix this issue.

[gmli]

But with the query_as!() macro it works, is it because the macro auto implement some traits ? To get it work this morning we had to implement : 

impl Type<sqlx::MySql> for RowInputType {...}

impl<'r> Decode<'r, sqlx::MySql> for RowInputType {...}

Perhaps the macro does this…

And the query_as_with() function relies on something else, maybe.

[joeydewaal]

My bad for the late reply, in the macro's you have to override the type (SELECT my_enum as "my_enum!: MyEnum") which disables type checking and make it work.