Issue with a query builder

[sam701]

I'd like to have a SQL query builder. So I want to have some struct that holds some abstract query representation with the bound values. When the user is done with the query building, it should be possible somehow to get the final SQL query as a string containing ? or $1 and the bound values and pass them all to sql::query(query).bind(var1).bind(var2).

I took the Vec as an example. It might be any other container that holds the values, HashMap, etc. I got stuck at the very beginning.

Here is my code

trait SqlxValue<'q>: 'q + Send + Encode<'q, Postgres> + Type<Postgres>{}

#[tokio::main]
async fn main() -> Result<(), sqlx::Error> {
    let mut v: Vec<Box<dyn SqlxValue<'_>>> = Vec::new();
    v.push(Box::new(3));
    v.push(Box::new("str"));

    sqlx::query("insert into abc (a) values($1)")
        .bind(v.pop());
    Ok(())
}

But the Type is not object safe and I'm getting this error

50  |     let mut v: Vec<Box<dyn SqlxValue<'_>>> = Vec::new();
    |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^ `SqlxValue` cannot be made into an object
    = help: consider turning `type_info` into a method by giving it a `&self` argument or constraining it so it does not apply to trait objects
    = help: consider turning `compatible` into a method by giving it a `&self` argument or constraining it so it does not apply to trait objects
note: for a trait to be "object safe" it needs to allow building a vtable to allow the call to be resolvable dynamically; for more information visit <https://doc.rust-lang.org/reference/items/traits.html#object-safety>
   --> /Users/alexei/.cargo/registry/src/github.com-1ecc6299db9ec823/sqlx-core-0.5.9/src/types/mod.rs:175:8
    |
175 |     fn type_info() -> DB::TypeInfo;
    |        ^^^^^^^^^ ...because associated function `type_info` has no `self` parameter
...
184 |     fn compatible(ty: &DB::TypeInfo) -> bool {
    |        ^^^^^^^^^^ ...because associated function `compatible` has no `self` parameter

Question: how to define a container (Vec) that contains values that can be passed to the bind(..)?

[logistic-bot]

Have you found a solution to this? I also have the same problem