Actix-web: Add support for optional query parameters

[Dadibom]

I can't visit my page without every single query parameter defined

"Query deserialize error: missing field"

Add a way to make these optional, and/or add the ability to add defaults if they are not in the query

If this is already possible, add it to the documentation

[Dadibom]

found out you can use Option.. ignore me being a noob

[davepacheco]

How did you wind up doing this? I have the same question. I've tried having my handler function take an Option<Query<String>> as well as Query<Option<String>>, but I haven't figured out how to make it work. With the former, the param is just ignored. With the latter, I get:

Query deserialize error: invalid type: map, expected option

Edit: sorry for the noise. I misunderstood the interface. For anyone looking for this in the future: you've got to use Query<SomeStruct>, where SomeStruct derives Serialize, and then the fields in the struct can themselves be Options. Example:

#[derive(Deserialize)]
struct ListQueryParams {
    marker: Option<String>,
    limit: Option<usize>
}

async fn list(params: Query<ListQueryParams>)
    -> Result<HttpResponse, SomeError>
{
    ...
}

In this case, both marker and limit are optional query parameters.

[robertorojasr]

I used a couple of optional fields so I put them in a struct with optional fields, that way I'm not passing an Option but a struct, the fields are the Options

struct MyQuery {
    pub field_a: Option<String>,
    pub field_b: Option<i32>,
}

Then in the handler

 web::Query<MyQuery>

Works like a charm, I'm fairly new at this so if there is a better way, I'm interested :)

[robjtede]

To expand on the points made, the Query struct is used to extract the key-value pairs from the query string and uses Serde to do that.

If you want to extract the query-string in its entirety as a string then use req.query_string().

If you're after arbitrary field names then Query<HashMap<String, String>> will probably work for you.