std::net::IpAddr cannot bind to INET (postgres)

[h-m-88]

I have bound an IpAddr type to a column of type INET(postgres) as shown below, but sqlx is expecting an IpNetwork type.

The official documentation states that the std::net::IpAddr type and INET type are compatible based on the ipnet features flag.

https://docs.rs/sqlx/latest/sqlx/postgres/types/index.html#ipnet

Am I using it wrong somehow?

CREATE TABLE sensor_logs (
    id              SERIAL PRIMARY KEY,
    host_name       VARCHAR(128) NOT NULL,
    ip_address      INET NOT NULL,
    collected       TIMESTAMP NOT NULL,
    extra           JSONB
);

let result = sqlx::query!(
            r#"
            INSERT INTO sensor_logs (host_name, ip_address, collected, extra)
            VALUES ($1, $2, $3, $4)
            RETURNING id
            "#,
            sensor_log_row.host_name,
            IpAddr::V4("192.168.1.2".parse().unwrap()), // here
            sensor_log_row.collected,
            extra_json
        )
        .fetch_one(self.txn().as_mut())
        .await?;

error[E0308]: mismatched types
  --> crates/libs/ds-pgsql/src/repository_impl.rs:81:13
   |
81 |             IpAddr::V4("192.168.1.2".parse().unwrap()),
   |             ^^^^^^
   |             |
   |             expected `IpNetwork`, found `IpAddr`
   |             expected due to the type of this binding
   |
help: call `Into::into` on this expression to convert `std::net::IpAddr` into `sqlx::types::ipnetwork::IpNetwork`
   |
81 |             IpAddr.into()::V4("192.168.1.2".parse().unwrap()),
   |                   +++++++

[harshagarwalnyu]

The reason you're seeing a mismatch is that Postgres's INET type isn't just an IP address: it's an IP address plus a network prefix (like /32 or /128). While std::net::IpAddr represents the address, it doesn't carry that prefix information, which is why sqlx defaults to more specific types.

To fix this, you should use the IpNetwork type from the ipnetwork crate (if you have that feature enabled in sqlx). It converts seamlessly from IpAddr:

use ipnetwork::IpNetwork;

// Convert your IpAddr into the network type sqlx expects
let ip_param: IpNetwork = sensor_log_row.ip_address.into();

let result = sqlx::query!(
    r#"INSERT INTO sensor_logs (ip_address) VALUES ($1) RETURNING id"#,
    ip_param
)
.fetch_one(pool)
.await?;

If you don't want to bring in another type, you can use a type cast directly in your SQL string. This tells the query! macro to handle the conversion internally for a single IP:

let result = sqlx::query!(
    r#"INSERT INTO sensor_logs (ip_address) VALUES ($1::inet) RETURNING id"#,
    sensor_log_row.ip_address // std::net::IpAddr works here with the cast
)
.fetch_one(pool)
.await?;

Make sure you have features = ["postgres", "ipnetwork"] (or ipnet) enabled in your Cargo.toml. Usually, casting in the SQL is the quickest way to stay with standard library types.

[h-m-88]

Thank you for your advice.

This time, I solved the problem by implementing ipnet::IpNet.

As you pointed out, it seems that casting std::net::IpAddr to ($1::inet) in the SQL query
would also easily solve the problem, wouldn't it? (I haven't tried it though.)
I didn't know that. I'm glad I learned something new.

However, because collecting IP addresses requires various complex internal company procedures,
I ultimately stopped the collection.