Working with types

The surrealdb-types crate provides the SurrealValue trait, the kind! macro and the value constructors used to move data between Rust and SurrealDB.

The surrealdb-types crate holds the public value type system shared across SurrealDB. It is kept separate from the database core so that types and type conversions can be used on their own, without pulling in the whole database, but it is also available from the main surrealdb crate under the surrealdb::types path.

The `SurrealValue` trait

SurrealValue is the trait that converts a Rust type to and from a SurrealDB value. Deriving it is all that is needed to use a Rust type for serialisation and deserialisation. To customise how a type is converted, such as renaming fields or tagging enum variants, see SurrealValue attributes.

use surrealdb::engine::any::connect;
use surrealdb::types::SurrealValue;

#[derive(Debug, SurrealValue)]
struct Employee {
    name: String,
    active: bool,
}

#[tokio::main]
async fn main() {
    let db = connect("memory").await.unwrap();

    db.use_ns("ns").use_db("db").await.unwrap();

    let mut res = db
        .query("CREATE employee:bobby SET name = 'Bobby', active = true")
        .await
        .unwrap();

    let bobby = res.take::<Option<Employee>>(0).unwrap().unwrap();

    // Employee { name: "Bobby", active: true }
    println!("{bobby:?}");
}

The SurrealValue trait can be implemented manually via three methods: one to indicate the matching SurrealDB type, a second to convert into a SurrealDB Value, and a third to convert out of a SurrealDB Value.

use surrealdb::engine::any::connect;
use surrealdb::types::{Datetime, Error, Kind, SurrealValue, Value};

#[derive(Debug)]
struct MyOwnDateTime(i64);

impl SurrealValue for MyOwnDateTime {
    fn kind_of() -> Kind {
        Kind::Datetime
    }

    fn into_value(self) -> Value {
        Value::Datetime(Datetime::from_timestamp(self.0, 0).unwrap())
    }

    fn from_value(value: Value) -> Result<Self, Error>
    where
        Self: Sized,
    {
        match value {
            Value::Datetime(n) => Ok(MyOwnDateTime(n.timestamp_millis())),
            _ => Err(Error::thrown("No good".to_string())),
        }
    }
}

#[tokio::main]
async fn main() {
    let db = connect("memory").await.unwrap();

    db.use_ns("main").use_db("main").await.unwrap();

    println!(
        "{:?}",
        db.query("time::now()")
            .await
            .unwrap()
            .take::<Option<MyOwnDateTime>>(0)
    );
}

An example of successful and unsuccessful conversions into the user-created MyOwnDateTime struct:

#[tokio::main]
async fn main() {
    let db = connect("memory").await.unwrap();

    db.use_ns("main").use_db("main").await.unwrap();

    println!(
        "{:?}\n",
        db.query("time::now()")
            .await
            .unwrap()
            .take::<Option<MyOwnDateTime>>(0)
    );

    println!(
        "{:?}",
        db.query("CREATE person")
            .await
            .unwrap()
            .take::<Option<MyOwnDateTime>>(0)
    );
}

Output:

Ok(Some(MyOwnDateTime(1760330504574)))

Err(InternalError("Couldn't convert Object(Object({\"id\": RecordId(RecordId { table: \"person\", key: String(\"tcblzaktx3ponin9dyci\") })})) to MyOwnDateTime"))

The `kind!` macro

The crate includes a kind! macro which allows a SurrealQL type to be used directly instead of its Rust equivalent.

This macro is especially useful when working with types like literals which are similar to enums but can specify exact possible values in a way that Rust would require deriving TryFrom to work. In this case, the SurrealValue trait can be implemented manually and the kind! macro used for its kind_of() method.

fn kind_of() -> surrealdb_types::Kind {
    kind!({ status: "good" } | { status: "goodwithnotification", notification: string} | { status: "error", at: datetime, reason: string })
}

This is technically possible without the macro, but requires a lot more boilerplate. Here is the output when using cargo expand to show the generated code for the example above.

fn kind_of() -> surrealdb_types::Kind {
    surrealdb_types::Kind::Either(
        vec!([
            surrealdb_types::Kind::Literal(
                surrealdb_types::KindLiteral::Object(
                    std::collections::BTreeMap::from([
                        (
                            "status".to_string(),
                            surrealdb_types::Kind::Literal(
                                surrealdb_types::KindLiteral::String("good".to_string()),
                            ),
                        ),
                    ]),
                ),
            ),
            surrealdb_types::Kind::Literal(
                surrealdb_types::KindLiteral::Object(
                    std::collections::BTreeMap::from([
                        (
                            "status".to_string(),
                            surrealdb_types::Kind::Literal(
                                surrealdb_types::KindLiteral::String(
                                    "goodwithnotification".to_string(),
                                ),
                            ),
                        ),
                        ("notification".to_string(), surrealdb_types::Kind::String),
                    ]),
                ),
            ),
            surrealdb_types::Kind::Literal(
                surrealdb_types::KindLiteral::Object(
                    std::collections::BTreeMap::from([
                        (
                            "status".to_string(),
                            surrealdb_types::Kind::Literal(
                                surrealdb_types::KindLiteral::String("error".to_string()),
                            ),
                        ),
                        ("at".to_string(), surrealdb_types::Kind::Datetime),
                        ("reason".to_string(), surrealdb_types::Kind::String),
                    ]),
                ),
            ),
            ]),
        ),
}

The following example shows the kind! macro used for a Rust enum that manually implements SurrealValue, along with examples of its use from the Rust side to the SurrealDB side, and vice versa.

use surrealdb::engine::any::connect;
use surrealdb_types::{Datetime, Error, Object, SurrealValue, ToSql, Value, kind};

#[derive(SurrealValue)]
struct MyError {
    at: Datetime,
    reason: String,
}

enum Response {
    Good,
    GoodWithNotification(String),
    Error(MyError),
}

impl SurrealValue for Response {
    fn kind_of() -> surrealdb_types::Kind {
        kind!({ status: "good" } | { status: "goodwithnotification", notification: string} | { status: "error", at: datetime, reason: string })
    }

    fn into_value(self) -> Value {
        let mut obj = Object::new();
        match self {
            Response::Good => {
                obj.insert("status", "good");
            }
            Response::GoodWithNotification(n) => {
                obj.insert("status", "goodwithnotification");
                obj.insert("notification", n);
            }
            Response::Error(e) => {
                obj.insert("status", "error");
                obj.insert("at", e.at);
                obj.insert("reason", e.reason);
            }
        }
        Value::Object(obj)
    }

    fn from_value(value: Value) -> Result<Self, Error>
    where
        Self: Sized,
    {
        let Value::Object(o) = value else {
            return Err(Error::thrown("Should have been an object".to_string()));
        };
        let Some(Value::String(status)) = o.get("status") else {
            return Err(Error::thrown(
                "Error trying to get 'status' field".to_string(),
            ));
        };
        match status.as_str() {
            "Good" => Ok(Response::Good),
            status @ "GoodWithNotification" => {
                Ok(Response::GoodWithNotification(status.to_string()))
            }
            "Error" => {
                let Some(Value::Datetime(at)) = o.get("at") else {
                    return Err(Error::thrown("Error trying to get 'at' field".to_string()));
                };
                let Some(Value::String(reason)) = o.get("reason") else {
                    return Err(Error::thrown(
                        "Error trying to get 'reason' field".to_string(),
                    ));
                };
                Ok(Response::Error(MyError {
                    at: at.clone(),
                    reason: reason.clone(),
                }))
            }
            _ => Err(Error::thrown("No status field for some reason".to_string())),
        }
    }

    fn is_value(value: &Value) -> bool {
        value.is_kind(&Self::kind_of())
    }
}

#[tokio::main]
async fn main() {
    let db = connect("memory").await.unwrap();
    db.use_ns("main").use_db("main").await.unwrap();

    // Turning DB results into Rust enum
    let mut statuses = db.query("
        { status: 'Good' };
        { status: 'GoodWithNotification', notification: 'We need things to make us go. We need help.' };
        { status: 'Error', at: d'1914-07-28', reason: 'General conflagration'};
    ").await.unwrap();

    println!(
        "Good: {}",
        statuses
            .take::<Option<Response>>(0)
            .unwrap()
            .unwrap()
            .into_value()
            .to_sql_pretty()
    );
    println!(
        "Good with notification: {}",
        statuses
            .take::<Option<Response>>(1)
            .unwrap()
            .unwrap()
            .into_value()
            .to_sql_pretty()
    );
    println!(
        "Error: {}",
        statuses
            .take::<Option<Response>>(2)
            .unwrap()
            .unwrap()
            .into_value()
            .to_sql_pretty()
    );

    // Turn Rust enum into Values,
    // use them in the CONTENT clause
    // and then print the result
    let good = Response::Good;
    let good_but = Response::GoodWithNotification("Keep it up!".into());
    let error = Response::Error(MyError {
        at: Datetime::now(),
        reason: "Error: can't think of interesting error message".into(),
    });

    println!(
        "Good: {:?}",
        db.query("CREATE result CONTENT $content")
            .bind(("content", good))
            .await
            .unwrap()
            .take::<Option<Value>>(0)
            .unwrap()
            .unwrap()
            .to_sql()
    );
    println!(
        "Good but: {:?}",
        db.query("CREATE result CONTENT $content")
            .bind(("content", good_but))
            .await
            .unwrap()
            .take::<Option<Value>>(0)
            .unwrap()
            .unwrap()
            .to_sql()
    );
    println!(
        "Error: {:?}",
        db.query("CREATE result CONTENT $content")
            .bind(("content", error))
            .await
            .unwrap()
            .take::<Option<Value>>(0)
            .unwrap()
            .unwrap()
            .to_sql()
    );
}

Value construction macros

Alongside kind!, the crate exports four macros for building values by hand: object!, array!, set! and vars!. Each is available from surrealdb::types as well as from surrealdb_types directly.

Macro	Builds	Notes
`object!`	`Object`	Keys can be bare identifiers or quoted string literals
`array!`	`Array`	Uses square brackets, like `vec!`
`set!`	`Set`	Deduplicates its items; takes `Value`s, not raw Rust values
`vars!`	`Variables`	Same syntax as `object!`, used for `.bind()` after `.query()`

Values passed to object!, array! and vars! only need to implement SurrealValue, so ordinary Rust types can be used directly.

use surrealdb::types::{Value, array, object, set};

fn main() {
    let obj = object! {
        name: "Aeon",
        age: 30,
        "home-town": "Bregna",
    };

    let arr = array![1, "two", true];

    let tags = set! {
        Value::from_t("rust"),
        Value::from_t("surrealdb"),
        Value::from_t("rust"),
    };

    println!("{obj:?}");
    println!("{arr:?}");
    println!("{tags:?}");
}

Output:

Object({"age": Number(Int(30)), "home-town": String("Bregna"), "name": String("Aeon")})
Array([Number(Int(1)), String("two"), Bool(true)])
Set({String("rust"), String("surrealdb")})

Note the two differences between array! and set!. set! drops the duplicate "rust", and it does not convert its items for you: each one must already be a Value. Passing set! { 1, 2, 3 } will not compile, while array![1, 2, 3] will.

The `vars!` macro

vars! builds a Variables map, which is what the .bind() method on a query takes. It is the most direct way to pass more than one parameter into a query.

use surrealdb::engine::any::connect;
use surrealdb::types::{RecordId, SurrealValue, vars};

#[derive(Debug, SurrealValue)]
struct Person {
    id: RecordId,
    name: String,
    age: i64,
}

#[tokio::main]
async fn main() -> surrealdb::Result<()> {
    let db = connect("mem://").await?;
    db.use_ns("main").use_db("main").await?;

    let sql = "
        CREATE type::table($table) SET name = $name, age = $age;
        SELECT * FROM type::table($table) WHERE age >= $min_age;
    ";

    let mut result = db
        .query(sql)
        .bind(vars! {
            table: "person",
            name: "Aeon",
            age: 30,
            min_age: 18,
        })
        .await?;

    let created: Option<Person> = result.take(0)?;
    dbg!(created);
    let adults: Vec<Person> = result.take(1)?;
    dbg!(adults);
    Ok(())
}

Variables is an ordinary struct as well as a macro target. Variables::new() followed by .insert() builds the same value at runtime, which is the better choice when the set of parameters is not known when the code is written.

Convenience methods for the `Value` type

Importing the SurrealValue trait gives access to a lot of convenience methods.

One example is the .into_value() method which converts a large number of Rust standard library types into a SurrealQL Value.

use surrealdb_types::{SurrealValue, Value};

fn main() {
    let string_val = "string".into_value();
    assert!(string_val.is_string());
    assert_eq!(string_val, Value::String("string".into()));
}

One more example of .into_value() to convert a HashMap<String, &'str> into a Value:

use std::collections::HashMap;

use surrealdb::engine::any::connect;
use surrealdb_types::{SurrealValue, Value};

#[tokio::main]
async fn main() {
    let db = connect("memory").await.unwrap();
    db.use_ns("db").use_db("db").await.unwrap();

    let mut map = HashMap::new();
    map.insert("name".to_string(), "Billy");
    map.insert("id".to_string(), "person:one");

    // Turn HashMap into SurrealDB Value
    let as_person = map.into_value();

    // Object(Object({"id": String("person:one"), "name": String("Billy")}))
    println!("{as_person:?}");

    // Insert it into a query to create a record
    let res = db
        .query("CREATE ONLY person CONTENT $person")
        .bind(("person", as_person))
        .await
        .unwrap()
        .take::<Value>(0)
        .unwrap();

    // Object(Object({"id": RecordId(RecordId { table: "person", key: String("person:one") }), "name": String("Billy")}))
    println!("{res:?}");
}

A Value can be manually constructed using any of the various structs and enums contained within it. This is particularly useful when constructing a complex ID made up of a table name and an array for the key.

use std::str::FromStr;

use surrealdb::engine::any::connect;
use surrealdb_types::{Array, Datetime, RecordId, RecordIdKey, Value};

#[tokio::main]
async fn main() {
    let db = connect("memory").await.unwrap();
    db.use_ns("db").use_db("db").await.unwrap();

    let date = "2025-10-13T05:16:11.343Z";

    let complex_id = RecordId {
        table: "weather".into(),
        key: RecordIdKey::Array(Array::from(vec![
            Value::String("London".to_string()),
            Value::Datetime(Datetime::from_str(date).unwrap()),
        ])),
    };

    let mut res = db
        .query("CREATE ONLY weather SET id = $id")
        .bind(("id", complex_id))
        .await
        .unwrap();

    // Object(Object({"id": RecordId(RecordId { table: "weather", key: Array(Array([String("London"), Datetime(Datetime(2025-10-13T05:16:11.343Z))])) })}))
    println!("{:?}", res.take::<Value>(0).unwrap());
}

The .is() method for a Value returns true if the type(s) in question can be converted to the type indicated when the method is called.

use std::collections::HashMap;
use surrealdb_types::SurrealValue;

fn main() {
    // true
    println!("{}", "string".into_value().is::<String>());

    let mut map = HashMap::new();
    map.insert("name".to_string(), "Billy");
    map.insert("id".to_string(), "person:one");

    // true
    println!("{}", map.clone().into_value().is::<HashMap<String, &str>>());
    // Also true
    println!("{}", map.into_value().is::<HashMap<String, String>>());
}

A Value can be converted into a serde_json::Value using the .into_json_value() method, and vice versa using .into_value().

use surrealdb::engine::any::connect;
use surrealdb_types::{SurrealValue, Value};

#[tokio::main]
async fn main() {
    let db = connect("memory").await.unwrap();
    db.use_ns("db").use_db("db").await.unwrap();

    let value = db
        .query("CREATE ONLY person:one SET age = 21")
        .await
        .unwrap()
        .take::<Value>(0)
        .unwrap();

    // Object(Object({"age": Number(Int(21)), "id": RecordId(RecordId { table: "person", key: String("one") })}))
    println!("{value:?}");
    // Object {"age": Number(21), "id": String("person:one")}
    println!("{:?}", value.clone().into_json_value());

    // Round trip
    value.into_json_value().into_value();
}

The SurrealValue trait

The kind! macro

Value construction macros

The vars! macro

Convenience methods for the Value type

The `SurrealValue` trait

The `kind!` macro

The `vars!` macro

Convenience methods for the `Value` type