Schemas can contain scalar-typed global variables.
global current_user_id: uuid;These provide a useful mechanism for specifying session-level data that can be
referenced in queries with the global keyword.
select User {
id,
posts: { title, content }
}
filter .id = global current_user_id;As in the example above, this is particularly useful for representing the notion of a session or “current user”.
Global variables are set when initializing a client. The exact API depends on which client library you’re using.
import createClient from 'edgedb';
const baseClient = createClient();
// returns a new Client instance that stores the provided
// globals and sends them along with all future queries:
const clientWithGlobals = baseClient.withGlobals({
current_user_id: '2141a5b4-5634-4ccc-b835-437863534c51',
});
await clientWithGlobals.query(`select global current_user_id;`);from edgedb import create_client
client = create_client().with_globals({
'current_user_id': '580cc652-8ab8-4a20-8db9-4c79a4b1fd81'
})
result = client.query("""
select global current_user_id;
""")
print(result)package main
import (
"context"
"fmt"
"log"
"github.com/edgedb/edgedb-go"
)
func main() {
ctx := context.Background()
client, err := edgedb.CreateClient(ctx, edgedb.Options{})
if err != nil {
log.Fatal(err)
}
defer client.Close()
id, err := edgedb.ParseUUID("2141a5b4-5634-4ccc-b835-437863534c51")
if err != nil {
log.Fatal(err)
}
var result edgedb.UUID
err = client.
WithGlobals(map[string]interface{}{"current_user": id}).
QuerySingle(ctx, "SELECT global current_user;", &result)
if err != nil {
log.Fatal(err)
}
fmt.Println(result)
}use uuid::Uuid;
let client = edgedb_tokio::create_client().await.expect("Client init");
let client_with_globals = client.with_globals_fn(|c| {
c.set(
"current_user_id",
Value::Uuid(
Uuid::parse_str("2141a5b4-5634-4ccc-b835-437863534c51")
.expect("Uuid should have parsed"),
),
)
});
let val: Uuid = client_with_globals
.query_required_single("select global current_user_id;", &())
.await
.expect("Returning value");
println!("Result: {val}");set global current_user_id :=
<uuid>'2141a5b4-5634-4ccc-b835-437863534c51';Global variables can be marked required; in this case, you must specify a
default value.
required global one_string: str {
default := "Hi Mom!"
};Global variables can also be computed. The value of computed globals are dynamically computed when they are referenced in queries.
required global random_global := datetime_of_transaction();The provided expression will be computed at the start of each query in which the global is referenced. There’s no need to provide an explicit type; the type is inferred from the computed expression.
Computed globals are not subject to the same constraints as non-computed ones;
specifically, they can be object-typed and have a multi cardinality.
global current_user_id: uuid;
# object-typed global
global current_user := (
select User filter .id = global current_user_id
);
# multi global
global current_user_friends := (global current_user).friends;Unlike query parameters, globals can be referenced inside your schema declarations.
type User {
name: str;
property is_self := (.id = global current_user_id)
};This is particularly useful when declaring access policies.
type Person {
required name: str;
access policy my_policy allow all using (.id = global current_user_id);
}Refer to Access Policies for complete documentation.
|
See also |
