Reading and writing to Schemas
Access to Schemas via code-generated libraries
Accessing Schemas via the libraries generated with the
schemagentool is the recommended way to use Schemas.
The schemagen tool of the Obelisk CLI can create libraries for each schema that wraps the low-level API of Schemas and types the results.
Assume the following configuration exists.
// definition of MySchema
import { DubheConfig } from "@0xobelisk/initia-common";
export const dubheConfig = {
name: "example",
description: "example desc",
schemas: {
student_management: {
data: [
{
name: "Class",
fields: {
name: "string",
teacher: "string",
},
},
{
name: "Student",
fields: {
name: "string",
age: "u8",
class: "Class",
},
},
],
structure: {
next_student_id: "StorageValue<u32>",
student_info: "StorageMap<u32, Student>",
},
events: [
{
name: "StudentAdded",
fields: {
student_id: "u32",
student: "Student",
},
},
{
name: "StudentRemoved",
fields: {
student_id: "u32",
},
},
],
},
},
} as DubheConfig;It’s a good idea to make a contains judgement before adding and removing records.
Existence of a record
student_management.borrow_next_student_id().contains_key()
student_management.borrow_student_info().contains_key(0)Adding a record && Updating a record
student_management.borrow_mut_next_student_id().set(0);
student_management.borrow_mut_student_info().set(
0,
student_management_student::new(
"Bob",
10,
student_management_class::new("Class 1", "Bob teacher")
));
// update
student_management.borrow_mut_student_info().mutate!(0, |student| {
*student = student_management_student::new(
"Bob",
10,
student_management_class::new("Class 1", "Bob teacher")
)});Deleting a record
student_management.borrow_mut_next_student_id().remove();
student_management.borrow_mut_student_info().remove(0);Retrieving a record
Make sure the record exists before getting
let next_student_id = student_management.borrow_next_student_id().get();
let maybe_next_student_id = student_management.borrow_next_student_id().try_get();
let student = student_management.borrow_student_info().get(0);
let maybe_student = student_management.borrow_student_info().try_get(0);