How can I write an edit controller

I have a nodeJS backend and a controller to add a specific function. There's an add function but there's no update function. how can I write an update function. I'm not good with backend and I have been tasked with this.

Below is the add function for the feature. How do I write a function like that for update:

async addRole(req, res, next) {
let body = req.body;
const model = new entityRoles(body);
try {
    const alreadyExist = await entityRoles.getByName(req.body.name);
    if (!alreadyExist) {
        const saveResponse = await model.save()
        return res.status(httpStatus.OK).json(new APIResponse(saveResponse, 'Entity role created successfully.', httpStatus.OK));

    } else if (alreadyExist.roleName === req.body.roleName) {
        res
            .status(httpStatus.OK)
            .send({ message: "name is already exist" });
    } else {
        res
            .status(httpStatus.OK)
            .send({ message: "Error Adding entity role" });
    }

} catch (e) {
    if (e.code === 11000) {
        return res
            .status(httpStatus.OK)
            .send({ message: "entity role is already exist with this name" });
    } else {
        return res.status(httpStatus.INTERNAL_SERVER_ERROR).json(new APIResponse({}, 'Error adding entity role', httpStatus.INTERNAL_SERVER_ERROR, e));
    }
}

EDIT: the framework used is express.js, ODM is mongoose and the database is mongodb

Your question isn't clear such as: framework, orm library, database. But this below code is sample that you can reference:

async function updateRole(req, res, next) {
/**
* Structure body
* @example
* {
*   id: 1, // id of role
*   name: 'admin' // new name of role
* }
*/
const body = req.body;
try {
const model = await entityRoles.findById(req.body.id);
/**
* Check have model exist on database
*/
if (!model) {
return res.status(httpStatus.OK).send({ message: 'not found role by id' });
}
/**
* Check new name of role is existed in database
*
* `body.name !== model.name` this statement make sure check role is correctly
* because always exist one role with old name that get from database in previous statement.
*/
if (body.name !== model.name && (await entityRoles.getByName(body.name))) {
return res.status(httpStatus.OK).send({ message: 'name is already exist' });
}
/**
* Add more your business logic at here such as check other filed or name is correctly
*/
/**
* Finally, model will be updated with new data and save to database.
*/
model.name = body.name;
/**
* Update rest of role
* @example 
* model.lastUpdatedAt = Date.now();
*/ 
const saveResponse = await model.save();
return res.status(httpStatus.OK).json(new APIResponse(saveResponse, 'Entity role updated successfully.', httpStatus.OK));
} catch (e) {
/**
* Check `code` of error to return client
*/
if (e.code === 11000) {
return res.status(httpStatus.OK).send({ message: 'name of role is existed. please update a other name.' });
} else {
return res
.status(httpStatus.INTERNAL_SERVER_ERROR)
.json(new APIResponse({}, 'Error adding entity role', httpStatus.INTERNAL_SERVER_ERROR, e));
}
}
}

async updateRole(req, res, next) {
try {
const roleId = req.params.id; // Extract the role ID from the request parameters
const updatedRoleData = req.body; // Extract the updated role information from the reque`enter code here`st body
const existingRole = await entityRoles.findById(roleId);
if (!existingRole) {
return res.status(httpStatus.NOT_FOUND).send({ message: "Role not found." });
}
// Update the existing role with the updated role information
existingRole.name = updatedRoleData.name;
existingRole.description = updatedRoleData.description;
// Update other properties as needed
const updatedRole = await existingRole.save();
return res.status(httpStatus.OK).json(new APIResponse(updatedRole, 'Role updated successfully.', httpStatus.OK));
} catch (error) {
return res.status(httpStatus.INTERNAL_SERVER_ERROR).json(new APIResponse({}, 'Error updating role.', httpStatus.INTERNAL_SERVER_ERROR, error));
}
}