Meteor is mostly backward compatible to even < 1.0 projects. Therefore lots of code is still callback based. So is the Meteor.call method. You can easily wrap it into a Promise-based approach:
export const callMethod = ({ name, args }) =>
new Promise((resolve, reject) => {
Meteor.call(name, args, (error, result) => {
if (error) {
return reject(error)
}
return resolve(result)
})
})
Although Meteor.call supports multiple arguments I rather prefer to pass a single object with named arguments to keep the code more expressive.
You can then use callMethod natively in an async environment:
Template.myTemplate.events({
'click .some-button': async function (event, templateInstance) {
const age = await callMethod({
name: 'getAge',
args: { name: 'John Doe' }
})
console.log(age) // whatever the method returned
}
})
Additionally you can "hook" into these calls and thus mix callbacks with promises and create a decent UX experience when method calls are part of user interactions:
export const callMethod = ({ name, args, prepare, receive, success, failure }) => {
// before call
if (typeof prepare === 'function') {
prepare()
}
// create the promise
const promise = new Promise((resolve, reject) => {
Meteor.call(name, args, (error, result) => {
// on received
if (typeof receive === 'function') {
receive()
}
if (error) {
return reject(error)
}
return resolve(result)
})
})
// on success
if (typeof success === 'function') {
promise.then(success)
}
// on error
if (typeof failure === 'function') {
promise.catch(failure)
}
return promise
}
The code can then be used for example to display a "waiting" indicator:
Template.myTemplate.events({
'click .update-button': async function (event, templateInstance) {
const updatedDoc = await callMethod({
name: 'updateUser',
args: { name: 'John Doe', age: 42 },
prepare: () => templateInstance.state.set('updating', true),
receive: () => templateInstance.state.set('updating', false),
failure: er => alert(er),
success: () => alert('updated')
})
// process updatedDoc if desired
})
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