Await and Async callbacks hell - promise

Question

I want to make the UserDataGenerator class works like a traditional SYNC class.
My expectation is that userData.outputStructure can give me the data prepared.
let userData = new UserDataGenerator(dslContent)
userData.outputStructure
getFieldDescribe(this.inputStructure.tableName, field) is a ASYNC call which invokes Axios.get
Below is my current progress but it's still not waiting for the data ready when I print out the userData.outputStructure
export default class UserDataGenerator {
inputStructure = null;
outputStructure = null;
fieldDescribeRecords = [];
constructor(dslContent) {
this.outputStructure = Object.assign({}, dslContent, initSections)
process()
}
async process() {
await this.processSectionList()
return this.outputStructure
}
async processSectionList() {
await this.inputStructure.sections.map(section => {
this.outputStructure.sections.push(this.processSection(section));
})
}
async processSection(section) {
let outputSection = {
name: null,
fields: []
}
let outputFields = await section.fields.map(async(inputField) => {
return await this._processField(inputField).catch(e => {
throw new SchemaError(e, this.inputStructure.tableName, inputField)
})
})
outputSection.fields.push(outputFields)
return outputSection
}
async _processField(field) {
let resp = await ai
switch (typeof field) {
case 'string':
let normalizedDescribe = getNormalizedFieldDescribe(resp.data)
return new FieldGenerator(normalizedDescribe, field).outputFieldStructure
}
}

Answer 1

You're trying to await arrays, which doesn't work as you expect. When dealing with arrays of promises, you still need to use Promise.all before you can await it - just like you cannot chain .then on the array.
So your methods should look like this:
async processSectionList() {
const sections = await Promise.all(this.inputStructure.sections.map(section =>
this.processSection(section)
));
this.outputStructure.sections.push(...sections);
}
async processSection(section) {
return {
name: null,
fields: [await Promise.all(section.fields.map(inputField =>
this._processField(inputField).catch(e => {
throw new SchemaError(e, this.inputStructure.tableName, inputField)
})
))]
};
}