Mixing
recursion with Promises
recursion with Promises
I have a collection in MongoDB like this
[
{
"classId": "1",
"name": "Input",
"definition": [
{
"property": [
{
"classId": "12",
"name": "One"
},
{
"classId": "8",
"name": "Comment"
}
]
}
]
},
{
"classId": "8",
"name": "CommentDetail",
"definition": [
{
"property": [
{
"classId": "10",
"name": "user"
},
{
"classId": "10",
"name": "message"
}
]
}
]
},
{
"classId": "10",
"name": "String",
"definition":
},
{
"classId": "12",
"name": "Int",
"definition":
}
]
Based on db above, I have a model to display
data = {
name:'',
template: ''
}
With classId=1, the expectation result is
{
"Name": "Input",
"temlate": "{['One': 'Int','Comment': ['user': 'String','message':'String']]}"
}
I try to using recursive promise to implement it. When property is empty, the result will be return.
Here is my function:
const getObjectTypeByClassId = (snapshotId, artifactId, objectType) => {
return artifactDetailModel.find({
'snapshotId': snapshotId,
'artifactId': artifactId
})
.then(data => {
let artifact = data[0];
let definition;
let definitionData = {};
return Promise.resolve()
.then(() => {
definition = artifact.data.teamworks.twClass[0].definition[0];
if (!lodash.isUndefined(definition.property)) {
const listOfProperty = definition.property;
for (let property of listOfProperty) {
classId = commonUtil.getArtifactId(property.classRef[0]);
if (!lodash.isUndefined(classId)) {
return getObjectTypeByClassId(snapshotId, classId, objectType);
}
}
} else {
definitionData.nameType = artifact.data.teamworks.twClass[0].elementAttribute.name;
definitionData.classId = artifact.data.teamworks.twClass[0].elementAttribute.id;
definitionData.template = bpmMapping.objectType[artifact.data.teamworks.twClass[0].elementAttribute.name];
return objectTypeModel.create(definitionData)
.then(obj => {
const response = {
name: objectType.name,
isArrayOf: objectType.isArrayOf,
nameType: obj.nameType,
template: obj.template,
}
return response;
})
}
})
})
}
Run with my function, the response is
data: {
Name: Input
temlate: user: String,
}
Please advice me.
async
await
@DanielA.White Using async/await in loops is non-blocking?
– dasfdsa
Jun 28 at 16:02
@dasfdsa: Could you please advise me?
– Phạm Quốc Bảo
Jun 29 at 8:41
I tried to. I tried to read your code but you haven't explained your problem well. Can you make your outputs more clear:
input: id=1 ==> output: Input:[ {IsActive[Output:String]}, {One: Int} ] or input: id=2 ==> output: {Output:String} , also please clarify what does your createObjectType does.– dasfdsa
Jun 29 at 9:12
input: id=1 ==> output: Input:[ {IsActive[Output:String]}, {One: Int} ] or input: id=2 ==> output: {Output:String}
createObjectType
@dasfdsa: I just updated my post, please help me review. It relate with the my previous post stackoverflow.com/questions/51056611/…
– Phạm Quốc Bảo
Jun 29 at 10:07
2 Answers
2
I tried it to some extent, but wasn't able to get it right. Plus your expected output is not the valid JSON "temlate": {} doesn't make sense.
It has nothing to do with Promise. You have to DFS you db array and created expected output. Here is what I have donup tillll now, you can think along those lines. But this is far from the solution.
"temlate": {}
Promise
let mainArray = [
{
"classId": "1",
"name": "Input",
"definition": [
{
"property": [
{
"classId": "12",
"name": "One"
},
{
"classId": "8",
"name": "Comment"
}
]
}
]
},
{
"classId": "8",
"name": "CommentDetail",
"definition": [
{
"property": [
{
"classId": "10",
"name": "user"
},
{
"classId": "10",
"name": "message"
}
]
}
]
},
{
"classId": "10",
"name": "String",
"definition":
},
{
"classId": "12",
"name": "Int",
"definition":
}
]
function dfs(root, createdRoot, fn, level) {
fn(root,createdRoot, level);
if(root.definition)/*if definition exists => keep traversing*/
root.definition[0].property.forEach(function (child) {
createdRoot.template = createdRoot.template || ;
let tempObj = {};
let lookupObj = lookupByClassId(child.classId);
tempObj[child.name] = lookupObj.name;
createdRoot.template.push(tempObj);
dfs(child,tempObj, fn, level + 1);
});
else /*if definition doesn't exist, look into the array*/
{
createdRoot.template = lookupByClassId(root.classId);
}
}
function lookupByClassId(classId){
for(let i=0;i<mainArray.length;++i){
let element =mainArray[i]
if(element.classId == classId)
return element;
}
}
let root = lookupByClassId(1);
createdRoot ={};
function func1(root, createdRoot, level) {
createdRoot.name = root.name;
console.log(root.classId);
}
dfs(root, createdRoot, func1, 0);
Thanks, bro. I just updated the answer, please have a look.
– Phạm Quốc Bảo
yesterday
here is the solution from a guy on the internet. it works well. Thanks, @Cuong Quach
var MongoClient = require('mongodb').MongoClient;
var database = 'testdequy';
var collection = 'classes';
MongoClient.connect("mongodb://localhost:27017/" + database, function (err, db) {
findDetails("1").then((r) => {
console.log("r>>>", r);
})
function findDetails(classId) {
var results = { Name: "", Template: "" };
var template = {};
return new Promise((main_resolve, reject) => {
process(template, "" , classId)
var works = 0;
function process(parent, childKey, objectId) {
return new Promise((resolve, reject) => {
db.collection(collection).find({ classId: objectId })
.toArray((err, docs) => {
if (results.Name == "") {
results.Name = docs[0].name;
}
let objectItem;
if (childKey == "")
objectItem = parent;
else
objectItem = parent[childKey];
console.log("ndocs", docs[0], objectId, objectItem)
if (docs[0].definition.length == 0 || docs[0].definition[0].property == undefined) {
let name = docs[0].name;
parent[childKey] = name;
console.log("nNo child", docs[0],parent, objectItem, docs[0].name)
resolve(0);
} else {
docs[0].definition[0].property.forEach((item) => {
works++;
//console.log("item", item)
let id = item.classId;
let name = item.name;
objectItem[name] = {};
process(objectItem, name, id).then((len)=>{
works--;
if(len == 0 && works == 0) main_resolve(template);
})
})
resolve(docs[0].definition[0].property.length)
}
})
})
}
})
}
});
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its because you return in your loop. consider using
async/awaitto simplify your code– Daniel A. White
Jun 28 at 15:53