我需要一个承诺中的承诺和它.然后先跑

Question

所以，我正在读取这个XML文件：

<GlDocumentInfo xmlns:opt="Opt.GL.Domain" xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="Opt.GL.BusinessLogic">
<world version="1.0.5">
<GlDocument key="GlDocument:1">
<GlDocumentNetwork>
<Network key="Network:1">
<Paths>
<Path key="Path:1" IsEmpty="False">
<PathNodes>
<PathNode key="PathNode:1" Node="Node:1" />
<PathNode key="PathNode:2" Node="Node:15" Distance="500" />
<PathNode key="PathNode:3" Node="Node:13" Distance="320" />
<PathNode key="PathNode:4" Node="Node:4" Distance="300" />
<PathNode key="PathNode:5" Node="Node:14" Distance="450" />
</PathNodes>
</Path>
<Path key="Path:2" IsEmpty="False">
<PathNodes>
<PathNode key="PathNode:5" Node="Node:14" />
<PathNode key="PathNode:6" Node="Node:4" Distance="450" />
<PathNode key="PathNode:7" Node="Node:13" Distance="300" />
<PathNode key="PathNode:8" Node="Node:15" Distance="320" />
<PathNode key="PathNode:9" Node="Node:1" Distance="500" />
</PathNodes>
</Path>
</Paths>
</Network>
</GLDocument>
</world>
</DocumentInfo>

Path是一个具有以下格式的模式：

var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var Path = new Schema({
key: {type: String, unique: true},
isEmpty: Boolean,
pathNodes: [String]
});
module.exports = mongoose.model('Path', Path);

PathNode是一个具有以下格式的模式：

var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var PathNode = new Schema({
key: String,
node: String,
distance: Number
});
module.exports = mongoose.model('PathNode', PathNode);

因此，我需要读取每个Path的每个PathNode，创建它们并将它们保存到DB，以及将当前路径的那些PathNodes保存在数组中，然后创建路径，并能够将数组分配给该路径的PathNodes属性，如您所见，该属性是这些PathNodes的字符串数组。我的代码是：

var PathNode = require('../models/pathNode');
var Path = require('../models/path');
var repository = require('../../repository');
var jsonConverted = JSON.parse(convert.xml2json(req.file.buffer.toString(), { compact: true, spaces: 4, alwaysChildren: true }));
var pathNodesArray = [];
await Promise.all(jsonConverted.GlDocumentInfo.world.GlDocument.GlDocumentNetwork.Network.Paths.Path.map(async path => {
pathNodesArray = [];
await Promise.all(path.PathNodes.PathNode.map(async pathNode => {
var newPathNode = new PathNode();
newPathNode.key = pathNode._attributes.key;
newPathNode.node = pathNode._attributes.Node; 
newPathNode.duration = pathNode._attributes.Duration;
newPathNode.distance = pathNode._attributes.Distance;
pathNodesArray.push(newPathNode.key);
repository.savePathNode(newPathNode);
})).then(async () => {
var newPath = new Path();
newPath.key = path._attributes.key;
newPath.isEmpty = path._attributes.IsEmpty.toString().toLowerCase();
Object.assign(newPath.pathNodes, pathNodesArray);
repository.savePath(newPath);
});
})).then(async () => {
(...) //doesn't matter for this question
}

读取工作正常，所有PathNodes都被创建并保存在DB中，问题是Path:1和Path:2都使用相同的PathNodes列表保存，Path：1具有Path：2中的PathNode列表。所以这个Promise和.然后outter Promise内部的不能正常工作，因为它正在读取所有路径节点，然后它才读取路径，并将最后一个组装的路径节点数组分配给最后一个路径。

你能帮我解决这个问题吗，这样每个路径都有相应的PathNodes？我已经尝试从多个位置删除异步，等待保存。。。非常感谢。

Answer 1

除了@Yevhenii提到的问题外，您的var pathNodesArray = [];位于错误的范围内。您希望每个路径都有自己的路径节点阵列，虽然在循环中执行pathNodesArray = [];可能会在顺序的情况下工作，但在并行处理路径时会失败。首选const而非var:

const PathNode = require('../models/pathNode');
const Path = require('../models/path');
const repository = require('../../repository');
const jsonConverted = JSON.parse(convert.xml2json(req.file.buffer.toString(), { compact: true, spaces: 4, alwaysChildren: true }));
const paths = jsonConverted.GlDocumentInfo.world.GlDocument.GlDocumentNetwork.Network.Paths.Path;
await Promise.all(paths.map(async path => {
const pathNodesArray = [];
//  ^^^^^ declare inside each iteration
await Promise.all(path.PathNodes.PathNode.map(async pathNode => {
const newPathNode = new PathNode({
key: pathNode._attributes.key,
node: pathNode._attributes.Node,
duration: pathNode._attributes.Duration,
distance: pathNode._attributes.Distance,
});
pathNodesArray.push(newPathNode.key);
await repository.savePathNode(newPathNode);
//      ^^^^^
}));
const newPath = new Path({
key: path._attributes.key,
isEmpty: path._attributes.IsEmpty.toString().toLowerCase(),
pathNodes: pathNodesArray,
});
await repository.savePath(newPath);
//  ^^^^^
}));
// … doesn't matter for this question

Answer 2

尝试在repository.savePathNode(newPathNode)之前添加return。现在，它接缝，你的嵌套承诺没有等待

...
await Promise.all(path.PathNodes.PathNode.map(async pathNode => {
var newPathNode = new PathNode();
newPathNode.key = pathNode._attributes.key;
newPathNode.node = pathNode._attributes.Node; 
newPathNode.duration = pathNode._attributes.Duration;
newPathNode.distance = pathNode._attributes.Distance;
pathNodesArray.push(newPathNode.key);
return repository.savePathNode(newPathNode);
}))
...