Question

我正在使用嵌套函数调用两个方法来复制一组文档。这些文档来自两个不同的集合，但是由treeBranches字段链接，如下所示。

树木收藏

{ 
    _id: "tree_1", 
    treeBranches: ["branch_1","branch_2"], 
    ... 
}

分支集合

{ 
    _id: "branch_1", 
    branchName: "Branch 1", 
    ... 
}
{ 
    _id: "branch_2", 
    branchName: "Branch 2", 
    ... 
}

我不明白如何在_id中获取每个现有分支文档的branches.forEach。现在，当我运行它时，会创建多个分支文档，但每个分支文档都会复制第一个现有分支，而不管存在多少分支文档。如何修改var currentBranchId = Branches.findOne({})._id;以获取此_id并正确循环设置？

编辑编辑以收集答案

    Template.Actions.events({
    'change .action-selection': function(e) {
        e.preventDefault();

        var selection = $(e.target).val();

        var currentTreeId = this._id;
        var branches = Branches.find({_id:{$in:this.treeBranches}});

        switch(selection) {
            case "tree-repeat":
                return Meteor.call('treeRepeat', currentTreeId, function () {
                    branches.forEach(function(b) {
                        var currentBranchId = b._id; 
                        Meteor.call('treeBranchesRepeat', currentBranchId, function (branchId) {
                        });
                    });
                });
                break;
                …
            }
        }
    });

    Meteor.methods({
        treeRepeat: function(currentTreeId) {
            check(currentTreeId, String);

        var tree = Trees.findOne({_id:currentTreeId}, {fields:{_id:0, treeBranches:0}});

        var treeExtended = _.extend(tree, {
            treeBranches: [?]//NEED IDS FROM NEW BRANCHES
        });

        var treeId = Trees.insert(treeExtended);

            return {
                _id: treeId
            };
        },
        treeBranchesRepeat: function(currentBranchId) {
            check(currentBranchId, String);

            var branch = Branches.findOne({_id:currentBranchId}, {fields: {_id: 0}});

            var branchId = Branches.insert(branch);

            return {
                _id: branchId
            };
        }
    });

Answer 1

您可以使用forEach迭代光标（就像数组一样），例如：

var cursor = Branches.find();
cursor.forEach(function(b){ // b will be a single branch document
  console.log(b._id); // you can get its _id directly
  console.log(b.branchName); // or any other key
});

对游标执行forEach()然后在循环中执行findOne是没有意义的，因为forEach()将依次将每个对象传递给匿名函数。

从您的问题中不清楚您如何确定哪个分支属于哪个树。

如果我想创建原始Trees集合的非规范化副本，我可能会执行以下操作：

var treeCursor = Trees.find();
treeCursor.forEach(function(tree){
  DenormalizedTrees.insert({_id: tree._id}); // reuse the same _id
  tree.treeBranches.forEach(function(id){ // now iterate over the array of branch ids
    var branch = Branches.findOne(id);
    DenormalizedTrees.update(tree._id,{ $push: { treeBranches: branch }});
  });
});

forEach over cursor

1 个答案: