Meteor 在模板辅助函数中使用 fetch 或 find 吗? [英] Meteor use fetch or find in template helper functions?

问题描述

在流星模板辅助函数中，如果我返回 find 与 fetch 的结果，在性能、重新渲染次数或其他任何方面是否有任何差异>?

Inside a meteor template helper function, is there any difference in performance, number of re-renders, or anything else if I return the result of a find vs a fetch?

例如查找方法:

Template.players.topScorers = function () {
  return Users.find({score: {$gt: 100}}, {sort: {score: -1}});
};

或添加提取:

Template.players.topScorers = function () {
  return Users.find({score: {$gt: 100}}, {sort: {score: -1}}).fetch();
};

仅查找方法是目前文档 中的内容，但我已经看到很多其他人使用 <代码>获取.

The find-only approach is what is currently in the docs, but I’ve seen lots of other people using fetch.

推荐答案

是的.

通过使用 fetch，您可以在现场注册对整个查询结果集的依赖.通过使用 find 和稍后使用 {{#each}} 进行迭代，一个依赖被分别注册到每个文档上.所以当一个文档发生变化时，只会重新渲染相关的代码.使用 fetch 时，更改结果集中的任何文档都会重新呈现您使用 fetch 的整个范围.

By using fetch you register a dependency on the entire query result set on the spot. By using find and later on iterating using {{#each}} a dependency is registered on every document separately. So when one document changes, only the relevant code is re-rendered. When using fetch, changing any document in the result-set would re-render the entire scope in which you used fetch.

对于小的结果集，它没有任何区别.对于频繁更改的较大集合，它可能会减慢计算速度并导致不希望的视觉伪影.

For small result-sets it doesn't make any difference. For larger sets with frequent changes it could slow down computation and cause undesired visual artefacts.

我写了一篇帖子帮助你理解它(虽然它没有直接回答你的问题)

I wrote a post which may help you understand it (it doesn't answer your question directly though)

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