CouchDB中的Like-condition [英] Like-condition in CouchDB

问题描述

我想在CouchDB中执行LIKE条件（SQL语法）。如何才能做到这一点？ LIKE条件将用于在浏览器中执行自动完成。

I want to perform a LIKE-condition (SQL syntax) in CouchDB. How can this be done? The LIKE-condition will be used to perform auto complete in the browser.

我想在输入字段中写co并获得结果Coffee，Couch，CouchDB等等。

I want to write "co" in the input field and get the results Coffee, Couch, CouchDB ect.

推荐答案

在字符串的开头搜索字母非常容易。您只需要一个视图，将您要搜索的字符串作为键发出。假设用户输入存储在变量 q 中，则使用参数 startkey = q 和 endkey = q +\\\￰。

It is very easy to search for letters at the beginning of a string. You just need a view that emits the string you want to search for as the key. Assuming the user input is stored in a variable q, you then call that view with the parameters startkey=q and endkey=q+"\ufff0".

这里的技巧是将最高的Unicode字符追加到搜索中串。在排序顺序中，此字符串位于以 q 开头的任何其他内容之后。 （这比@titanoboa建议的解决方案更容易实现，你需要增加用户输入的最后一个字母。）

The trick here is to append the highest possible Unicode character to the search string. In the sort order, this string comes after anything else starting with q. (This is much easier to implement than the solution suggested by @titanoboa, where you need to "increment" the last letter of the user input.)

如果你还想要为了能够在字符串中间找到单词（例如，在键入co时Colbert Report），您可以使用如下视图：

If you also want to be able to find words in the middle of a string (e.g. "The Colbert Report" when typing "co"), you could use a view like this:

function(doc) {
  if (doc.title) {
    var words = {};
    doc.title.replace(/\w+/g, function(word) {
      words[word.toLowerCase()] = true;
    });
    for (w in words) {
      emit(w, doc);
    }
  }
}

当然这只是建议短串。要在较长的文本中搜索，您应该查看全文搜索插件，如 couchdb-lucene 。

Of course this is only advisable for short strings. For searching in longer texts you should look into a full-text search add-on like couchdb-lucene.

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