es 查询怎么排除那些只要有一条数据是空的字段_course

es 查询怎么排除那些只要有一条数据是空的字段 比如我es中的数据是这样的： ``` { "took": 28, "timed_out": false, "_shards": { "total": 5, "successful": 5, "failed": 0 }, "hits": { "total": 3, "max_score": 1, "hits": [ { "_index": "shop", "_type": "book", "_id": "AWlTdeg9-uKcfYQht2cG", "_score": 1, "_source": { "id": 10006573, "name": "Elasticsearch action", "author": "Radu Gheorghe", "num": 120, "content": "这本实战型的书籍聚焦在使用HTTP协议的Elasticsearch REST API代码片段的书写多数是使用cURL的bash脚本，所以很容易翻译成其他编程语言。", "price": 39.5, "published": "2018-10-01" } }, { "_index": "shop", "_type": "book", "_id": "AWlTkwr8-uKcfYQht2cH", "_score": 1, "_source": { "id": 20004812, "name": "Spring action", "author": "Radu go", "num": 120, "content": "这是一本简要简介spring d的书籍。", "price": 39.5 } }, { "_index": "shop", "_type": "book", "_id": "AWlTlIUH-uKcfYQht2cI", "_score": 1, "_source": { "id": 20004812, "name": "elasticsearch action", "author": "john" } } ] } } ``` 我要查询出来每条数据都不为空的字段，正确的结果应该是： { "id": 20004812, "name": "elasticsearch action", "author": "john" }

elasticSearch Java API 怎么匹配空字符串，不是null值是空字符串。_course

最近在公司的项目中用到了ES，再做查询索引的时候，有写条件是需要匹配ES索引的空字符串的，但是试了很多方法都没有成功。比如： 下面这种是匹配null值的： 但是就是不知道怎么匹配空字符串：