Question

我的应用程序通过QueryBuilder动态生成mongo查询。我试图这样做，以便传递的文本可以与我的集合中的几个字段进行比较。我需要遍历数据才能知道要添加到$ OR的内容（＆＃39; text_to_compare＆＃39; vs title字段，＆＃39; text_to_compare vs body字段），所以我一直试图存储BasicDBList中$ OR子句的每个部分如下：

BasicDBObject orsDBObject = new BasicDBObject();

BasicDBList orsList = new BasicDBList();

for( String dbFieldNameInstance: listDBFieldName ){

  QueryBuilder innerQB = new QueryBuilder();

  innerQB.put(dbFieldNameInstance).is(obj.getValue()); //using this inner QueryBuilder to assist in creating the document

  orsList.add(innerQB.get());

}

orsDBObject.putAll(orsList); //put each of the BasicDBList items into a BasicDBObject

qb.or(orsDBObject); //finally, add the entire $OR clause to my bigger querybuilder

System.out.println("qb: " + qb.get());

似乎我可能会跳过比必要更多的转化。它也不起作用。上面的输出最终看起来像这样：

qb：{＆＃34; $或＆＃34; ：[{＆＃34; 0＆＃34; ：{＆＃34; primary_industries_names＆＃34; ：＆＃34;电气＆＃34;}，＆＃34; 1＆＃34; ：{＆＃34; primary_industries_aliases＆＃34; ：＆＃34;电气＆＃34;}，＆＃34; 2＆＃34; ：{＆＃34; secondary_industries_names＆＃34; ：＆＃34;电气＆＃34;}，＆＃34; 3＆＃34; ：{＆＃34; secondary_industries_aliases＆＃34; ：＆＃34;电气＆＃34;}，＆＃34; 4＆＃34; ：{＆＃34; product_experience_names＆＃34; ：＆＃34;电气＆＃34;}，＆＃34; 5＆＃34; ：{＆＃34; product_experience_aliases＆＃34; ：＆＃34;电气＆＃34;}}]}

在大多数情况下，它看起来对我来说，但我不认为＆＃34; 0＆＃34;：应该出现在那里。任何建议都将不胜感激。

Answer 1

你有这种错误的方式。不重写你的代码，但你应该得到这个想法：

    // Before the loop
    QueryBuilder qb = new QueryBuilder();

    // And loop things like this
    for ( ) {
        qb.or(new BasicDBObject("this","that"));
    }

    // After loop

    System.out.println(qb.get());

如果您尝试嵌套多个条件，那么您似乎错过了$and运算符。请考虑以下事项：

    QueryBuilder qb = new QueryBuilder();

    for (int x=0; x<2;x++) {
        qb.or(new BasicDBObject("this","that"));
    }

    QueryBuilder qb2 = new QueryBuilder();

    qb2.and(qb.get());

    QueryBuilder qb3 = new QueryBuilder();
    for (int x=0; x<2;x++) {
        qb3.or(new BasicDBObject("something", "else"));
    }
    qb2.and(qb3.get());
    System.out.println(qb2.get());

如何将$ OR条件的BasicDBList传递给QueryBuilder？

1 个答案: