Question

我们现有的代码包含很少基于集合操作的writeResult的操作，如：

WriteResult writeResult = dbCollection.insert(new BasicDBObject(someDoc));
    if(writeResult.wasAcknowledged()) {
        response.setSuccess(true);
    }

使用升级的mongo更改操作会产生如下结果：

WriteResult writeResult = dbCollection.insertOne(new BasicDBObject(someDoc)); // this won't work
    if (writeResult.wasAcknowledged()) {
        response.setSuccess(true);
    }

问题是对集合的操作是void，如果我查看文档 -

WriteResult.java

/**
 * Returns true if the write was acknowledged.
 *
 * @return true if the write was acknowledged
 * @see com.mongodb.WriteConcern#UNACKNOWLEDGED
 * @since 3.0
 */
public boolean wasAcknowledged() {
    return acknowledged;
}

WriteConcern.java

/**
 * Write operations that use this write concern will return as soon as the message is written to the socket. Exceptions are raised for
 * network issues, but not server errors.
 *
 * @since 2.10.0
 * @mongodb.driver.manual core/write-concern/#unacknowledged Unacknowledged
 */
public static final WriteConcern UNACKNOWLEDGED = new WriteConcern(0);

我尝试修改代码以获得如下结果：

collection.withWriteConcern(WriteConcern.UNACKNOWLEDGED).insertOne(document);

但是，我现在如何使用当前代码实现前一逻辑的条件部分？

Answer 1

根据MongoCollection

的文件

 /**
 * Inserts the provided document. If the document is missing an identifier, the driver should generate one.
 *
 * @param document the document to insert
 * @throws com.mongodb.MongoWriteException        if the write failed due some other failure specific to the insert command
 * @throws com.mongodb.MongoWriteConcernException if the write failed due being unable to fulfil the write concern
 * @throws com.mongodb.MongoException             if the write failed due some other failure
 */
void insertOne(TDocument document);

如果由于无法满足写入问题而导致写入失败，则插入操作应抛出com.mongodb.MongoWriteConcernException

所以你的代码可以转换为：

try {
   dbCollection
       .withWriteConcern(WriteConcern.ACKNOWLEDGED)
       .insertOne(new BasicDBObject(someDoc));

   response.setSuccess(true);
} catch (MongoWriteConcernException x) {
   response.setSuccess(false);
}

在上面的mongodb 3.3.0中确认了执行标志

1 个答案: