Question

我刚开始使用Amazon Web Services SimpleDB开展项目。在一种方法中，我试图通过使用select query来确定域已经包含的项目数。

代码如下所示：

AmazonSimpleDBClient *dbClienet = [[AmazonSimpleDBClient alloc]initWithAccessKey:_secret withSecretKey:_hiddenSecret];
NSString *countRequestString = [NSString stringWithFormat:@"select count(*) from %@",domain];
SimpleDBSelectRequest *countRequest = [[SimpleDBSelectRequest alloc]initWithSelectExpression:countRequestString];
SimpleDBSelectResponse *countResponse = [dbClienet select:countRequest];

这很好用。例如：连接工作，当我记录它时，响应似乎也是正确的：

{Items: (
"{Name: Domain,AlternateNameEncoding: (null),Attributes: (\n    \
"{Name: Count,AlternateNameEncoding: (null),Value: 2,AlternateValueEncoding: (null),<SimpleDBAttribute: 0x756f730>}\"\n),<SimpleDBItem: 0x7529d00>}"),NextToken: (null),{BoxUsage: 0.000023,{requestId: b683ed01-9e5f-9041-1ace-cbb0fdfaa799}}}

我接下来要做的是将值2保存到NSInteger itemCount。这是我挣扎的地方。我尝试了几件事，我来的最远的是：

NSInteger itemCount = [[[[[countResponse.items objectAtIndex:0]attributes]objectAtIndex:1]value]integerValue];

这应该适用于我的眼睛。但它引发了错误：

Multiple methods named 'value' found with mismatched result, parameter type or attributes

有人能指出我哪里出错了吗？我真的被困在这里了。

谢谢，塞巴斯蒂安

Answer 1

感谢geraldWilliam的评论我明白了：

    NSString *countRequestString = [NSString stringWithFormat:@"select count(*) from %@",domain];
    SimpleDBSelectRequest *countRequest = [[SimpleDBSelectRequest alloc]initWithSelectExpression:countRequestString];
    SimpleDBSelectResponse *countResponse = [dbClienet select:countRequest];
    NSArray* attributes = [[countResponse.items objectAtIndex:0]attributes];
    for (SimpleDBAttribute*attr in attributes) {
        if ([attr.name isEqualToString:@"Count"]) {
            itemCount = [attr.value integerValue];
        }
    }

这种方法有效。

AWS iOS SDK simpleDB项目计数

1 个答案: