小编Sku*_*fle的帖子

我正在尝试创建一个管道,它将计算有多少文档符合某些条件.我看不出在条件中使用正则表达式的任何方法.这是带有注释的管道的简化版本:

db.Collection.aggregate([
    // Pipeline before the issue
    {'$group': {
        '_id': {
            'field': '$my_field', // Included for completeness
        },
        'first_count': {'$sum': {                    // We're going to count the number
            '$cond': [                               // of documents that have 'foo' in 
                {'$eq: ['$field_foo', 'foo']}, 1, 0  // $field_foo.
            ] 
        }},                                       

        'second_count': {'$sum': {                       // Here, I want to count the
            '$cond': [                                   // Number of documents where
                {'$regex': ['$field_bar', regex]}, 1, 0  // the value of 'bar' matches
            ]                                            // the regex 
        }},                                          
    }, …