英文:
Golang, MongoDB alert error when using `$facet` operator
问题
我将你的代码翻译成中文如下：
metadataStage := bson.D{
{"$facet", bson.D{
{"metadata", bson.A{bson.D{
{"$group", bson.D{
{"_id", nil},
{"total", bson.D{{"$sum", 1}}}}}}, // 获取满足以上所有条件的文档数量
}},
{"data", bson.A{bson.D{
//{"$sort", sortStage}, // 按字段和方向排序
{"$skip", skip}, // 跳过指定数量的文档
{"$limit", limit}}}}, // 限制文档数量
}},
}
但是当我运行代码时，Mongo驱动程序总是报错A pipeline stage specification object must contain exactly one field.。我不认为这是语法错误。请帮助我，非常感谢。
英文:
I set up my facet like that:
metadataStage := bson.D{
{"$facet", bson.D{
{"metadata", bson.A{bson.D{
{"$group", bson.D{
{"_id", nil},
{"total", bson.D{{"$sum", 1}}}}}}, // get number of documents that matches the all above conditions
}},
{"data", bson.A{bson.D{
//{"$sort", sortStage}, // sort by field and direction
{"$skip", skip}, // skip number of documents
{"$limit", limit}}}}, // limit them
}},
}
but when I run my code, Mongo Driver always alerts the error A pipeline stage specification object must contain exactly one field.. I do not think that this is a syntax error. Please help me, thank you so much
答案1
得分: 1
每个数据分面的管道应该是数组的元素
metadataStage := bson.D{
{"$facet", bson.D{
{"metadata", bson.A{
bson.D{{"$group", bson.D{
{"_id", nil},
{"total", bson.D{{"$sum", 1}}}}}}, // 获取符合上述条件的文档数量
}},
{"data", bson.A{
//bson.D{{"$sort", sortStage}}, // 按字段和方向排序
bson.D{{"$skip", skip}}, // 跳过指定数量的文档
bson.D{{"$limit", limit}}}}}, // 限制文档数量
}}
}
或者，你可以明确声明管道的阶段以便清晰理解。
metadataStage := bson.D{
{"$facet", bson.D{
{"metadata", mongo.Pipeline{
bson.D{{"$group", bson.D{
{"_id", nil},
{"total", bson.D{{"$sum", 1}}}}}}, // 获取符合上述条件的文档数量
}},
{"data", mongo.Pipeline{
//bson.D{{"$sort", sortStage}}, // 按字段和方向排序
bson.D{{"$skip", skip}}, // 跳过指定数量的文档
bson.D{{"$limit", limit}}}}}, // 限制文档数量
}}
}
英文:
Each pipeline for the data facet should be element of an array
metadataStage := bson.D{
{"$facet", bson.D{
{"metadata", bson.A{
bson.D{{"$group", bson.D{
{"_id", nil},
{"total", bson.D{{"$sum", 1}}}}}}, // get number of documents that matches the all above conditions
}},
{"data", bson.A{
//bson.D{{"$sort", sortStage}}, // sort by field and direction
bson.D{{"$skip", skip}}, // skip number of documents
bson.D{{"$limit", limit}}}}}, // limit them
}}
Alternately, you could write to be clear that you are declaring stages of the pipeline for the facets.
metadataStage := bson.D{
{"$facet", bson.D{
{"metadata", mongo.Pipeline{
bson.D{{"$group", bson.D{
{"_id", nil},
{"total", bson.D{{"$sum", 1}}}}}}, // get number of documents that matches the all above conditions
}},
{"data", mongo.Pipeline{
//bson.D{{"$sort", sortStage}}, // sort by field and direction
bson.D{{"$skip", skip}}, // skip number of documents
bson.D{{"$limit", limit}}}}}, // limit them
}}
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