英文:
how to create bson map based on input
问题
我正在使用mgo库在golang中构建一个bson映射。我想重构一些代码以避免重复。
考虑以下代码：
bson.M {
"$match" : bson.M{
"xyz" : "abc",
},
"$id_1" : value_1,
}
和另一个类型的bson映射：
bson.M {
"$match" : bson.M{
"xyz" : "abc",
},
"$id_2" : value_2,
}
我如何将这两个结合起来（从一个函数中构建bson.M并返回，value1/2是该函数的参数），以便根据value_1是否为空字符串或value_2是否为空字符串来使用。
例如：如果我构建以下函数。我的意图是通过调用buildBsonObject("123","")来构建第一种类型的映射（参见上面的代码），通过调用buildBsonObject("", "456")来构建第二种类型的映射。
func buildBsonObject (value_1 string, value_2 string) {
return bson.M {
"$match" : bson.M{
"xyz" : "abc",
},
"$id_1" : value_1,
"$id_2" : value_2,
}
}
如果我这样做（参见buildBsonObject函数），那么当value_1为空字符串时，我的mongo聚合查询将无法工作，因为它会将id_1视为""，而我打算在我的bson对象中只有id_2。
有关如何解决这个问题的建议。谢谢。
英文:
I am building a bson map in golang using mgo library. I want to refactor some code to be able to avoid duplication.
Consider this:
bson.M {
"$match" : bson.M{
"xyz" : "abc",
},
"$id_1" : value_1,
}
and another bson map of type:
bson.M {
"$match" : bson.M{
"xyz" : "abc",
},
"$id_2" : value_2,
}
How can I combine the two (build bson.M from a function and return, value1/2 are params to this func) to be used based on if value_1 is empty string or value_2 is empty string.
For example: if I build a the following function. My intention is to build map of first type (see above) by calling buildBsonObject("123","") and the second one by calling buildBsonObject("", "456").
func buildBsonObject (value_1 string, value_2 string) {
return bson.M {
"$match" : bson.M{
"xyz" : "abc",
},
"$id_1" : value_1,
"$id_2" : value_2,
}
}
If I do the following (see function buildBsonObject), then when value_1 is empty string, my mongo aggregation query will not work since it will treat as id_1 being "", whereas I intended to just have id_2 in my bson object.
Any suggestions on how to do this. Thanks.
答案1
得分: 0
这是翻译好的内容：
如何看待这段代码：
func buildBsonObject(value_1 string, value_2 string) bson.M {
m := bson.M{
"$match": bson.M{
"xyz": "abc",
},
}
if value_1 != "" {
m["$id_1"] = value_1
}
if value_2 != "" {
m["$id_2"] = value_2
}
return m
}
[playground 示例](http://play.golang.org/p/Z09GrQr5gl)
另一种方法是将键名传递给函数：
```go
func buildBsonObject(k string, v string) bson.M {
return bson.M{
"$match": bson.M{
"xyz": "abc",
},
k: v,
}
}
[playground 示例](http://play.golang.org/p/G3XRK1fKfY)
英文:
How about this:
func buildBsonObject(value_1 string, value_2 string) bson.M {
m := bson.M{
"$match": bson.M{
"xyz": "abc",
},
}
if value_1 != "" {
m["$id_1"] = value_1
}
if value_2 != "" {
m["$id_2"] = value_2
}
return m
}
An alternative is to pass the key name to the function:
func buildBsonObject(k string, v string) bson.M {
return bson.M{
"$match": bson.M{
"xyz": "abc",
},
k: v,
}
}
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论