使用mgo管道功能时未完全检索到数据

Question

I was using pipe function in mgo to retrieve data. My data structs are as follows.

type Company struct {
    Id              bson.ObjectId `bson:"_id,omitempty"`
    CompanyName     string
    Slug            string
    CompanyUsers    []CompanyUser
}
type CompanyUser    struct {
    UserName    string
    Email       string
    FullName    string
}

I needed to check whether a given "UserName" is present under "CompanyUsers" in a "Company" with a given "Slug".

Both Slug and UserName are provided by the User.

Using Pipe function I successfully done the search, but the data is returned with an empty CompanyUsers array.

My query is as follows:

var companyResults []Company

pipeline := []bson.M{
    {"$match": bson.M{"slug": slug}},
    {"$unwind": "$companyusers"},
    {"$match": bson.M{
        "companyusers.username": username,
    }},
}
err := c.Pipe(pipeline).All(&companyResults)

This provides me a search result as follows:

[{ObjectIdHex("573aa0fddd731711c94830ca") MyCompany companyslug [] }]

None of the data in CompanyUsers are retrieved. How can I solve this error?

Answer 1

Try making companyResults a []map[string]interface{} instead of a []Company to see what sort of a result you get. This helps to figure out what the structure of companyResults should be.

var companyResults []map[string]interface{}

You will see a result like,

[map[companyname:MyCompany slug:companyslug companyusers:map[username:username] _id:test]]

See that companyusers is infact a map not an array. This is because your usage of the $unwind stage. It deconstructs the array, outputting one document for each element in the array. See docs.

I agree with John Smith's answer, that you do not need pipelines at all. But following should give you the desired result.

type Result struct {
    Id           string `bson:"_id,omitempty"`
    CompanyName  string
    Slug         string
    CompanyUsers CompanyUser
}

var companyResults []Result