如何使用bson.ObjectId字段正确解组mgo结果到结构中

Question

I'm using the mgo package for Mongo database interactions.

I currently have a base struct that looks like:

type Document struct {
    ID bson.ObjectId `bson:"_id"` // Unique document _id.

    EntityId bson.ObjectId `bson:"entity_id"` // Used to create relationships between collections.

    EffectiveDate time.Time `bson:"effective_date"` // Date this document becomes effective.

    // Audit Fields.
    CreatedAt time.Time     `bson:"created_at"`
    CreatedBy bson.ObjectId `bson:"created_by"`

    UpdatedAt time.Time     `bson:"updated_at"`
    UpdatedBy bson.ObjectId `bson:"updated_by"`

    // Document state(stale, current, etc..)
    IsActive  bool `bson:"is_active"`
    IsDeleted bool `bson:"is_deleted"`
    IsMaster  bool `bson:"is_master"`

    ExternalID string `bson:"external_id"`

    CompanyID bson.ObjectId `bson:"company_id"` // The unique ObjectId for that company.
}

I embedded this Document struct into more specific collection defined structs that look like:

// Represents a product-category document.
type ProductCategory struct {
    Document // Embedded base document struct contains all base fields.

    Name       string `bson:"name"`        // Name of the category
    CategoryID string `bson:"category_id"` // Unique id of the category.
}

I'm able to run queries like this one below and get all the fields I need besides the bson.ObjectId fields including ID(_id).

  var pc collections.ProductCategory
    col := session.DB("some_db").C("product-category")

    col.Find(nil).One(&pc)

    // All fields are here besides [Id, CompanyId, CreatedBy, UpdatedBy] etc..

Is there any glaring issues on why the Fields I need aren't being added to the struct?

Answer 1

You need to use the inline flag:

type ProductCategory struct {
    Document `bson:",inline"`
    // other fields ...
}

See the bson Marshal docs for more info:

inline     Inline the field, which must be a struct or a map,
           causing all of its fields or keys to be processed as if
           they were part of the outer struct. For maps, keys must
           not conflict with the bson keys of other struct fields.