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November 3, 2021 05:57
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Create a collection called idgen, create a document for every other collection, and store the self-add id
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| // Create a collection called idgen, create a document for every other collection, | |
| // and store the self-add id | |
| import ( | |
| "context" | |
| "go.mongodb.org/mongo-driver/bson" | |
| "go.mongodb.org/mongo-driver/mongo" | |
| "go.mongodb.org/mongo-driver/mongo/options" | |
| ) | |
| type idGenerate struct { | |
| ID int | |
| KEY string | |
| } | |
| func Next(coll string) (int, error) { | |
| update := bson.M{"$inc": bson.M{"id": 1}} | |
| idG := idGenerate{ID: 1} | |
| err := database.Collection("idgen"). | |
| FindOneAndUpdate(context.Background(), bson.M{"key": coll}, update).Decode(&idG) | |
| if err == mongo.ErrNoDocuments { | |
| _, err := database.Collection("idgen").InsertOne(context.Background(), bson.M{"key": coll, "id": 1}) | |
| if err != nil { | |
| ec <- err | |
| return 0, nil | |
| } else { | |
| return 0, nil | |
| } | |
| } else if err != nil { | |
| ec <- err | |
| return 0, err | |
| } else { | |
| return idG.ID, nil | |
| } | |
| } |
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