CODEWITHSUNDEEP
jsonmongodbgonosql
Tomasz Makowski
Tomasz Makowski

Reputation: 103

convert result into JSON without structs using mongo-go-driver

I don't want to use structs before converting results into JSON. Let's say I have some results: 

result, err := collection.Find(ctx, filter, options)

I can collect all results in docs variable and last result in doc variable:

    var doc bson.Raw
    var docs []bson.Raw    
    for result.Next(ctx) {
            document, err := result.DecodeBytes()
            if err != nil {
                log.Println(err)
            }
            doc = document
            docs = append(docs, doc)
        }

I can easily convert last result into JSON without using any structs:

var jsonDoc bson.M
err = bson.Unmarshal(doc, &jsonDoc)
return jsonDoc

I can't convert docs into JSON and use as a result in my Rest server.

Update 2019-01-17:

I'm using result in my REST server like this:

user.GET("/booking/customer/:id", func(c *gin.Context) {
    result := GetAllCustomerBookings(c.Param("id"))
    c.JSON(http.StatusOK, result)
})

so it can't be a loop through values. The question: how to convert []bson.Raw to []byte or bson.Raw. Let's imagine that now I have {JSON} in each value of array. I need one JSON like this: [{JSON}, {JSON}, ...].

Using nodejs was easier because I could send all records in one JSON document. Go and mongodb-go-driver needs to go through all records and I don't know how to build one JSON document.

Nodejs and mongodb equivalent:

router.get('/bookings/customer/:id', function (req, res, next) {
    db.Bookings.find({
        "booking.customer._id": {
            $eq: req.params.id
        }
    }).sort({
            "booking.arrival_date": -1
        },
        function (err, bookings) {
            if (err) {
                res.send(err);
            } else {
                res.json(bookings);
            }
        });
});

Upvotes: 4

Views: 4826

Answers (2)

Kasra Karami
Kasra Karami

Reputation: 441

you can also use this:

var results []bson.M
if err := cursor.All(context.TODO(), &results); err != nil {
    log.Panic(err)
}

and for see the result or convert to json use this:

res, _ := json.Marshal(results)
fmt.Println(string(res))

If you would like do it by your own you can do this:

var convertedResult []map[string]interface{}
for _, item := range results {
    convertedItem := make(map[string]interface{})
    for key, val := range item {
        switch v := val.(type) {
        case primitive.ObjectID:
            convertedItem[key] = v.Hex()
        case bson.M:
            subMap := make(map[string]interface{})
            for subKey, subVal := range v {
                subMap[subKey] = subVal
            }
            convertedItem[key] = subMap
        case bson.A:
            subArray := make([]interface{}, len(v))
            for i, subVal := range v {
                subArray[i] = subVal
            }
            convertedItem[key] = subArray
        default:
            convertedItem[key] = v
        }
    }
    convertedResult = append(convertedResult, convertedItem)
}

jsonBytes, err := json.Marshal(convertedResult)
if err != nil {
    panic(err)
}
jsonString := string(jsonBytes)

fmt.Println(jsonString)

Upvotes: 0

Tomasz Makowski
Tomasz Makowski

Reputation: 103

This code works. After few hours of trying and thanks to good luck I managed to solve this issue. Maybe someone will explain this?

Instead of bson.Raw I used bson.M and result.Decode() instead of result.DecodeBytes() Now I have the same output as nodejs gives me.

 var docs []bson.M
    for result.Next(ctx) {
        var document bson.M
        err = result.Decode(&document)
        if err != nil {
            log.Println(err)
        }
        docs = append(docs, document)
    }
    return docs

Upvotes: 4

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