Read request body two times in Golang [duplicate] - json

Question

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How to read multiple times from same io.Reader
(5 answers)
Closed 4 years ago.
type ValidationModel struct {
Name string `json:"name" valid:"alpha,required~Name is required"`
Email string `json:"email" valid:"email~Enter a valid email.,required~Email is required."`
Password string `json:"password" valid:"required~Password is required"`
}
validationModel := ValidationModel{}
json.NewDecoder(r.Body).Decode(&validationModel)
_, err := govalidator.ValidateStruct(validationModel)
First I am validating the request body using govalidator.
type UserModel struct {
ID bson.ObjectId `json:"_id" bson:"_id"`
Name string `json:"name" bson:"name"`
Email string `json:"email" bson:"email"`
Password string `json:"password,omitempty" bson:"-"`
PasswordHash string `json:"-" bson:"passwordHash"`
Salt string `json:"-" bson:"salt"`
Token string `json:"token,omitempty" bson:"-"`
}
user := models.UserModel{}
json.NewDecoder(r.Body).Decode(&user)
fmt.Println(user)
And after validating the request, again I am decoding the request body into user struct, but the request body has been read once using validationModel, so when I try to again decode it into user, it is not giving me any values.
I can think of two solutions here:
Store request body in one separate variable, and use that variable two times.
Copy validationModel values in user.
But I don't have any idea about to implement these approaches and which approach is best to follow. Or is there any other solution which can be implemented?
Thanks in advance.

Answer 1

Storing the data can be easily done with ioutil.ReadAll():
data, err := ioutil.ReadAll(r.Body)
If you need the data back as a io.Reader (which is how the r.Body is), then you can use bytes.NewReader():
reader := bytes.NewReader(data)
And ACTUALLY, r.Body is a io.ReadCloser, so if you need that you can use ioutil.NopCloser() in conjunction with bytes.NewReader():
reader := ioutil.NopCloser(bytes.NewReader(data))