I am facing with the problem that protobuf I defined enum but its value is int32
Now I want someway or somehow to change all the protobuf defined to string
Or any code-hack for doing it in gateway without changing the protobuf.
Enum defined
enum TimeUnit {
seconds = 0;
minutes = 1;
hours = 2;
days = 3;
months = 4;
}
message CacheDuration {
uint32 Value = 1;
TimeUnit Units = 2;
}
What i got from generated code now is
And it is the return value for front end to use. So they would see the value of Units = int32 like this:
The services communicate by generated struct protobuf.
I want to make it change to
"Units":"days"
Thanks
You can use String method in your go code:
generatedTimeUnitEnum.String() // output: days
I want to define a message that can have 2 fields (field A AND field B) XOR one other field (field C alone). I saw I can use the keyword oneof to set the XOR, but only between two fields.
how can I express my needs?
Ideally I want something like (not working)
syntax = "proto3";
message M {
oneof name {
{
string a = 1;
string b = 2;
}
string c = 3;
}
}
Only way I know of is to put the two fields a and b into separate submessage, which you can then put inside the oneof:
syntax = "proto3";
message A {
string a = 1;
string b = 2;
}
message M {
oneof name {
A a = 1;
string c = 3;
}
}
Alternatively you can put all fields into M without oneof. Describe the logic in the comments and check it manually in application code.
I have a message of the following type
message Foo {
string bar = 1;
float baz = 2;
}
Is there any problem in converting it to the following for use in Go ?
message Foo {
string bar = 1;
optional float baz = 2;
}
Is the preferred way to deprecate and create a new field in the proto in this case as well ?
depends on how deeply integrated that particular message is in your code base - meaning
are you storing the marshaled binary representation somewhere like your database
are different parts of your code base using different versions of the message you are modifying - e.g. older versions of your android/ios apps and such
point being if you use a message structure to unmarshal encoded data, that was not generated with the very same message structure, into - bad things will happen.
The docs recommend adding a new element to circumvent such scenarios entirely. If that is not something you want to do, take the above points into consideration.
The optional will make the field a pointer type. So in Go generated code, optional float will become *float32, which of course is not float32.
To deprecate a field, use [deprecated = true] field option:
message Foo {
string bar = 1;
float baz = 2 [deprecated = true];
}
If in subsequent releases of your protobuf schema you actually remove the field altogether from the message, you might want to add reserved 2, where 2 is the number of the field you removed.
message Foo {
string bar = 1;
reserved 2;
}
This helps preventing other people or future you from adding a new field in position 2. This is relevant in case you have outdated clients which still expect a float in position 2.
PS: optional fieds in Proto3 are supported from version 3.15
I suggest you to use the FloatValue type defined in the google.protobuf package. As example:
syntax = "proto3";
import "google/protobuf/wrappers.proto";
message Foo {
string bar = 1;
google.protobuf.FloatValue baz = 2;
}
Will generate a pb files with the content:
type Foo struct {
state protoimpl.MessageState
sizeCache protoimpl.SizeCache
unknownFields protoimpl.UnknownFields
Bar string `protobuf:"bytes,1,opt,name=bar,proto3" json:"bar,omitempty"`
Baz *wrapperspb.FloatValue `protobuf:"bytes,2,opt,name=baz,proto3" json:"baz,omitempty"`
}
You can use as follow:
f := Foo{
Bar: "Bar",
Baz: &wrapperspb.FloatValue{Value: float32(3)},
}
var floatValue float32
if f.Baz != nil {
floatValue = f.Baz.GetValue()
}
I have a protobuf schema with a bunch of repeated structures. Something like
syntax = "proto3";
package My
message TopLevel
{
string swVersion = 3;
string reportMac = 4;
string reportSsid = 6
}
message Temperature
{
required uint64 ts = 1;
required uint32 source = 3;
repeated sint32 readings = 4;
}
message MyMessage
{
required TopLevel topLevel = 1;
repeated Temperature temperature = 2;
}
I compile with pbtools and get the structures and functions for Temperature and readings. However I am having a hard time figuring out how to add "Temperature" entries dynamically.
Or am I out of luck and pbtools requires telling it ahead of time how many entries I have. One problem is data is encoded as it is generated and I do not know how many of what I will have for each report.
I attached the generated code.
pbtools requires the length before adding any items.
What I am looking for is a function that returns the message of a repeated field
I know there is Reflection::AddMessage which has the return type that I want but I do not want to add a message, just return an object of that message.
Here is an example of what I am trying to do let's say I have in the .proto file a message:
message Bar{
uint32 t x = 1;
uint64 t y = 2;
}
message Foo{
repeated Bar myMessage = 1;
}
I am using reflection to iterate through the Foo message and I want to be able to do something like this:
Message* Msg = createMessage(refl->FooMsg, FieldDesc)
I know there is also GetRepeatedMessage but that requires index.
First of all when the protobuf compiler generates the code for compiling you get an accessor function in the interface. The are functions mutable_nameOf_message() which returns the entire repeated field which is a std::vector in c++, or mutable_nameOf_message( index ) which gives you the specified element.
Now if you do not want to use Bar then you d'not need too.
message ArrayOfBar
{
repeated Bar arrayOfBar = 0;
message Bar{
uint32 t x = 1;
uint64 t y = 2;
}
}
If thats what you have hade in mind you could also be do something like this.
std::vector<Bar> arrayOfBars;
But that idea needs refinement because of the internal specifics of the Protobuf. Some unwanted behavior might occur with something like that.