Re: [protobuf] How to erase particular field with MergeFrom()

[Benjamin Krämer]

And instead of encapsulating the field mask into a new message, you should 
be alright to just use google.protobuf.FieldMask as it is already a message 
by itself (in case that you don't add other data to RepAndOptMask of 
course).

Am Dienstag, 17. Mai 2016 10:51:04 UTC+2 schrieb Denis Bakhvalov:
>
>
> message RepAndOptMask
> {
> google.protobuf.FieldMask field_mask = 1;
> }
>
> I think there is nothing wrong if I will send them separately, right?
>

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Re: [protobuf] How to erase particular field with MergeFrom()

['Feng Xiao' via Protocol Buffers]

On Tue, May 17, 2016 at 1:49 AM, Denis Bakhvalov 
wrote:

> Hi Feng Xiao,
>
> Thanks for your reply!
>
> Unfortunately I couldn't find good examples how to use it, so let me ask
> one more question:
>
> Should I put mask as a part of original message:
>
> message RepAndOpt
> {
> repeated string name = 1;
> string surname = 2;
>
> google.protobuf.FieldMask field_mask = 3;
> }
>
> or put it as standalone message?
>
> message RepAndOptMask
> {
> google.protobuf.FieldMask field_mask = 1;
> }
>
> I think there is nothing wrong if I will send them separately, right?
>
It's probably more clear to put it separately from the original message
it's applied to, but either one works.


>
> понедельник, 16 мая 2016 г., 22:14:33 UTC+2 пользователь Feng Xiao написал:
>>
>>
>>
>> On Wed, May 11, 2016 at 5:09 AM, Denis Bakhvalov 
>> wrote:
>>
>>> Hi,
>>>
>>> Suppose I have such message structure:
>>>
>>>
>>> package msg_RepAndOpt;
>>>
>>> message RepAndOpt{
>>> repeated string name = 1;
>>> optional string surname = 2;
>>> ...
>>> // there are lots of others.}
>>>
>>>
>>> And I have two components that have copies of this message:
>>>
>>>
>>> // component1:RepAndOpt A;
>>> A.add_name("Name");
>>> A.set_surname("Surname");
>>> // component2:RepAndOpt B;
>>>
>>>
>>> In my case components modify those messages via transaction mechanism.
>>> It means that if one component changes some field it also sends it to
>>> another component to propagate those changes. Component-receiver is doing
>>> merge:
>>>
>>>
>>> // Component2 modifies B and sends it to component1.// Component1 perfoms 
>>> merge:
>>> A.MergeFrom(B);
>>>
>>>
>>> Now, say, component2 wants to erase field "name". If it will send clear
>>> B message (default construction) than:
>>>
>>>- - MergeFrom() will not modify A;
>>>- - CopyFrom() will erase also other fields.
>>>
>>> Another way will be to fill B with the contents of A, clear name field
>>> and component1 will use CopyFrom(). But this is not acceptable because
>>> system is really high-loaded and there could be lots of other fields. So,
>>> desired solution to clean name field is:
>>>
>>>1. 1. Component2 create B message.
>>>2. 2. Explicitly stores information that it want to erase only name
>>>field.
>>>3. 3. Component1 perform A.MergeFrom(B).
>>>4. 4. Result: A::name is cleared but other fields are left untouched.
>>>
>>> As far as I tested this applies to repeated and optional fields. Is
>>> there any ready-to-use solution or I should modify protobuf implementation?
>>>
>> I think you can do this using FieldMaskUtil:
>>
>> https://github.com/google/protobuf/blob/beta-3/src/google/protobuf/util/field_mask_util.h#L111
>>
>> You create an empty B message along with a FieldMask containing only the
>> field you want to clear, and use FieldMaskUtil::MergeMessageTo(A,
>> field_mask, )  to replace the field in A with the value from B.
>>
>>
>>
>>> --
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>>> Groups "Protocol Buffers" group.
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>>> an email to protobuf+u...@googlegroups.com.
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>>> For more options, visit https://groups.google.com/d/optout.
>>>
>>
>> --
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Re: [protobuf] How to erase particular field with MergeFrom()

[Denis Bakhvalov]

Hi Feng Xiao,

Thanks for your reply!

Unfortunately I couldn't find good examples how to use it, so let me ask 
one more question:

Should I put mask as a part of original message:

message RepAndOpt
{
repeated string name = 1;
string surname = 2;

google.protobuf.FieldMask field_mask = 3;
}

or put it as standalone message?

message RepAndOptMask
{
google.protobuf.FieldMask field_mask = 1;
}

I think there is nothing wrong if I will send them separately, right?

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Re: [protobuf] How to erase particular field with MergeFrom()

[Denis Bakhvalov]

Hi Feng Xiao,

Thanks for your reply!

Unfortunately I couldn't find good examples how to use it, so let me ask 
one more question:

Should I put mask as a part of original message:

message RepAndOpt
{
repeated string name = 1;
string surname = 2;

google.protobuf.FieldMask field_mask = 3;
}

or put it as standalone message?

message RepAndOptMask
{
google.protobuf.FieldMask field_mask = 1;
}

I think there is nothing wrong if I will send them separately, right?

понедельник, 16 мая 2016 г., 22:14:33 UTC+2 пользователь Feng Xiao написал:
>
>
>
> On Wed, May 11, 2016 at 5:09 AM, Denis Bakhvalov  > wrote:
>
>> Hi,
>>
>> Suppose I have such message structure:
>>
>>
>> package msg_RepAndOpt;
>>
>> message RepAndOpt{
>> repeated string name = 1;
>> optional string surname = 2;
>> ...
>> // there are lots of others.}
>>
>>
>> And I have two components that have copies of this message:
>>
>>
>> // component1:RepAndOpt A;
>> A.add_name("Name");
>> A.set_surname("Surname");
>> // component2:RepAndOpt B;
>>
>>
>> In my case components modify those messages via transaction mechanism. It 
>> means that if one component changes some field it also sends it to another 
>> component to propagate those changes. Component-receiver is doing merge:
>>
>>
>> // Component2 modifies B and sends it to component1.// Component1 perfoms 
>> merge:
>> A.MergeFrom(B);
>>
>>
>> Now, say, component2 wants to erase field "name". If it will send clear B 
>> message (default construction) than:
>>
>>- - MergeFrom() will not modify A;
>>- - CopyFrom() will erase also other fields.
>>
>> Another way will be to fill B with the contents of A, clear name field 
>> and component1 will use CopyFrom(). But this is not acceptable because 
>> system is really high-loaded and there could be lots of other fields. So, 
>> desired solution to clean name field is:
>>
>>1. 1. Component2 create B message.
>>2. 2. Explicitly stores information that it want to erase only name 
>>field.
>>3. 3. Component1 perform A.MergeFrom(B).
>>4. 4. Result: A::name is cleared but other fields are left untouched.
>>
>> As far as I tested this applies to repeated and optional fields. Is there 
>> any ready-to-use solution or I should modify protobuf implementation?
>>
> I think you can do this using FieldMaskUtil:
>
> https://github.com/google/protobuf/blob/beta-3/src/google/protobuf/util/field_mask_util.h#L111
>
> You create an empty B message along with a FieldMask containing only the 
> field you want to clear, and use FieldMaskUtil::MergeMessageTo(A, 
> field_mask, )  to replace the field in A with the value from B.
>
>  
>
>> -- 
>> You received this message because you are subscribed to the Google Groups 
>> "Protocol Buffers" group.
>> To unsubscribe from this group and stop receiving emails from it, send an 
>> email to protobuf+u...@googlegroups.com .
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>> .
>> Visit this group at https://groups.google.com/group/protobuf.
>> For more options, visit https://groups.google.com/d/optout.
>>
>
>

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Re: [protobuf] How to erase particular field with MergeFrom()

['Feng Xiao' via Protocol Buffers]

On Wed, May 11, 2016 at 5:09 AM, Denis Bakhvalov 
wrote:

> Hi,
>
> Suppose I have such message structure:
>
>
> package msg_RepAndOpt;
>
> message RepAndOpt{
> repeated string name = 1;
> optional string surname = 2;
> ...
> // there are lots of others.}
>
>
> And I have two components that have copies of this message:
>
>
> // component1:RepAndOpt A;
> A.add_name("Name");
> A.set_surname("Surname");
> // component2:RepAndOpt B;
>
>
> In my case components modify those messages via transaction mechanism. It
> means that if one component changes some field it also sends it to another
> component to propagate those changes. Component-receiver is doing merge:
>
>
> // Component2 modifies B and sends it to component1.// Component1 perfoms 
> merge:
> A.MergeFrom(B);
>
>
> Now, say, component2 wants to erase field "name". If it will send clear B
> message (default construction) than:
>
>- - MergeFrom() will not modify A;
>- - CopyFrom() will erase also other fields.
>
> Another way will be to fill B with the contents of A, clear name field and
> component1 will use CopyFrom(). But this is not acceptable because system
> is really high-loaded and there could be lots of other fields. So, desired
> solution to clean name field is:
>
>1. 1. Component2 create B message.
>2. 2. Explicitly stores information that it want to erase only name
>field.
>3. 3. Component1 perform A.MergeFrom(B).
>4. 4. Result: A::name is cleared but other fields are left untouched.
>
> As far as I tested this applies to repeated and optional fields. Is there
> any ready-to-use solution or I should modify protobuf implementation?
>
I think you can do this using FieldMaskUtil:
https://github.com/google/protobuf/blob/beta-3/src/google/protobuf/util/field_mask_util.h#L111

You create an empty B message along with a FieldMask containing only the
field you want to clear, and use FieldMaskUtil::MergeMessageTo(A,
field_mask, )  to replace the field in A with the value from B.



> --
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[protobuf] How to erase particular field with MergeFrom()

[Denis Bakhvalov]

Hi,

Suppose I have such message structure:


package msg_RepAndOpt;

message RepAndOpt{
repeated string name = 1;
optional string surname = 2;
...
// there are lots of others.}


And I have two components that have copies of this message:


// component1:RepAndOpt A;
A.add_name("Name");
A.set_surname("Surname");
// component2:RepAndOpt B;


In my case components modify those messages via transaction mechanism. It 
means that if one component changes some field it also sends it to another 
component to propagate those changes. Component-receiver is doing merge:


// Component2 modifies B and sends it to component1.// Component1 perfoms merge:
A.MergeFrom(B);


Now, say, component2 wants to erase field "name". If it will send clear B 
message (default construction) than:

   - - MergeFrom() will not modify A;
   - - CopyFrom() will erase also other fields.

Another way will be to fill B with the contents of A, clear name field and 
component1 will use CopyFrom(). But this is not acceptable because system 
is really high-loaded and there could be lots of other fields. So, desired 
solution to clean name field is:

   1. 1. Component2 create B message.
   2. 2. Explicitly stores information that it want to erase only name 
   field.
   3. 3. Component1 perform A.MergeFrom(B).
   4. 4. Result: A::name is cleared but other fields are left untouched.

As far as I tested this applies to repeated and optional fields. Is there 
any ready-to-use solution or I should modify protobuf implementation?

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