Yeah, I can see how that is misleading (though it does not mention "required" fields -- it claims all fields). It should say "Get an instance of the type with no fields set. Because no fields are set, all getters for singular fields will return default values and repeated fields will appear empty.".
On Mon, Mar 22, 2010 at 4:56 PM, Kevin Tambascio <[email protected]>wrote: > Kenton, > > This description in the MessageLite documentation is what led me to > believe the default values would be there. I figured I was > misinterpreting the documentation, or the meaning behind the default > value: > > getDefaultInstanceForType > > MessageLite getDefaultInstanceForType() > Get an instance of the type with all fields set to their default > values. This may or may not be a singleton. This differs from the > getDefaultInstance() method of generated message classes in that this > method is an abstract method of the MessageLite interface whereas > getDefaultInstance() is a static method of a specific class. They > return the same thing. > > http://code.google.com/apis/protocolbuffers/docs/reference/java/index.html > > Thanks for your help, > Kevin > > > On Mar 22, 7:07 pm, Kenton Varda <[email protected]> wrote: > > "required" means "If this field is not explicitly set before build() is > > called, or if parseFrom() parses a message missing this field, throw an > > exception.". It does NOT mean "Automatically fill in this field.". > Please > > point me at any documentation which suggests the latter meaning so I can > fix > > it. > > > > The default value is the value returned by the field's getter when the > field > > has not been explicitly assigned any other value. > > > > getAllFields() only returns field which have been explicitly set. > > > > On Mon, Mar 22, 2010 at 2:42 PM, Kevin Tambascio > > <[email protected]>wrote: > > > > > > > > > Kenton, > > > > > I did make some more progress today, along the lines of what you said > > > below. I'm seeing an issue where calling > > > DynamicMessage.getDefaultInstance(type) is not filling in the default > > > values. This is with 2.3.0 of GPB. > > > > > My proto file: > > > > > message StringTableEntry > > > { > > > required string lang = 1 [default = "en-US"]; > > > required string value = 2 [default = ""]; > > > } > > > > > When I instantiate an instance of StringTableEntry, using > > > DynamicMessage, the required fields are not in the message instance. > > > From reading the documentation, it sounds like the default values > > > should show up if I create an object. My code for creation is this: > > > > > FileDescriptor fd = > > > FileDescriptor.buildFrom(fdSet.getFile(0), fds); > > > List<Descriptor> messageTypes = fd.getMessageTypes(); > > > for(Descriptor type : messageTypes) > > > { > > > DynamicMessage dm = > > > DynamicMessage.newBuilder(type).getDefaultInstanceForType(); > > > > > //DynamicMessage dm = > > > DynamicMessage.getDefaultInstance(type); > > > > > Map<FieldDescriptor, Object> dmFields = > > > dm.getAllFields(); > > > for(Entry<FieldDescriptor, Object> entry : > > > dmFields.entrySet()) > > > { > > > System.out.println("default value for > this > > > field: " + > > > entry.getValue().toString()); > > > entry.setValue("Data"); > > > } > > > > > System.out.println(XmlFormat.printToString(dm)); > > > } > > > > > When instantiating the object, using either the commented or > > > uncommented out lines of code above, fails to contain the required > > > fields with their default values. If I poke around the 'type' > > > variable in the debugger, I can see that the 2 fields are in the > > > descriptor, and the default values are there as well. But the > > > instance of the message does not contain those two fields > > > (dmFields.entrySet() returns null, and the code inside the > > > "for(Entry<FieldDescriptor, Object> entry : dmFields.entrySet())" loop > > > does not execute). > > > > > It seems like I could write a routine to set the default values based > > > on the Descriptor data, but I think that getDefaultInstance should do > > > that for me. > > > > > Thoughts? > > > > > Thanks, > > > Kevin > > > > > On Mar 22, 4:02 pm, Kenton Varda <[email protected]> wrote: > > > > DescriptorProto.getDescriptorForType() returns the Descriptor for > > > > DescriptorProto, not for the type which that DescriptorProto is > > > describing. > > > > Remember that DescriptorProto is just a protocol message like any > other > > > -- > > > > it does not have any special methods that recognize its higher-level > > > > meaning. > > > > > > To convert DescriptorProtos to Descriptors, you need to use > > > > FileDescriptor.buildFrom(). > > > > > > On Sun, Mar 21, 2010 at 5:20 PM, Kevin Tambascio > > > > <[email protected]>wrote: > > > > > > > Hi, > > > > > > > I'm having trouble getting the following code to work. Using > > > > > protoc.exe, I generated a file with the descriptor data using the > -- > > > > > descriptor_set_out file. I've written some Java code to read the > > > > > file, and try to instantiate a default instance of one of the > objects > > > > > in the descriptor, so that I write it out to an XML file using the > > > > > protobuf-format-java library. > > > > > > > Here's my code. The variable "descriptorData" contains the binary > > > > > content of the descriptor file, without any modifications: > > > > > > > DescriptorProtos.FileDescriptorSet fdSet = > > > > > FileDescriptorSet.newBuilder().mergeFrom(descriptorData).build(); > > > > > FileDescriptorProto fdp = fdSet.getFile(0); > > > > > > > List<DescriptorProto> messageTypes = > > > > > fdp.getMessageTypeList(); > > > > > for(DescriptorProto type : messageTypes) > > > > > { > > > > > System.out.println("Type is: " + > > > type.getName()); > > > > > FileDescriptor fd = > > > > > type.getDescriptorForType().getFile(); > > > > > > > DynamicMessage dm = > > > > > DynamicMessage.getDefaultInstance(type.getDescriptorForType()); > > > > > > System.out.println(XmlFormat.printToString(dm)); > > > > > } > > > > > > > I've tried numerous combinations of the above code, but each time I > > > > > get the following output: > > > > > > > Type is: Type1 > > > > > <DescriptorProto></DescriptorProto> > > > > > Type is: Type2 > > > > > <DescriptorProto></DescriptorProto> > > > > > Type is: Type3 > > > > > <DescriptorProto></DescriptorProto> > > > > > Type is: Type4 > > > > > <DescriptorProto></DescriptorProto> > > > > > Type is: Type5 > > > > > <DescriptorProto></DescriptorProto> > > > > > Type is: Type6 > > > > > <DescriptorProto></DescriptorProto> > > > > > > > The proto file has Type1, Type2, Type3, etc, defined as messages. > The > > > > > fact that type.getName() does return the type names from my proto > > > > > file, leads me to believe I'm heading in the right direction. > > > > > However, the DynamicMessage type that is created (and serialized to > > > > > XML) seems to indicate that I'm not passing the right descriptor > > > > > instance in to create the object. > > > > > > > Any thoughts? > > > > > > > Thanks, > > > > > Kevin > > > > > > > -- > > > > > You received this message because you are subscribed to the Google > > > Groups > > > > > "Protocol Buffers" group. > > > > > To post to this group, send email to [email protected]. > > > > > To unsubscribe from this group, send email to > > > > > [email protected]<protobuf%[email protected]> > <protobuf%[email protected] om> > > > <protobuf%[email protected] om> > > > > > . > > > > > For more options, visit this group at > > > > >http://groups.google.com/group/protobuf?hl=en. > > > > > -- > > > You received this message because you are subscribed to the Google > Groups > > > "Protocol Buffers" group. > > > To post to this group, send email to [email protected]. > > > To unsubscribe from this group, send email to > > > [email protected]<protobuf%[email protected]> > <protobuf%[email protected] om> > > > . > > > For more options, visit this group at > > >http://groups.google.com/group/protobuf?hl=en. > > -- > You received this message because you are subscribed to the Google Groups > "Protocol Buffers" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<protobuf%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/protobuf?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Protocol Buffers" group. 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