[
https://issues.apache.org/jira/browse/THRIFT-1964?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13862075#comment-13862075
]
Jens Geyer edited comment on THRIFT-1964 at 1/11/14 7:18 PM:
-------------------------------------------------------------
Hi [~xqgzh] and [~carlyeks],
{quote}
change the name of 'Isset' to 'ClassNameIssert', it's just a little change,
because there's only one reference to this typename inside the class. please
check fix_Isset_xmlserializer.patch
{quote}
A better (compatible) approach could be one of these
{code}
[XmlType(Namespace = "http://tempuri.org/Thrift.Test.A";)]
// or
[XmlType("Thrift_Test_A_Isset")]
{code}
but neither would solve the unset optionals issue. I have tried some things and
found, that the various serialization concepts used in C#/.NET are a really
PITA to deal with, because they overlap in some details and differ completely
in other.
h3. System.Xml.Serialization.XmlSerializer
The best way to deal with this flavour is to produce XML like the following (no
nullables here):
{code:xml}
<?xml version="1.0"?>
<C xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
xmlns:xsd="http://www.w3.org/2001/XMLSchema";>
<A>
<Message>test</Message>
<Zero>0</Zero>
</A>
<B>
<IsBool>true</IsBool>
<Message>test2</Message>
<A>
<Message>test3</Message>
<Zero>0</Zero>
</A>
</B>
</C>
{code}
The <Value_not_set> tag is omitted, because this value is not set. Thus, the
property is not touched during deserialization and so is the {{isset}} flag,
which is exactly what we want. To achieve this, we need two things: (1) the
{{XmlIgnore}} flag at the {{isset}} member variable, and (2) a bunch of
[ShouldSerialize*()
methods|http://msdn.microsoft.com/en-us/library/53b8022e(vs.71).aspx] telling
the serializer whether or not an optional field is to be serialized:
{code}
public bool ShouldSerializeMessage()
{
return __isset.message;
}
{code}
h3. DataContractJsonSerializer and related serializer classes
Unfortunately, the {{ShouldSerialize*()}} approach does not work here, so we
have to find another way. The single biggest issue with unset optionals is,
that even if the {{isset}} flags are serialized, they are read earlier, before
all the data members. That problem can be solved by means of the
{{DataMember(Order = <number>)}} attribute as [outlined over
here|http://msdn.microsoft.com/en-us/library/ms729813(v=vs.110).aspx].
After these changes we get some JSON as follows:
{code}
{
"A":{
"Message":"test",
"Value_not_set":0,
"Zero":0,
"__isset":{ "message":true, "value_not_set":false, "zero":true }
},
"B":{
"A":{
"Message":"test3",
"Value_not_set":0,
"Zero":0,
"__isset":{ "message":true, "value_not_set":false, "zero":true }
},
"IsBool":true,
"Message":"test2",
"__isset":{
"a":true,
"isBool":true,
"message":true
}
},
"__isset":{ "a":true, "b":true }
}
{code}
which does not follow the same structure as the XML above, but does what we
want.
h3. Tests
- sucessfully tested with C# 2010 for Desktop and for Windows Phone 7.x
- WCF and Mono not yet tested
h3. Files
- [^modified-testcase.zip]
- [^THRIFT-1964-serializer-vs-isset-v2.patch ] (was:
-[^THRIFT-1964-serializer-vs-isset.patch]-)
What do you think?
was (Author: jensg):
Hi [~xqgzh] and [~carlyeks],
{quote}
change the name of 'Isset' to 'ClassNameIssert', it's just a little change,
because there's only one reference to this typename inside the class. please
check fix_Isset_xmlserializer.patch
{quote}
A better (compatible) approach could be one of these
{code}
[XmlType(Namespace = "http://tempuri.org/Thrift.Test.A";)]
// or
[XmlType("Thrift_Test_A_Isset")]
{code}
but neither would solve the unset optionals issue. I have tried some things and
found, that the various serialization concepts used in C#/.NET are a really
PITA to deal with, because they overlap in some details and differ completely
in other.
h3. System.Xml.Serialization.XmlSerializer
The best way to deal with this flavour is to produce XML like the following (no
nullables here):
{code:xml}
<?xml version="1.0"?>
<C xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
xmlns:xsd="http://www.w3.org/2001/XMLSchema";>
<A>
<Message>test</Message>
<Zero>0</Zero>
</A>
<B>
<IsBool>true</IsBool>
<Message>test2</Message>
<A>
<Message>test3</Message>
<Zero>0</Zero>
</A>
</B>
</C>
{code}
The <Value_not_set> tag is omitted, because this value is not set. Thus, the
property is not touched during deserialization and so is the {{isset}} flag,
which is exactly what we want. To achieve this, we need two things: (1) the
{{XmlIgnore}} flag at the {{isset}} member variable, and (2) a bunch of
[ShouldSerialize*()
methods|http://msdn.microsoft.com/en-us/library/53b8022e(vs.71).aspx] telling
the serializer whether or not an optional field is to be serialized:
{code}
public bool ShouldSerializeMessage()
{
return __isset.message;
}
{code}
h3. DataContractJsonSerializer and related serializer classes
Unfortunately, the {{ShouldSerialize*()}} approach does not work here, so we
have to find another way. The single biggest issue with unset optionals is,
that even if the {{isset}} flags are serialized, they are read earlier, before
all the data members. That problem can be solved by means of the
{{DataMember(Order = <number>)}} attribute as [outlined over
here|http://msdn.microsoft.com/en-us/library/ms729813(v=vs.110).aspx].
After these changes we get some JSON as follows:
{code}
{
"A":{
"Message":"test",
"Value_not_set":0,
"Zero":0,
"__isset":{ "message":true, "value_not_set":false, "zero":true }
},
"B":{
"A":{
"Message":"test3",
"Value_not_set":0,
"Zero":0,
"__isset":{ "message":true, "value_not_set":false, "zero":true }
},
"IsBool":true,
"Message":"test2",
"__isset":{
"a":true,
"isBool":true,
"message":true
}
},
"__isset":{ "a":true, "b":true }
}
{code}
which does not follow the same structure as the XML above, but does what we
want.
h3. Tests
- sucessfully tested with C# 2010 for Desktop and for Windows Phone 7.x
- WCF and Mono not yet tested
h3. Files
- [^modified-testcase.zip]
- [^THRIFT-1964-serializer-vs-isset.patch]
What do you think?
> 'Isset' causes problems with C#/.NET serializers
> ------------------------------------------------
>
> Key: THRIFT-1964
> URL: https://issues.apache.org/jira/browse/THRIFT-1964
> Project: Thrift
> Issue Type: Bug
> Components: C# - Compiler
> Affects Versions: 0.9, 0.9.1
> Reporter: xq.gzh
> Assignee: Jens Geyer
> Labels: Isset, serializers
> Fix For: 0.9.2
>
> Attachments: 1964-v2.patch, 1964.patch, ReproduceTheIssue.zip,
> THRIFT-1964-serializer-vs-isset-v2.patch, a.thrift,
> fix_Isset_xmlserializer.patch, fix_isset_problem_test.zip,
> modified-testcase.zip
>
> Original Estimate: 8h
> Remaining Estimate: 8h
>
> same class name 'Isset' in user defined class will cause xmlserializer
> crashed.
> below is the sample thrift:
> struct A {
> 1: string x;
> }
> struct B {
> 1: string y;
> }
> struct C {
> 1:A a
> 2:B b
> }
> generate code and try xmlserialize instance of class C. it crashed.
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