[jira] [Created] (THRIFT-1976) Javascript client unable to serialize/deserialize maps with struct keys

["Andrew Stanton (JIRA)" <ji...@apache.org>]

Andrew Stanton created THRIFT-1976:
--------------------------------------

             Summary: Javascript client unable to serialize/deserialize maps with struct keys
                 Key: THRIFT-1976
                 URL: https://issues.apache.org/jira/browse/THRIFT-1976
             Project: Thrift
          Issue Type: Bug
          Components: JavaScript - Compiler, JavaScript - Library
    Affects Versions: 0.9
         Environment: All
            Reporter: Andrew Stanton


The Javascript compiler is unable to serialize maps where a struct is a key due to particularities with how Javascript treats {} objects.

Using the following thrift definition:

struct Foo {
    1: required string name;
}

struct Bar {
    1: required string description;
}

struct Mapper {
    1: required map<Foo,Bar> fooToBar;
}

/* End */

It produces the following javascript code:

/* Start -Snipped */

Mapper.prototype.write = function(output) {
  output.writeStructBegin('Mapper');
  if (this.fooToBar !== null && this.fooToBar !== undefined) {
    output.writeFieldBegin('fooToBar', Thrift.Type.MAP, 1); 
    output.writeMapBegin(Thrift.Type.STRUCT, Thrift.Type.STRUCT, Thrift.objectLength(this.fooToBar));
    // XXX
    // This will always fail as kiter8 will always be a String
    // XXX
    for (var kiter8 in this.fooToBar)
    {   
      if (this.fooToBar.hasOwnProperty(kiter8))
      {   
        var viter9 = this.fooToBar[kiter8];
        // kiter8 is a string, not an object.
        kiter8.write(output);
        viter9.write(output);
      }   
    }   
    output.writeMapEnd();
    output.writeFieldEnd();
  }
  output.writeFieldStop();
  output.writeStructEnd();
  return;
};
/* END */

This code always fails since enumeration of an object's keys will always yield String values.  I've annotated the relevant parts in the above code.

There isn't really a simple fix for this either: Using for-in, there is no way to get a reference to the original key object.  Practically, a Map type would have to be added to the thrift library with basic put()/get()/delete() operations to allow for struct maps.

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