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https://issues.apache.org/jira/browse/AVRO-680?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14088027#comment-14088027
]
Sachin Goyal commented on AVRO-680:
-----------------------------------
I am not sure how to find that the given map has non-string map-keys in isMap()
and isArray() functions.
This is because the type information of a parameterized map-object is lost due
to type-erasure.
Consider the following code:
{code}
import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.util.Map;
import java.util.HashMap;
public class NonStringMapTest
{
public static void main (String args[]) throws Exception
{
NSMFoo obj = new NSMFoo();
Field field = obj.getClass().getDeclaredFields()[0];
Class<?> type = field.getType();
ParameterizedType pt = (ParameterizedType)field.getGenericType();
Object map = field.get(obj);
System.out.println ("Field: " + field);
System.out.println ("Type: " + type);
System.out.println ("GenericType (Field): " + pt);
System.out.println ("Class (Datum): " + map.getClass());
}
}
class NSMFoo
{
Map <NSMKey, String> map = new HashMap<NSMKey, String>();
}
class NSMKey
{
int i;
}
{code}
And the output from it is:
{code}
Field: java.util.Map reflection.NSMFoo.map
Type: interface java.util.Map
GenericType (Field): java.util.Map<reflection.NSMKey, java.lang.String>
Class (Datum): class java.util.HashMap
{code}
The isMap and isArray functions are receiving just the datum and no Field
object.
If there is a way to deduce that the given map datum has non-string keys, then
I can add that logic in those functions.
I don't think passing the Field object all the way to isArray and isMap would
be good.
What do you think?
> Allow for non-string keys
> -------------------------
>
> Key: AVRO-680
> URL: https://issues.apache.org/jira/browse/AVRO-680
> Project: Avro
> Issue Type: Improvement
> Affects Versions: 1.7.6, 1.7.7
> Reporter: Jeremy Hanna
> Attachments: AVRO-680.patch, non_string_map_keys.zip,
> non_string_map_keys2.zip, non_string_map_keys3.zip,
> non_string_map_keys4.patch, non_string_map_keys5.patch
>
>
> Based on an email thread back in April, Doug Cutting proposed a possible
> solution for having non-string keys:
> Stu Hood wrote:
> > I can understand the reasoning behind AVRO-9, but now I need to look for an
> > alternative to a 'map' that will allow me to store an association of bytes
> > keys to values.
> A map of Foo has the same binary format as an array of records, each
> with a string field and a Foo field. So an application can use an array
> schema similar to this to represent map-like structures with, e.g.,
> non-string keys.
> Perhaps we could establish standard properties that indicate that a
> given array of records should be represented in a map-like way if
> possible? E.g.,:
> {"type": "array", "isMap": true, "items": {"type":"record", ...}}
> Doug
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