在Apache Lucene中获取字段类型

Question

What I'm trying to achieve is a way to detect if the stored value is numeric( IntPoint or FloatPoint ) or string( StringField or TextField ).

For example : I'm storing this field

doc.add(new IntPoint("Value", 4));

after I execute a query that return some documents I want to detect if Value field type is IntPoint

I'm using something like this

IndexableField field = doc.getField("Value");
if (field != null)
    System.out.println(field.fieldType());

which returns stored

If I use field.fieldType().docValuesType() it will return NONE

Is there a way to achieve this?

Answer 1

This seems to be what Luke does, hope it helps

 public static String fieldFlags(Field fld, FieldInfo info) {
    ...
    Number numeric = null;
    if (fld == null) {
      ...
    } else {
      ...
      numeric = fld.numericValue();
    }
    ...
    if (numeric != null) {
      flags.append("#");
      // try faking it
      if (numeric instanceof Integer) {
        flags.append("i32");
      } else if (numeric instanceof Long) {
        flags.append("i64");
      } else if (numeric instanceof Float) {
        flags.append("f32");
      } else if (numeric instanceof Double) {
        flags.append("f64");
      } else if (numeric instanceof Short) {
        flags.append("i16");
      } else if (numeric instanceof Byte) {
        flags.append("i08");
      } else if (numeric instanceof BigDecimal) {
        flags.append("b^d");
      } else if (numeric instanceof BigInteger) {
        flags.append("b^i");
      } else {
        flags.append("???");
      }
      ...
    }

Link to luke code

Answer 2

First of all, here is remark about IntPoint field

An indexed field for fast range filters. If you also need to store the value, you should add a separate StoredField instance.

which basically means, I'm not sure, how you get this working:

IndexableField field = doc.getField("Value");

it should return you null , instead of a field. Also, applicable to all fields - if you're operating on Document returned to your by Lucene - it will only contains fields, which are stored once again.

For stored fields, you could easily get their type by doing something like this:

((StoredField) text).fieldsData

which would return exactly what's stored there - Float or String or Double.

Another possibility is to call set of methods stringValue, binaryValue, readerValue, numericValue , which would return you String , ByteRef , Reader or Number or null, if it's not a number, for example.