content: /**
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.solr.schema;
  
  import org.apache.lucene.search.SortField;
  import org.apache.lucene.document.Fieldable;
  import org.apache.solr.search.function.ValueSource;
  import org.apache.solr.search.function.FileFloatSource;
  import org.apache.solr.search.QParser;
  import org.apache.solr.response.TextResponseWriter;
  import org.apache.solr.response.XMLWriter;
  import org.apache.solr.common.SolrException;
  
  import java.util.Map;
  import java.io.IOException;
  
  /** Get values from an external file instead of the index.
   *
   * <p/><code>keyField</code> will normally be the unique key field, but it doesn't have to be.
   * <ul><li> It's OK to have a keyField value that can't be found in the index</li>
   * <li>It's OK to have some documents without a keyField in the file (defVal is used as the default)</li>
   * <li>It's OK for a keyField value to point to multiple documents (no uniqueness requirement)</li>
   * </ul>
   * <code>valType</code> is a reference to another fieldType to define the value type of this field (must currently be FloatField (float))
   *
   * The format of the external file is simply newline separated keyFieldValue=floatValue.
   * <br/>Example:
   * <br/><code>doc33=1.414</code>
   * <br/><code>doc34=3.14159</code>
   * <br/><code>doc40=42</code>
   *
   * <p/>Solr looks for the external file in the index directory under the name of
   * external_&lt;fieldname&gt; or external_&lt;fieldname&gt;.*
   *
   * <p/>If any files of the latter pattern appear, the last (after being sorted by name) will be used and previous versions will be deleted.
   * This is to help support systems where one may not be able to overwrite a file (like Windows, if the file is in use).
   * <p/>If the external file has already been loaded, and it is changed, those changes will not be visible until a commit has been done.
   * <p/>The external file may be sorted or unsorted by the key field, but it will be substantially slower (untested) if it isn't sorted.
   * <p/>Fields of this type may currently only be used as a ValueSource in a FunctionQuery.
   *
   * @version $Id: ExternalFileField.java 1065312 2011-01-30 16:08:25Z rmuir $
   */
  public class ExternalFileField extends FieldType {
    private FieldType ftype;
    private String keyFieldName;
    private IndexSchema schema;
    private float defVal;
  
    @Override
    protected void init(IndexSchema schema, Map<String,String> args) {
      restrictProps(SORT_MISSING_FIRST | SORT_MISSING_LAST);
      String ftypeS = getArg("valType", args);
      if (ftypeS!=null) {
        ftype = schema.getFieldTypes().get(ftypeS);
        if (ftype==null || !(ftype instanceof FloatField)) {
          throw new SolrException(SolrException.ErrorCode.SERVER_ERROR, "Only float (FloatField) is currently supported as external field type.  got " + ftypeS);
        }
      }   
      keyFieldName = args.remove("keyField");
      String defValS = args.remove("defVal");
      defVal = defValS==null ? 0 : Float.parseFloat(defValS);
      this.schema = schema;
    }
  
    @Override
    public void write(XMLWriter xmlWriter, String name, Fieldable f) throws IOException {
      throw new UnsupportedOperationException();
    }
  
    @Override
    public void write(TextResponseWriter writer, String name, Fieldable f) throws IOException {
      throw new UnsupportedOperationException();
    }
  
    @Override
    public SortField getSortField(SchemaField field,boolean reverse) {
      throw new UnsupportedOperationException();
    }
  
    @Override
    public ValueSource getValueSource(SchemaField field, QParser parser) {
      // default key field to unique key
      SchemaField keyField = keyFieldName==null ? schema.getUniqueKeyField() : schema.getField(keyFieldName);
      return new FileFloatSource(field, keyField, defVal, parser);
    }
  
  
  }
  