title: SolrException: Document [null] missing required field: id
body: <p>I have changed the schema.xml file and added few fields in that like this</p>
  
  <pre><code>&lt;field name="url" type="string" indexed="true" stored="true" /&gt;
     &lt;field name="content_type" type="text" indexed="true" stored="true" /&gt;
     &lt;field name="title" type="text" indexed="true" stored="true" /&gt;
     &lt;field name="keywords" type="text" indexed="true" stored="true" multiValued="true" /&gt;
     &lt;field name="text" type="text" indexed="true" stored="true" /&gt;
     &lt;field name="timestamp" type="text" indexed="true" stored="true" /&gt;
     &lt;field name="public" type="text" indexed="true" stored="true" multiValued="true" /&gt;
     &lt;field name="groups" type="text" indexed="true" stored="true" multiValued="true" /&gt;
     &lt;field name="sitename" type="text" indexed="true" stored="true" /&gt;
     &lt;field name="context" type="text" indexed="true" stored="true" /&gt;
     &lt;field name="modified_date" type="text" indexed="true" stored="true" /&gt;
  </code></pre>
  
  <p>so corresponding to these fields I have created one xml file and added some dummy data into that like this.</p>
  
  <pre><code>    &lt;add&gt;&lt;doc&gt;
    &lt;field name="url"&gt;http://www.host.com/&lt;/field&gt;
    &lt;field name="content_type"&gt;text/html&lt;/field&gt;
    &lt;field name="title"&gt;Testing Data&lt;/field&gt;
    &lt;field name="keywords"&gt;software&lt;/field&gt;
    &lt;field name="keywords"&gt;software_cycle&lt;/field&gt;
    &lt;field name="text"&gt;search&lt;/field&gt;
    &lt;field name="timestamp"&gt;2006-02-13T15:26:37Z&lt;/field&gt;
    &lt;field name="public"&gt;Optimized&lt;/field&gt;
    &lt;field name="public"&gt;Optimized_data&lt;/field&gt;
    &lt;field name="groups"&gt;Standards&lt;/field&gt;
    &lt;field name="groups"&gt;Standards_data&lt;/field&gt;
    &lt;field name="sitename"&gt;GoInfo&lt;/field&gt;
    &lt;field name="context"&gt;Scalability&lt;/field&gt;
    &lt;field name="modified_date"&gt;2010-11-13T15:26:37Z&lt;/field&gt;
    &lt;/doc&gt;&lt;/add&gt;
  </code></pre>
  
  <p>And when I tried to reindex the data into solr like this:-</p>
  
  <pre><code>C:\apache-solr-3.2.0\example\exampledocs&gt;java -Durl=http://localhost:7788/solr/u
  pdate -jar post.jar *.xml
  SimplePostTool: version 1.3
  SimplePostTool: POSTing files to http://localhost:7788/solr/update..
  SimplePostTool: POSTing file 30-example.xml
  SimplePostTool: POSTing file hd.xml
  SimplePostTool: POSTing file other.xml
  SimplePostTool: FATAL: Solr returned an error #400 Bad Request
  </code></pre>
  
  <p>I always get an error after text.xml file and If I remove this text.xml file then I don't get any error.. This is the below error I am getting if I include the text.xml file. Any help will be appreciated.</p>
  
  <pre><code>SEVERE: org.apache.solr.common.SolrException: Document [null] missing required field: id
          at org.apache.solr.update.DocumentBuilder.toDocument(DocumentBuilder.java:336)
          at org.apache.solr.update.processor.RunUpdateProcessor.processAdd(RunUpdateProcessorFactory.java:60)
          at org.apache.solr.handler.XMLLoader.processUpdate(XMLLoader.java:147)
          at org.apache.solr.handler.XMLLoader.load(XMLLoader.java:77)
          at org.apache.solr.handler.ContentStreamHandlerBase.handleRequestBody(ContentStreamHandlerBase.java:67)
          at org.apache.solr.handler.RequestHandlerBase.handleRequest(RequestHandlerBase.java:129)
          at org.apache.solr.core.SolrCore.execute(SolrCore.java:1360)
          at org.apache.solr.servlet.SolrDispatchFilter.execute(SolrDispatchFilter.java:356)
          at org.apache.solr.servlet.SolrDispatchFilter.doFilter(SolrDispatchFilter.java:252)
          at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
          at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
          at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
          at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
          at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
          at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
          at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
          at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
          at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:864)
          at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:579)
          at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:1665)
          at java.lang.Thread.run(Thread.java:662)
  </code></pre>