FirstFieldValueUpdateProcessorFactory (Solr 7.7.0 API)

java.lang.Object
- org.apache.solr.update.processor.UpdateRequestProcessorFactory
- - org.apache.solr.update.processor.FieldMutatingUpdateProcessorFactory
  - - org.apache.solr.update.processor.FieldValueSubsetUpdateProcessorFactory
    - - org.apache.solr.update.processor.FirstFieldValueUpdateProcessorFactory

All Implemented Interfaces:

NamedListInitializedPlugin, SolrCoreAware
```
public final class FirstFieldValueUpdateProcessorFactory
extends FieldValueSubsetUpdateProcessorFactory
```
Keeps only the first value of fields matching the specified conditions. Correct behavior assumes that the SolrInputFields being mutated are either single valued, or use an ordered Collection (ie: not a Set).
By default, this processor matches no fields.

For example, in the configuration below, if a field named primary_author contained multiple values (ie: "Adam Doe", "Bob Smith", "Carla Jones") then only the first value (ie: "Adam Doe") will be kept
```
 <processor class="solr.FirstFieldValueUpdateProcessorFactory">
   <str name="fieldName">primary_author</str>
 </processor>
 
```
Since:

4.0.0

See Also:

LastFieldValueUpdateProcessorFactory

Nested Class Summary
- Nested classes/interfaces inherited from class org.apache.solr.update.processor.FieldMutatingUpdateProcessorFactory
  FieldMutatingUpdateProcessorFactory.SelectorParams
- Nested classes/interfaces inherited from class org.apache.solr.update.processor.UpdateRequestProcessorFactory
  UpdateRequestProcessorFactory.RunAlways

Constructor Summary

Constructors
Constructor Description

FirstFieldValueUpdateProcessorFactory()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`FieldMutatingUpdateProcessor.FieldNameSelector`	`getDefaultSelector(SolrCore core)`	Defines the default selection behavior when the user has not configured any specific criteria for selecting fields.
`Collection<Object>`	`pickSubset(Collection<Object> values)`	Method subclasses must override to specify which values should be kept.

Methods inherited from class org.apache.solr.update.processor.FieldValueSubsetUpdateProcessorFactory
getInstance

Methods inherited from class org.apache.solr.update.processor.FieldMutatingUpdateProcessorFactory
getSelector, inform, init, parseSelectorExclusionParams, parseSelectorParams

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - FirstFieldValueUpdateProcessorFactory
```
public FirstFieldValueUpdateProcessorFactory()
```
- Method Detail
  - pickSubset
```
public Collection<Object> pickSubset(Collection<Object> values)
```
    Description copied from class: FieldValueSubsetUpdateProcessorFactory
    
    Method subclasses must override to specify which values should be kept. This method will not be called unless the collection contains more then one value.
    
    Specified by:
    
    pickSubset in class FieldValueSubsetUpdateProcessorFactory
  - getDefaultSelector
```
public FieldMutatingUpdateProcessor.FieldNameSelector getDefaultSelector(SolrCore core)
```
    Description copied from class: FieldMutatingUpdateProcessorFactory
    
    Defines the default selection behavior when the user has not configured any specific criteria for selecting fields. The Default implementation matches all fields, and should be overridden by subclasses as needed.
    
    Overrides:
    
    getDefaultSelector in class FieldMutatingUpdateProcessorFactory
    
    See Also:
    
    FieldMutatingUpdateProcessor.SELECT_ALL_FIELDS