SOLR-18187: Document enrichment with LLMs by nicolo-rinaldi · Pull Request #4259 · apache/solr

nicolo-rinaldi · 2026-04-01T16:11:45Z

https://issues.apache.org/jira/browse/SOLR-18187

Description

The goal of this PR is to add a way to integrate LLMs directly into Solr at index time to fill fields that might be useful (e.g., categories, tags, etc.)

Solution

This PR adds LLM-based document enrichment capabilities to Solr's indexing pipeline via a new DocumentEnrichmentUpdateProcessorFactory in the language-models module. The processor allows users to enrich documents at index time by calling an LLM (via https://github.com/langchain4j/langchain4j) with a configurable prompt built from one or more existing document fields (inputFields), and storing the model's response into an output field. The output field can be of different types (i.e., string, text, int, long, float, double, boolean, and date) and can be single-valued or multi-valued. The structured output has been used to adapt to the output field type.

The implementation has taken inspiration from the text-to-vector feature in the same module. This has been done to keep the implementation consistent with conventions already in the language-models module.

Note: this PR was developed with assistance from Claude Code (Anthropic).

Tests

Tests covering configuration validation (missing required params, conflicting params, invalid field types, placeholder mismatches), and processor initialization.

Tests covering single-valued and multi-valued output fields of all supported types, multi-input-field prompts, prompt file loading, error handling (model exceptions, ambiguous/malformed JSON responses, unsupported model types), and skipNullOrMissingFieldValues behaviour. All the supported models have been tested.

Checklist

Please review the following and check all that apply:

I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
I have created a Jira issue and added the issue ID to my pull request title.
I have given Solr maintainers access to contribute to my PR branch. (optional but recommended, not available for branches on forks living under an organisation)
I have developed this patch against the main branch.
I have run ./gradlew check.
I have added tests for my changes.
I have added documentation for the Reference Guide
I have added a changelog entry for my change

…tUpdateProcessorFactory

- multivalued outputField - outputField different from Str/Text, with numeric, boolean and date

…or documentation

…t with LLMs' module

…rFactory

aruggero

Left some comments

aruggero · 2026-04-13T08:17:31Z

+    restTestHarness.delete(ManagedChatModelStore.REST_END_POINT + "/model1");
+  }
+
+  private UpdateRequestProcessor createUpdateProcessor(


Can't this always be generalised and used for all the tests? In some of them, you are now repeating this code with small changes...

this is the same as createUpdateProcessor a part from the creation of the request and getInstance()
maybe we can exclude the solr request + getInstance() and use that method also here? calling it like "initializeUpdateProcessorFactory"?
what do you think?

I created a function initializeUpdateProcessorFactory that is used inside createUpdateProcessor. In this way, the code inside the first one can be reused

Fixed tests

why some test could not use these new functions?
e.g. init_multipleInputFields_shouldInitAllFields

I kept them unrelated to the model creation, just to see the proper initialization of the Factory. I can see if this can be changed if you want

aruggero · 2026-04-13T13:57:46Z

+    restTestHarness.delete(ManagedChatModelStore.REST_END_POINT + "/model1");
+  }
+
+  private UpdateRequestProcessor createUpdateProcessor(


this is the same as createUpdateProcessor a part from the creation of the request and getInstance()
maybe we can exclude the solr request + getInstance() and use that method also here? calling it like "initializeUpdateProcessorFactory"?
what do you think?

…fields and updated documentation

nicolo-rinaldi · 2026-04-15T13:27:05Z

+
+=== Models
+
+* A model in this module is a chat model, that answers with text given a prompt.


nicolo-rinaldi · 2026-04-15T13:27:12Z

+=== Models
+
+* A model in this module is a chat model, that answers with text given a prompt.
+* A model in this Solr module is a reference to an external API that runs the Large Language Model responsible for chat


nicolo-rinaldi · 2026-04-15T13:30:38Z

+
+Exactly one of the following parameters is required: `prompt` or `promptFile`.
+
+Another important feature of this module is that one (or more) `inputField` needs to be injected in the prompt. This is


…orks

alessandrobenedetti · 2026-04-17T14:47:58Z

+            .messages(UserMessage.from(prompt))
+            .build();
+    String rawJson = chatModel.chat(chatRequest).aiMessage().text();
+    Object parsed = Utils.fromJSONString(rawJson);


Is parsing an 'Object' necessary?

alessandrobenedetti · 2026-04-17T14:51:04Z

+  public SolrChatModel getModel(String modelName) {
+    return store.getModel(modelName);
+  }
+


this entire class feels like exactly the same of the one I implemented for embedding models.
Can't we use the same class but for multiple storage solutions?
So you instantiate different endpoints but same class.
It feels a lot of duplicate code

alessandrobenedetti · 2026-04-17T14:51:37Z

+          "model '" + name + "' already exists. Please use a different name");
+    }
+  }
+}


see above in regards of duplicated code

alessandrobenedetti · 2026-04-17T14:53:42Z

+      // as for now, only a plain text as prompt is sent to the model (no support for
+      // tools/skills/agents)
+      // chatModel.chat returns the parsed value from the structured JSON response
+      Object value = chatModel.chat(injectedPrompt, responseFormat);


value? isn't it the output? Also, langchain4j returns an 'Object'? is that a weak typing?

alessandrobenedetti · 2026-04-17T14:56:46Z

+    String injectedPrompt = prompt;
+    for (String fieldName : inputFields) {
+      SolrInputField field = doc.get(fieldName);
+      if (isNullOrEmpty(field)) {


if a field is null you skip enrichment for the entire document? It's suspicious, we should discuss what it means to have multiple fields in input.
My assumption would be you define a processor for a list of fields, to enrich each of them in the same way.
having a null field should only skip the field rather than the full document?

alessandrobenedetti · 2026-04-17T14:58:27Z

+ *   <li>Exactly one of {@code prompt} or {@code promptFile} must be provided.
+ *   <li>Every declared {@code inputField} must have a corresponding {@code {fieldName}} placeholder
+ *       in the prompt.
+ *   <li>Every {@code {placeholder}} in the prompt must correspond to a declared {@code inputField}.


this huge comment is unreadable code-wise and suspicious, probably it should be improved

nicolo-rinaldi added 11 commits March 25, 2026 13:06

[llm-document-erichment] Add first revision of the feature

b11d049

[llm-document-enrichment] First working version

dfb27ab

[llm-document-enrichment] Add promptFile feature to DocumentEnrichmen…

827548a

…tUpdateProcessorFactory

[llm-document-enrichment] Add multiple inputField support + tests

cc94317

[llm-document-enrchment] Add supprot for:

c723362

- multivalued outputField - outputField different from Str/Text, with numeric, boolean and date

[llm-document-enrichment] polished code, added tests and added file f…

cf0d6bb

…or documentation

[llm-document-enrichment] updated supported models + added tests

570c2aa

[llm-document-enrichment] added documentation for 'Document Enrichmen…

184f579

…t with LLMs' module

[llm-document-enrichment] cleanup of DocumentEnrichmentUpdateProcesso…

1b7c972

…rFactory

Merge branch 'main' into llm-document-enrichment

9cf0315

Merge branch 'main' into llm-document-enrichment

36208af

github-actions bot added documentation Improvements or additions to documentation dependencies Dependency upgrades tool:build tests labels Apr 1, 2026

aruggero suggested changes Apr 3, 2026

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aruggero suggested changes Apr 13, 2026

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[llm-document-enrichment] Addressed comments in Anna's review

3d29d16

aruggero suggested changes Apr 13, 2026

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nicolo-rinaldi added 2 commits April 13, 2026 17:55

[llm-document-enrichment] Addressed comments in Anna's review

55ff9ab

[llm-document-enrichment] Fixed broken tests and updated documentation

ed40008

aruggero suggested changes Apr 15, 2026

View reviewed changes

[llm-document-enrichment] Added tests, Exception for multiple output …

ba27be1

…fields and updated documentation

nicolo-rinaldi commented Apr 15, 2026

View reviewed changes

aruggero suggested changes Apr 15, 2026

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nicolo-rinaldi added 2 commits April 15, 2026 17:22

[llm-document-enrichment] Updated documentation

b092f22

Merge branch 'main' into llm-document-enrichment

6e9525d

nicolo-rinaldi requested a review from aruggero April 17, 2026 08:29

aruggero approved these changes Apr 17, 2026

View reviewed changes

nicolo-rinaldi added 3 commits April 17, 2026 11:18

[llm-document-enrichment] Pre-check changes

4f39e40

Merge branch 'main' into llm-document-enrichment

b2b51a6

[llm-document-enrichment] Post-check changes. Now ./gradlew check w…

af48a10

…orks

alessandrobenedetti reviewed Apr 17, 2026

View reviewed changes

[llm-document-enrichment] Fix GitHub actions failures

f15285e


		=== Models

		* A model in this module is a chat model, that answers with text given a prompt.


		Exactly one of the following parameters is required: `prompt` or `promptFile`.

		Another important feature of this module is that one (or more) `inputField` needs to be injected in the prompt. This is

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Description

Solution

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Checklist

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nicolo-rinaldi commented Apr 1, 2026 •

edited

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alessandrobenedetti Apr 17, 2026 •

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