Solr data import: concatenating several comma-separated fields

Question

I am working on making a book catalog searchable using Solr. I have written a query that gets all of the info that I am interested in using DataImportHandler. Every book may have multiple formats, and each format has its own ISBN, format name, and price, which are expressed as comma-separated values, as follows:

|  id  |   title   |    isbns     |    prices     |  formats  |
|-------------------------------------------------------------|
|  1   |  A Book   | isbn1,isbn2  | price1,price2 | fmt1,fmt2 |
|  2   |  Another  |    anisbn    |     aprice    |  aformat  |
 ... ... ...

I am currently using a RegexTransformer and splitBy so that I can make isbns, prices, and formats multiValued fields for faceting. HOWEVER, I would ideally like to be able to pull out the values individually and store them in another field in the index. In other words, for the book with the Id 1 in the example, I would like to store the following fields as strings:

Field 1: "fmt1 (isbn1): price1"

Field 2: "fmt2 (isbn2): price2"

Is this sort of thing possible with Solr? I could always pull out the fields and process them on the application side, but since this Solr index will have multiple clients performing queries, I would rather store the extra values at the time I build the index.

Answer 1

It's all explained in DIH wiki, simply use groupNames param to specify field names (groups are regular regex groups).

EDIT:

groupNames : A comma separated list of field column names, used where the regex contains groups and each group is to be saved to a different field. If some groups are not to be named leave a space between commas.

In this example the attributes 'regex' and 'sourceColName' are custom attributes used by the transformer. It reads the field 'full_name' from the resultset and transforms it to two new target fields 'firstName' and 'lastName'. So even though the query returned only one column 'full_name' in the resultset the solr document gets two extra fields 'firstName' and 'lastName' which are 'derived' fields. These new fields are only created if the regexp matches.