Blob values in my table are added to the Solr document as object strings like B@1f23c5
The problem occurs because blobs are read as a byte array which does not have a useful toString method. The workaround is to:
Use convertType="true" on the JdbcDataSource
Write a Transformer which converts the byte into a string type
You can also use a "cast" sql function which can convert the data type from blob to strings if your database provides such a function
Note that "convertType" attribute uses the target schema field's type name to convert the value returned by the result set. Therefore, any transformers being used on the entity should be aware of the type information.