Search the Library

public List<Book__c> searchBooks(String searchTerm) {
    List<List<sObject>> searchResults = [
        FIND :searchTerm IN ALL FIELDS
        RETURNING Book__c(Id, Title__c, Author__c, Is_Checked_Out__c)
    ];

    return (List<Book__c>) searchResults[0];
}

1. public List<Book__c> searchBooks(String searchTerm) { — this is Module 21's SOSL search pattern, applied directly.
2. List<List<sObject>> searchResults = [ — opens the search.
3. FIND :searchTerm IN ALL FIELDS — matches the term against Title__c, Author__c, and any other searchable text field on Book__c at once.
4. RETURNING Book__c(Id, Title__c, Author__c, Is_Checked_Out__c) — one object, the fields to return.
5. ]; — closes the search.
6. (blank line)
7. return (List<Book__c>) searchResults[0]; — casts the first inner list back to a specific type, one search covering both title and author lookups a user might type.
8. } — closes the method.

LibraryService library = new LibraryService();
List<Book__c> results = library.searchBooks('Bachman');

for (Book__c book : results) {
    System.debug(book.Title__c + ' by ' + book.Author__c);
}

1. LibraryService library = new LibraryService(); — creates the service.
2. List<Book__c> results = library.searchBooks('Bachman'); — a member typing "Bachman" into a search box finds every book by that author — even though the search term matched Author__c, not Title__c.
3. (blank line)
4. for (Book__c book : results) { — loops over the matches.
5. System.debug(book.Title__c + ' by ' + book.Author__c); — the search code never needed to know in advance which field the match would come from.
6. } — closes the loop.

// The SOQL alternative would need two separate queries and merged results
List<Book__c> byTitle = [SELECT Id, Title__c FROM Book__c WHERE Title__c LIKE :('%' + searchTerm + '%')];
List<Book__c> byAuthor = [SELECT Id, Title__c FROM Book__c WHERE Author__c LIKE :('%' + searchTerm + '%')];
// ...then manually merge and deduplicate the two lists

1. // The SOQL alternative would need two separate queries and merged results — the label for the comparison.
2. List<Book__c> byTitle = [SELECT Id, Title__c FROM Book__c WHERE Title__c LIKE :('%' + searchTerm + '%')]; — one query, matching only the title.
3. List<Book__c> byAuthor = [SELECT Id, Title__c FROM Book__c WHERE Author__c LIKE :('%' + searchTerm + '%')]; — a second query, matching only the author.
4. // ...then manually merge and deduplicate the two lists — the extra work a SOQL-only approach would require, that SOSL avoids entirely.