How best to process dynamic query parameters using Java & Spring - sql

Question

The problem:
I have an api endpoint which handles multiple query parameters. It is implemented using Spring, and the query parameters are used to query data from a postgres database, which I query with a JDBC Template.
I am searching for a mature query builder technology to solve my problem.
Example:
A trivial query could look something like this:
api/book?name=LOTR&cover=hardback
The query parameters are added to a map, and a query string is build from the maps data:
String sqlQuery += (String) map.entrySet().stream()
.map(entry -> entry.getKey() + "='" + entry.getValue() + "' AND ")
.collect(Collectors.joining());
Its not the most efficient, as I must always remove the trailing "AND" clause from the string, but it works.
However, if the query where to look something like
api/book?name=LOTR&name=Ulysses&cover=hardback
there is now the addition of an "OR" clause, which the above code would not handle. I can see myself quickly getting into the territory of with tedious string parsing to create SQL statements.
So now that I have presented my problem, I wonder if there is a technology I can use which handles this kind of problem nicely?
I would like to avoid the use of any ORM for this project, so Hibernate and MyBatis are out of the question. I have looked at some JOOQ examples, but they do not look compatible with JDBC Template.

Answer 1

For trivial implementations like your first case where you have to remove last AND after your query is built there is a simple hack - immediately after WHERE you add 1 = 1 and then for every WHERE predicate you add AND [COLUMN] = [VALUE].
Note: most databases optimise use of constants in WHERE clause before execution, so performance will not be an issue
/*
select <columns> from <tables> where 1 = 1
[dynamically built Where predicates will come here from following code]
*/
String sqlQuery += (String) map.entrySet().stream()
.map(entry -> "AND " + entry.getKey() + "='" + entry.getValue() + "'")
.collect(Collectors.joining());
However for serious production implementations you may want to use frameworks like myBatis that gives you possibilities of templating a query and then passing parameters at runtime to build final queries.
You can find a good tutorial here.
/* An example */
<select id = "getName_Id_phone" parameterType = "Student" resultType = "Student">
SELECT * FROM STUDENT
<where>
<if test = "id != null">
id = #{id}
</if>
<if test = "name != null">
AND name LIKE #{name}
</if>
</where>
</select>

Answer 2

Came across here with the same question. Maybe you want to take a look at RSQL 1