Welcome back to our blog, code enthusiasts! Today, we’re going to tackle a fascinating and sometimes frustrating topic that may occur when executing a Native Query from a Spring Boot application. Let’s roll up our sleeves and decode the message “org.postgresql.util.PSQLException: ERROR: operator does not exist: integer = bytea.”
This error could be quite the head-scratcher, especially if you’re using JPA with PostgreSQL. It’s crucial to understand it, know why it happens, and learn how to resolve it. So let’s break it down, step by step, to understand the workings behind the scenes.
Diving Into the Problem
First, let’s look at a case scenario to understand the problem better. The error often manifests when trying to execute the following code:
javaCopy code
@NamedNativeQuery(
name = "getStudentSubjectsAssessment",
query = "SELECT subject.subject_title, j as assessment FROM assessment s JOIN LATERAL jsonb_array_elements(s.assessment) j(elem) ON (j.elem->>'student_id') = :student_id JOIN subject ON subject.id = s.subject_id WHERE s.subject_id IN (:subjects) AND s.academy_year_id = :academy_year_id AND s.term_id = :term_id AND s.section_id = :section_id",
resultSetMapping = "StudentAssessmentValue"
)
Surprisingly, when removing the part of the query WHERE s.subject_id IN (:subjects) or hardcoding the subjects’ values like s.subject_id IN (2,3,4), the code runs successfully. But if the value is coming from the request, the notorious error shows its face.
Decoding the Error
So what does the error “org.postgresql.util.PSQLException: ERROR: operator does not exist: integer = bytea” mean? Here’s the deal: it’s PostgreSQL’s way of saying that there is a data type mismatch.
In simpler terms, it tells us that the JDBC driver is passing the parameter to PostgreSQL as a byte array, but the target column is an integer type. That’s like trying to fit a square peg in a round hole!
Finding a Solution
After experiencing such a snag, we came across two efficient solutions. Let’s dive into them one by one:
Solution 1: TypedParameterValue
The first solution entails using TypedParameterValue for integer parameters. TypedParameterValue allows the application to specify not only a parameter value but also the Hibernate type descriptor. It’s the perfect tool for our predicament.
code
Query query = entityManager.createNativeQuery(sqlString, StudentAssessmentDTO.class);
query.setParameter("subjects", subjects);
query.setParameter("academy_year_id", new TypedParameterValue(IntegerType.INSTANCE, academy_year_id));
query.setParameter("term_id", new TypedParameterValue(IntegerType.INSTANCE, term_id));
query.setParameter("section_id", new TypedParameterValue(IntegerType.INSTANCE, section_id));
List<StudentAssessmentDTO> = query.getResultList();
In this approach, TypedParameterValue ensures that Hibernate passes the correct type information to the PostgreSQL JDBC driver.
Solution 2: Building In-Search Parameter String
The second approach involves creating a method that generates an IN search parameter string “(a,b,c)” and appending it to the query string. This solution works best when the element array size doesn’t grow rapidly.
code
public String generateInSearchParameter(Integer[]
inputArr){
StringBuilder search = new StringBuilder("(");
IntStream.range(0, inputArr.length).forEach(i -> {
if (i != inputArr.length - 1) {
search.append(inputArr[i]
).append(',');
} else {
search.append(inputArr[i]
);
}
});
search.append(")");
return search.toString();
}
Remember, it’s always good to have multiple solutions up your sleeve. Coding can sometimes be a trial and error process, and the more tools you have in your toolbox, the better!
Final Thoughts
Our journey into understanding and resolving the PSQLException has come to an end. We hope this tutorial was informative and helped bring some clarity to your coding endeavors. Remember, every error is a stepping stone towards becoming a better coder. Keep exploring, keep learning, and most importantly, keep coding
