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https://issues.apache.org/jira/browse/CALCITE-6244?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17850780#comment-17850780
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Mihai Budiu commented on CALCITE-6244:
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As Julian said, you are supposed to use the same text for the JIRA issue, the
PR title, and usually the sole commit in the final PR. Then some automated jobs
can keep track of these links. For example, a bot would have added a link to
your PR in this JIRA issue.
> Improve `Expressions#constant` to allow Java records
> ----------------------------------------------------
>
> Key: CALCITE-6244
> URL: https://issues.apache.org/jira/browse/CALCITE-6244
> Project: Calcite
> Issue Type: Improvement
> Components: linq4j
> Reporter: Wegdan Ghazi
> Assignee: Wegdan Ghazi
> Priority: Minor
> Fix For: 1.38.0
>
>
> To use
> [Expressions#constant|https://github.com/apache/calcite/blob/e17098d47f3c31e4d90cc17e6e1da1175bf49ae4/linq4j/src/main/java/org/apache/calcite/linq4j/tree/Expressions.java#L540]
> with complex models, it's required to pass a model with public fields, as
> can be seen in this
> [test|https://github.com/apache/calcite/blob/e17098d47f3c31e4d90cc17e6e1da1175bf49ae4/linq4j/src/test/java/org/apache/calcite/linq4j/test/ExpressionTest.java#L865].
> i.e. to successfully pass an instance of `{{{}Employee{}}}`, it must be
> defined as follows:
> {code:java}
> public static class Employee {
> public final int empno;
> public final String name;
> public final int deptno; public Employee(int empno, String name, int
> deptno) {
> this.empno = empno;
> this.name = name;
> this.deptno = deptno;
> } public String toString() {
> return "Employee(name: " + name + ", deptno:" + deptno + ")";
> } @Override public int hashCode() {
> final int prime = 31;
> int result = 1;
> result = prime * result + deptno;
> result = prime * result + empno;
> result = prime * result + ((name == null) ? 0 : name.hashCode());
> return result;
> } @Override public boolean equals(Object obj) {
> if (this == obj) {
> return true;
> }
> if (obj == null) {
> return false;
> }
> if (getClass() != obj.getClass()) {
> return false;
> }
> Employee other = (Employee) obj;
> if (deptno != other.deptno) {
> return false;
> }
> if (empno != other.empno) {
> return false;
> }
> if (name == null) {
> if (other.name != null) {
> return false;
> }
> } else if (!name.equals(other.name)) {
> return false;
> }
> return true;
> }
> } {code}
> This makes it difficult to use generated classes e.g. Java records or
> immutables, or even encapsulated POJOs to pass through Linq4j.
> This is caused by the logic to
> [explore|https://github.com/apache/calcite/blob/e17098d47f3c31e4d90cc17e6e1da1175bf49ae4/linq4j/src/main/java/org/apache/calcite/linq4j/tree/ConstantExpression.java#L299]
> and
> [create|https://github.com/apache/calcite/blob/e17098d47f3c31e4d90cc17e6e1da1175bf49ae4/linq4j/src/main/java/org/apache/calcite/linq4j/tree/ConstantExpression.java#L216]
> the model constructor; which depends on:
> {code:java}
> value.getClass().getFields() {code}
> which only accesses public fields.
> {*}Proposed solution{*}: Access fields using reflection, by accessing their
> getter methods.
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