org.dellroad.querystream.jpa.ParamBinding Maven / Gradle / Ivy

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/*
 * Copyright (C) 2018 Archie L. Cobbs. All rights reserved.
 */

package org.dellroad.querystream.jpa;

import java.util.Objects;

import javax.persistence.Parameter;
import javax.persistence.Query;

/**
 * Represents the binding of a value to a {@link Parameter}.
 *
 * @see Query#setParameter(javax.persistence.Parameter, Object)
 */
public class ParamBinding {

    private final Parameter parameter;
    private final T value;

    /**
     * Constructor.
     *
     * @param parameter the parameter to set
     * @param value parameter value
     * @throws IllegalArgumentException if {@code parameter} is null
     */
    public ParamBinding(final Parameter parameter, final T value) {
        if (parameter == null)
            throw new IllegalArgumentException("null parameter");
        this.parameter = parameter;
        this.value = value;
    }

    /**
     * Get the parameter.
     *
     * @return parameter to be bound
     */
    public Parameter getParameter() {
        return this.parameter;
    }

    /**
     * Get the parameter value.
     *
     * @return value to be bound to parameter
     */
    public T getValue() {
        return this.value;
    }

    /**
     * Apply this parameter binding to the given query.
     *
     * @param query the query to configure
     * @throws IllegalArgumentException if {@code query} is null
     */
    public void applyTo(Query query) {
        if (query == null)
            throw new IllegalArgumentException("null query");
        this.doApplyTo(query);
    }

    void doApplyTo(Query query) {
        query.setParameter(this.getParameter(), this.getValue());
    }

// Object

    @Override
    public boolean equals(Object obj) {
        if (obj == this)
            return true;
        if (obj == null || obj.getClass() != this.getClass())
            return false;
        final ParamBinding that = (ParamBinding)obj;
        return this.parameter.equals(that.parameter) && Objects.equals(this.value, that.value);
    }

    @Override
    public int hashCode() {
        return this.parameter.hashCode() ^ Objects.hashCode(this.value);
    }

    @Override
    public String toString() {
        return this.getClass().getSimpleName()
          + "[parameter=" + ParamBinding.describeParameter(this.parameter)
          + ",value=" + this.value
          + "]";
    }

    static String describeParameter(Parameter parameter) {
        String result = "parameter \"" + parameter.getName() + "\"";
        try {
            result += " of type " + parameter.getParameterType().getSimpleName();
        } catch (IllegalStateException | NullPointerException e) {
            // ignore
        }
        return result;
    }
}