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POMap<String, String> with JPA
 

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  1. POMap<String, String> with JPA
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    <p>I have JPA entity like this:</p> <pre><code>@Entity @Table(name = "ATTRIBUTE") public class Attribute { //ID stuff @Column(name = "NAME", nullable = false) private String name; @Column(name = "VALUE", nullable = false) private String value; //getters and setters } </code></pre> <p>And the other entity:</p> <pre><code>@Entity @Table(name = "ATTRIBUTE_GROUP") public class AttributeGroup { //ID stuff @ElementCollection(fetch = FetchType.LAZY, targetClass = java.lang.String.class) @CollectionTable(name = "ATTRIBUTE") @MapKeyColumn(name = "NAME") @Column(name = "VALUE") private Map&lt;String, String&gt; attributes = new HashMap&lt;&gt;(); public void createAttribute(String name, String value) { Attribute attribute = new Attribute(); attribute.setName(name); attribute.setValue(value); attribute.setAttributeGroup(this); attributes.put(name, value); } public Map&lt;String, String&gt; getAttributes() { return attributes; } } </code></pre> <p>I need to have a map in <code>AttributeGroup</code> entity which will have <code>Attribute</code>'s name as a key and <code>Attribute</code>'s value as a value.</p> <p>The current approach does not work for me. When I am trying to persist records to the database it generates exception that transaction is marked as roolback only. I don't know if it is even the write way to do this, well if it is not working obviously it is not.</p> <p>How can I achieve this in JPA to have a map in <code>AttributeGroup</code> made from <code>Attribute</code> name/value paired object?</p> <p>I am using Hibernate via EntityManager.</p>
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    1. USuser2219247
    1. USuser2219247
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    1. COis it compulsory to use hibernate annotations? can't we go for xml mapping?
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      1. POMap<String, String> with JPA
      1. USRuchira Gayan Ranaweera
    2. COYes it is, I need to stick to JPA approach, hibernate is just an implementation, as we might be migrating to OpenJPA in future.
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      1. USuser2219247
    3. COPost the complete stack trace of the exception, and the code causing it. Also, what's the point of the Attribute entity? You don't seem to use it. You create a new Attribute in your method but don't do anything with it.
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      1. POMap<String, String> with JPA
      1. USJB Nizet
 

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