The p:graphicImage uses another request so you need to pass an identifier to the managedBean like this.
<p:dataTable value="#{productManaged.products}" var="productIterated">
<p:column>
<f:facet name="header">
<h:outputText value="#{product.pic}"/>
</f:facet>
<p:graphicImage value="#{productManaged.dynamicProductImage}">
<f:param name="product_id" value="#{productIterated.id}"/>
</p:graphicImage>
</p:column>
</p:dataTable>
Another thing that you should take care is to return something in the StreamedContent or is gonna fail. Do something like this:
public StreamedContent getDynamicProductImage() {
String id = FacesContext.getCurrentInstance()
.getExternalContext().getRequestParameterMap().get("product_id");
if(id!=null && this.products!=null && !this.products.isEmpty()){
Integer productId = Integer.parseInt(id);
for(Product productTemp:this.products){
if(productTemp.getId().equals(productId)){
return new DefaultStreamedContent(
new ByteArrayInputStream(productTemp.getImage()),
productTemp.getMimeType());
}
}
}
return new DefaultStreamedContent(
new ByteArrayInputStream(this.products.get(0).getImage()),
this.products.get(0).getMimeType()); //if you return null here then it won't work!!! You have to return something.
}
or you can read this thread http://primefaces.prime.com.tr/forum/viewtopic.php?f=3&t=4163