How to store user sql where clause, and how to apply it on a select? - postgresql

Question

I am using JPA / Eclipselink / PostgreSQL within my application.
I have a model that list some data, and I would like to let the user of the application to create his own where clause parameters.
How can I store theses parameters ? as plain sql string ?
Then how can I apply the where clause ? as a simple string concatenation ? (I don't like this idea at all).
Bests regards.

Answer 1

Ok, so I solved my problem.
For information : I have created a recursive JSON representation of every where clause parameters possibility.
And I have created a query using criteria api by decoding the pojo structure from json.
The json class look like that :
public class JSonSearchCriteria
{
public static enum CriteriaType
{
asc,
desc,
count,
countDistinct,
and,
or,
not,
equal,
notEqual,
between,
gt,
ge,
lt,
le,
like,
notLike;
}
#Expose
public CriteriaType type;
#Expose
public List<JSonSearchCriteria> sub;
#Expose
public String what = null;
#Expose
public List<Integer> integerValue = null;
#Expose
public List<Long> longValue = null;
#Expose
public List<Boolean> booleanValue = null;
#Expose
public List<String> stringValue = null;
#Expose
public List<DateTime> datetimeValue = null;
public JSonSearchCriteria()
{
}
public JSonSearchCriteria(final CriteriaType type)
{
this.type = type;
}
public JSonSearchCriteria(final CriteriaType type, final String what)
{
this(type);
this.what = what;
}
public JSonSearchCriteria(final CriteriaType type, final String what, final String... values)
{
this(type, what);
for(final String value : values)
{
value(value);
}
}
public JSonSearchCriteria(final CriteriaType type, final String what, final Long... values)
{
this(type, what);
for(final Long value : values)
{
value(value);
}
}
public JSonSearchCriteria(final CriteriaType type, final String what, final Integer... values)
{
this(type, what);
for(final Integer value : values)
{
value(value);
}
}
public JSonSearchCriteria(final CriteriaType type, final String what, final DateTime... values)
{
this(type, what);
for(final DateTime value : values)
{
value(value);
}
}
public void add(final JSonSearchCriteria subCriteria)
{
if(sub == null)
{
sub = new ArrayList<>();
}
sub.add(subCriteria);
}
public void value(final String value)
{
if(stringValue == null)
{
stringValue = new ArrayList<>();
}
stringValue.add(value);
}
public void value(final Long value)
{
if(longValue == null)
{
longValue = new ArrayList<>();
}
longValue.add(value);
}
public void value(final Integer value)
{
if(integerValue == null)
{
integerValue = new ArrayList<>();
}
integerValue.add(value);
}
public void value(final DateTime value)
{
if(datetimeValue == null)
{
datetimeValue = new ArrayList<>();
}
datetimeValue.add(value);
}
#SuppressWarnings(
{
"unchecked", "rawtypes"
})
#Transient
public Predicate buildPredicate(final CriteriaBuilder builder, final Root<Record> root, Join<Record, RecordInfo> infos)
{
switch(type)
{
case and:
case or:
final Predicate[] preds = new Predicate[sub.size()];
int cpt = 0;
for(final JSonSearchCriteria s : sub)
{
preds[cpt] = s.buildPredicate(builder, root, infos);
cpt++;
}
if(type == CriteriaType.and)
{
return builder.and(preds);
}
else if(type == CriteriaType.or)
{
return builder.or(preds);
}
break;
case equal:
case lt:
case gt:
case between:
final Path p;
if(what.startsWith("infos."))
{
p = infos.get(what.substring(6));
}
else
{
p = root.get(what);
}
if(stringValue != null && !stringValue.isEmpty())
{
if(type == CriteriaType.equal)
{
return builder.equal(p, stringValue.get(0));
}
}
else if(longValue != null && !longValue.isEmpty())
{
if(type == CriteriaType.equal)
{
return builder.equal(p, longValue.get(0));
}
else if(type == CriteriaType.lt)
{
return builder.lt(p, longValue.get(0));
}
else if(type == CriteriaType.gt)
{
return builder.gt(p, longValue.get(0));
}
}
else if(integerValue != null && !integerValue.isEmpty())
{
if(type == CriteriaType.equal)
{
return builder.equal(p, integerValue.get(0));
}
else if(type == CriteriaType.lt)
{
return builder.lt(p, integerValue.get(0));
}
else if(type == CriteriaType.gt)
{
return builder.gt(p, integerValue.get(0));
}
}
else if(booleanValue != null && !booleanValue.isEmpty())
{
return builder.equal(p, booleanValue.get(0));
}
else if(datetimeValue != null && !datetimeValue.isEmpty())
{
if(type == CriteriaType.equal)
{
return builder.equal(p, datetimeValue.get(0));
}
else if(type == CriteriaType.between && datetimeValue.size() > 1)
{
return builder.between(p, datetimeValue.get(0), datetimeValue.get(1));
}
}
break;
}
System.err.println(type + " - not implemented");
return null;
}
}
And it is used like that :
final SearchTemplate templ = DBHelper.get(SearchTemplate.class, 100);
final Gson gson = new GsonBuilder().registerTypeAdapter(DateTime.class, new DateTimeJsonAdapter()).create();
final JSonSearchCriteria crits = gson.fromJson(templ.getTemplate(), JSonSearchCriteria.class);
final CriteriaBuilder critBuilder = DBHelper.getInstance().em().getCriteriaBuilder();
final CriteriaQuery<Record> critQuery = critBuilder.createQuery(Record.class);
final Root<Record> root = critQuery.from(Record.class);
final Join<Record, RecordInfo> infos = root.join("infos");
critQuery.where(crits.buildPredicate(critBuilder, root, infos));
final TypedQuery<Record> query = DBHelper.getInstance().em().createQuery(critQuery);
final List<Record> result = query.getResultList();
for(final Record rec : result)
{
System.err.println(rec.toString());
}