Add multiple order by capability

Author: TimothyGillespie

src/main/java/org/javawebstack/orm/query/Query.java

@@ -24,8 +24,7 @@ public class Query<T extends Model> {
     private final QueryGroup<T> where;
     private Integer offset;
     private Integer limit;
-    private QueryColumn order;
-    private boolean desc = false;
+    private QueryOrderBy order;
     private boolean withDeleted = false;
     private final List<QueryWith> withs = new ArrayList<>();
 
@@ -37,6 +36,7 @@ public Query(Repo<T> repo, Class<T> model) {
         this.repo = repo;
         this.model = model;
         this.where = new QueryGroup<>();
+        this.order = new QueryOrderBy();
     }
 
     public boolean isWithDeleted() {
@@ -59,14 +59,10 @@ public Integer getOffset() {
         return offset;
     }
 
-    public QueryColumn getOrder() {
+    public QueryOrderBy getOrder() {
         return order;
     }
 
-    public boolean isDescOrder() {
-        return desc;
-    }
-
     public Repo<T> getRepo() {
         return repo;
     }
@@ -300,18 +296,25 @@ public Query<T> search(String search) {
         return this;
     }
 
+    public Query<T> order(String orderBy) {
+        return order(orderBy, false);
+    }
+
     public Query<T> order(String orderBy, boolean desc) {
         return order(new QueryColumn(orderBy), desc);
     }
 
     public Query<T> order(QueryColumn orderBy, boolean desc) {
-        this.order = orderBy;
-        this.desc = desc;
-        return this;
-    }
+        boolean success = this.order.add(orderBy, desc);
+        if(!success) {
+            throw new ORMQueryException(String.format(
+                "The column %s could not be ordered %s. This is probably caused by calling .order() on this column twice.",
+                orderBy.toString(),
+                desc ? "descendingly" : "ascendingly"
+            ));
+        }
 
-    public Query<T> order(String orderBy) {
-        return order(orderBy, false);
+        return this;
     }
 
     public Query<T> limit(int offset, int limit) {

src/main/java/org/javawebstack/orm/query/QueryOrderBy.java

@@ -0,0 +1,28 @@
+package org.javawebstack.orm.query;
+
+import java.util.LinkedList;
+import java.util.List;
+
+public class QueryOrderBy extends LinkedList<QueryOrderByElement>{
+
+    public boolean add(String columnName, boolean desc) {
+        return this.add(new QueryColumn(columnName), desc);
+    }
+
+    public boolean add(QueryColumn column, boolean desc) {
+        return this.add(new QueryOrderByElement(column, desc));
+    }
+
+    @Override
+    public boolean add(QueryOrderByElement element) {
+        boolean hasBeenAdded = false;
+        if(!willOverwrite(element))
+            hasBeenAdded = super.add(element);
+
+        return hasBeenAdded;
+    }
+
+    private boolean willOverwrite(QueryOrderByElement element) {
+        return this.stream().anyMatch(element::hasEqualColumn);
+    }
+}

src/main/java/org/javawebstack/orm/query/QueryOrderByElement.java

@@ -0,0 +1,53 @@
+package org.javawebstack.orm.query;
+
+import java.util.Objects;
+
+public class QueryOrderByElement {
+    private QueryColumn queryColumn;
+    private boolean desc;
+
+    QueryOrderByElement(String columnName, boolean desc) {
+        queryColumn = new QueryColumn(columnName);
+        this.desc = desc;
+    }
+
+    QueryOrderByElement(QueryColumn column, boolean desc) {
+        this.queryColumn = column;
+        this.desc = desc;
+    }
+
+    public QueryColumn getQueryColumn() {
+        return queryColumn;
+    }
+
+    public boolean isDesc() {
+        return desc;
+    }
+
+    public boolean hasEqualColumn(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        QueryOrderByElement that = (QueryOrderByElement) o;
+        return getQueryColumn().equals(that.getQueryColumn());
+    }
+
+    public boolean hasEqualOrderDirection(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        QueryOrderByElement that = (QueryOrderByElement) o;
+        return isDesc() == that.isDesc();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        QueryOrderByElement that = (QueryOrderByElement) o;
+        return isDesc() == that.isDesc() && getQueryColumn().equals(that.getQueryColumn());
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(getQueryColumn(), isDesc());
+    }
+}