alter the logic of left/right-join, make it more intuitive (see the docs)

Author: mhewedy

README.md

@@ -63,7 +63,7 @@ For spring-boot 3.x:
 <dependency>
   <groupId>com.github.mhewedy</groupId>
   <artifactId>spring-data-jpa-mongodb-expressions</artifactId>
-  <version>0.1.6</version>
+  <version>0.1.7</version>
 </dependency>
 
 ```

docs/include.adoc

@@ -1,5 +1,5 @@
 :author: Mohammad Hewedy, The Spring Data JPA MongoDB Expressions Team
-:revnumber: 0.1.6
+:revnumber: 0.1.7
 :jsondir: ../src/test/resources
 :sectlinks: true
 :source-highlighter: highlight.js

docs/query_specs.adoc

@@ -308,13 +308,13 @@ Generated SQL:
 +
 NOTE: The `distinct` keyword is being used in the queries to eliminate duplicates in case of `one-to-many` and `many-to-many` joins.
 
-TIP: Sometimes the join capabilities is not enough or the not best way for the use case you trying to implement,
+TIP: Sometimes the join capabilities is not enough or not the best way for the use case you trying to implement,
 in such case you can create a database _view_ and map it to an JPA Entity and then build your search on it.
 
 TIP: The returned properties are the properties of the primary Entity, which means the `projection` is not supported due to limitation in spring-data-jpa addressed in this https://github.com/mhewedy/spring-data-jpa-mongodb-expressions/issues/4[bug,role=external,window=_blank], until it is fixed and if you need to return properties from other entities involved in the join, you need to follow the database _view_ workaround mentioned in the previous tip.
 
 ==== Left and right joins
-1. Left join uses notation `.<` and right join uses `.>`, exmaple on left join:
+1. Left join uses notation `.<` and right join uses `.>`, example on left join (department left join city):
 +
 [source,json]
 ----
@@ -324,12 +324,12 @@ Generated SQL:
 +
 [source,sql]
 ----
-...from employee e left join department d on d.id=e.department_id join city c on c.id=d.city_id where e.first_name=? or c.name=?
+...from employee e join department d on d.id = e.department_id left join city c on c.id = d.city_id where e.first_name = ? or c.name = ?
 ----
 +
 NOTE: The join notation that define the relation between an object and its association so,
-`department.<city.name` means left join between `employee` (current object) and `department`,
-where `department.city.<name` means left join between `departement` and `city`
+`"<department.city.name"` means left join between `employee` (current object) and `department`,
+where `"department.<city.name"` means left join between `departement` and `city`
 
 === Embedded
 1. Using embedded fields:

pom.xml

@@ -12,7 +12,7 @@
 
     <groupId>com.github.mhewedy</groupId>
     <artifactId>spring-data-jpa-mongodb-expressions</artifactId>
-    <version>0.1.6</version>
+    <version>0.1.7</version>
     <name>spring-data-jpa-mongodb-expressions</name>
     <description>Spring Data JPA Mongodb Expressions</description>
 

src/main/java/com/github/mhewedy/expressions/ExpressionsPredicateBuilder.java

@@ -119,7 +119,7 @@ private static List<Predicate> getPredicates(CriteriaQuery<?> query, CriteriaBui
                             predicate = cb.greaterThan(exprPath, (Comparable) attributeValue);
                         } else {
                             throw new IllegalArgumentException("field should be Number or Comparable: " +
-                                                               singularExpression);
+                                    singularExpression);
                         }
                         break;
                     case $gte:
@@ -129,7 +129,7 @@ private static List<Predicate> getPredicates(CriteriaQuery<?> query, CriteriaBui
                             predicate = cb.greaterThanOrEqualTo(exprPath, (Comparable) attributeValue);
                         } else {
                             throw new IllegalArgumentException("field should be Number or Comparable: " +
-                                                               singularExpression);
+                                    singularExpression);
                         }
                         break;
                     case $lt:
@@ -139,7 +139,7 @@ private static List<Predicate> getPredicates(CriteriaQuery<?> query, CriteriaBui
                             predicate = cb.lessThan(exprPath, (Comparable) attributeValue);
                         } else {
                             throw new IllegalArgumentException("field should be Number or Comparable: " +
-                                                               singularExpression);
+                                    singularExpression);
                         }
                         break;
                     case $lte:
@@ -149,7 +149,7 @@ private static List<Predicate> getPredicates(CriteriaQuery<?> query, CriteriaBui
                             predicate = cb.lessThanOrEqualTo(exprPath, (Comparable) attributeValue);
                         } else {
                             throw new IllegalArgumentException("field should be Number or Comparable: " +
-                                                               singularExpression);
+                                    singularExpression);
                         }
                         break;
                     // like
@@ -258,7 +258,7 @@ private static List<Predicate> getPredicates(CriteriaQuery<?> query, CriteriaBui
             throw new IllegalArgumentException(
                     String.format(
                             "Unable to locate attribute with the given name [%s] on this ManagedType [%s]," +
-                            " Are you sure this ManagedType or one of its ancestors contains such attribute?",
+                                    " Are you sure this ManagedType or one of its ancestors contains such attribute?",
                             field,
                             type.getJavaType().getName()
                     )
@@ -280,22 +280,17 @@ private static ManagedType<?> extractSubFieldType(Attribute<?, ?> attribute) {
     }
 
     private static String extractField(String field) {
-        return field.contains(".") ? field.split("\\.")[0] : field;
+        return field.contains(".") ? field.split("\\.")[0].replaceAll("^[<>]+", "") : field;
     }
 
     private static SubField extractSubField(String field) {
-        //if field is "abc.efg.xyz", then return "efg.xyz", so to support n-level association
+        //if field is "abc.efg.xyz", then mainField=>"abc" and subField => "efg.xyz", so to support n-level association
+        String mainField = Arrays.stream(field.split("\\.")).limit(1).collect(Collectors.joining("."));
         String subField = Arrays.stream(field.split("\\.")).skip(1).collect(Collectors.joining("."));
-        JoinType joinType;
-        if (subField.startsWith("<")) { /// .<
-            subField = subField.substring(1);
-            joinType = JoinType.LEFT;
-        } else if (subField.startsWith(">")) {  ///  .>
-            subField = subField.substring(1);
-            joinType = JoinType.RIGHT;
-        } else {
-            joinType = JoinType.INNER;
-        }
+
+        JoinType joinType = mainField.startsWith("<") ? JoinType.LEFT // <abc
+                : mainField.startsWith(">") ? JoinType.RIGHT // >abc
+                : JoinType.INNER;   //// abc
         return new SubField(subField, joinType);
     }