To implement the MongoDB results pagination in Java, there are few parameters that need to be collected:<\/p>\n
1) the order of results (ascending \/ descending)
\n2) the field used to order the results
\n3) the number of element and the page selected
\n4) the field and the value used to filter the results<\/p>\n
As well as the results of query, the method needs to return the total number of elements. All returned elements will be saved in a HashMap.<\/p>\n
HashMap<String, Object> resultMap = new HashMap<String, Object>();\r\n\r\nDirection direction = Sort.DEFAULT_DIRECTION;\r\nif (sortDirection > 0) {\r\n\tdirection = Sort.Direction.ASC;\r\n} else { \r\n\tdirection = Sort.Direction.DESC;\r\n}\r\n\r\nList<\/pre>\nIf a pagination is required, skip<\/b> and limit<\/b> are used<\/p>\n\r\nif (pageSize > 0) {\r\n\tquery.skip((pageNum - 1 ) * pageSize);\r\n\tquery.limit(pageSize);\r\n}\r\n\r\nif ( sortField != null && !sortField.equals(\"\") ) {\t\t\t\t\r\n\tquery.with(new Sort(direction, sortField));\r\n}\r\n\r\nresults = mongoTemplate.find(query, Object.class);<\/pre>\nIf a pagination is required, queryCounter<\/b> (basically a version of query without pagination an limit) is used to calculate the total number of results. Of course, if pagination is not required, is possible to use directly the size of results.<\/p>\nif ( pageSize > 0 ) {\r\n\tresultMap.put(\"RESULT_SIZE\", (int) mongoTemplate.count(queryCounter, Object.class));\r\n} else {\r\n\t\/\/ If pagination is not required, the query is not re-executed\r\n\tresultMap.put(\"RESULT_SIZE\", results.size());\r\n}<\/pre>\nmongoTemplate is a spring bean defined in this way on context configuration:<\/p>\n
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