如何在REST API中实现过滤

Question

I am building a restful api's using spring mvc and spring jpa for database connection. I have requirement to create a get api which can filter the results based on filterString(passed as query parameter to GET request).

Example GET api for filter employee objects is

http://localhost:8080/api/v1/employee?filter="(firstName eq john) and (lastName eq doe) or (empId eq 123)"

Currently I am achieving this by parse the filterString using regX and create the "spring jpa Specification" object from it

Below is the code snippet

public List<Employee> searchEmployee(String filter) throws Exception {
        // filter = "/"(firstName eq john) and (lastName eq doe) or (empId eq 123)/""
        // remove the " characters from start and end
        filter = filter.replaceAll("^\"|\"$", "");

        // spit the string basis of and/or
        String[] value = filter.split("(((?<=or)|(?=or)))|(((?<=and)|(?=and)))");
        Specification specs = null;
        String op = null;
        for (String f : value) {
            if (!"or".equalsIgnoreCase(f) && !"and".equalsIgnoreCase(f)) {
                String[] p = f.trim().split("\\s{1,}");
                if (p != null && p.length == 3) {
                    EmployeeSpecification es = new EmployeeSpecification(new SearchCriteria(p[0], p[1], p[2]));
                    if (specs == null ) {
                        specs = Specification.where(es);
                    } else {
                        if ("or".equalsIgnoreCase(op)) {
                            specs = specs.or(es);
                        } else if ("or".equalsIgnoreCase(op)) {
                            specs = specs.and(es);
                        }
                    }

                } else {
                    throw new Exception("Invalid search criteria");
                }

            } else {
                op = f;
            }


           List<Employee> l = empDao.findAll(specs);

          return l;

        }

I have seen many REST api's which support the filtering like this. Can anyone suggest what is the best way to implement filtering on RESt server side?

Answer 1

I use rsql-parser in my projects. I parse the query string creating the criteria object or the sql query.