I have a list of roles in a database. They are of the form
application.Role1.read
application.Role1.write
application.Role2.read
application.Role3.read
So each role has an entry based on read/write permission. I want to convert the roles into a POJO which I can then send as JSON to a UI. Each POJO would have the role name, and a boolean for read or write permission.
Here is the RolePermission class:
import com.fasterxml.jackson.annotation.JsonInclude;
@JsonInclude(JsonInclude.Include.NON_NULL)
public class RolePermission {
private String roleName;
private boolean readAllowed;
private boolean writeAllowed;
public String getRoleName() {
return roleName;
}
public RolePermission setRoleName(String roleName) {
this.roleName = roleName;
return this;
}
public boolean isReadAllowed() {
return readAllowed;
}
public RolePermission setReadAllowed(boolean readAllowed) {
this.readAllowed = readAllowed;
return this;
}
public boolean isWriteAllowed() {
return writeAllowed;
}
public RolePermission setWriteAllowed(boolean writeAllowed) {
this.writeAllowed = writeAllowed;
return this;
}
}
I am doing the transformation like so:
public static final String ROLE_PREFIX = "application.";
public static final String ROLE_READ_PERMISSION = "read";
public static final String ROLE_WRITE_PERMISSION = "write";
@Override
public List<RolePermission> getRoles(Backend backend) {
List<String> allRoles = backend.getRoles()
.stream()
.map(s -> s.replace(ROLE_PREFIX, ""))
.sorted()
.collect(Collectors.toList());
Map<String, RolePermission> roleMap = new HashMap<>();
for (String role : allRoles) {
String[] tokens = role.split(".");
String roleName = tokens[0];
String permission = tokens[1];
if (!roleMap.containsKey(roleName))
roleMap.put(roleName, new RolePermission().setRoleName(roleName));
RolePermission permission = roleMap.get(roleName);
if (ROLE_READ_PERMISSION.equals(permission))
permission.setReadAllowed(true);
if (ROLE_WRITE_PERMISSION.equals(permission))
permission.setWriteAllowed(true);
}
return new LinkedList<>(roleMap.values());
}
Is there a way to do the foreach loop above using Java 8 streams?
This is a mock Backend instance that just returns a list of roles:
public class Backend {
public List<String> getRoles() {
return Arrays.asList(
"application.Role1.read",
"application.Role1.write",
"application.Role2.read",
"application.Role3.read"
);
}
}
You can use groupingBy
to join the different permissions for the same roleName together.
public static final String ROLE_PREFIX = "application.";
public static final String ROLE_READ_PERMISSION = "read";
public static final String ROLE_WRITE_PERMISSION = "write";
@Override
public List<RolePermission> getRoles(Backend backend) {
Map<String, List<String[]>> allRoles = backend.getRoles()
.stream()
.map(s -> s.replace(ROLE_PREFIX, "")) // something like "Role1.read"
.map(s -> s.split("\\.")) // something like ["Role1", "read"]
.collect(Collectors.groupingBy(split -> split[0]));
return allRoles.values()
.stream()
.map(this::buildPermission)
.collect(Collectors.toList());
}
private RolePermission buildPermission(List<String[]> roleEntries) {
RolePermission permission = new RolePermission().setRoleName(roleEntries.get(0)[0]);
roleEntries.stream()
.forEach(entry -> {
if (ROLE_READ_PERMISSION.equals(entry[1]))
permission.setReadAllowed(true);
if (ROLE_WRITE_PERMISSION.equals(entry[1]))
permission.setWriteAllowed(true);
});
return permission;
}
I also think that your String.split
was using an incorrect regex in the original post, because .
is a special regex character. I've tested this and it works correctly.
Output:
[RolePermission(roleName=Role3, readAllowed=true, writeAllowed=false),
RolePermission(roleName=Role2, readAllowed=true, writeAllowed=false),
RolePermission(roleName=Role1, readAllowed=true, writeAllowed=true)]
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