MDO - Mongo data objects

MDO is a java code generator to create immutable data objects with enhancements for supporting mongo db.

The generated code includes builders and copy support of the objects.

Features:

• Small easy to read data declarations.
• Support immutable programming.
• Auto code generation.
• Builder for the object type.
• Copy to builder for creating modified versions.
• Index declaration.
• Mongo field name support for reduced field names in the database to save storage.
• Inner enums and inner data objects.

Installing

Note that mdo is written in go, so go will need to be installed.

Install the command line tool

go install github.com/samlotti/mongo_data_object

or if cloning the repository

go install mdo.go

Running

In the root directory of your java project, or the root of where your mongo entities will reside. Type

mdo

This will search the current directory and child directories for files ending in .mdo

It will read the mdo file and create java files of the same name in the same directory.

mdo -help

mdo -rebuild

The default is to only rebuild java files that are older than the mdo file. If you want to rebuild all then pass -rebuild.

Example OrgPerson.mdo will create OrgPerson.java in the same directory of the .mdo. Note the package name, in this case the .mdo is in the directory: com/hapticapps/amici/shared/data_models/org

package com.hapticapps.amici.shared.data_models.org;

import com.hapticapps.amici.shared.utils.Utils;
import org.bson.codecs.pojo.annotations.BsonProperty;

/**
    The org person
**/
entity OrgPerson {

    index (uuid asc) unique;
    index (name asc) unique;
    index (email asc) unique sparse;
    index (friendIds asc) sparse;

    data String uuid as u = ~Utils.newUID()~;

    data String orgId as o;

    data String name as n;

    data String email as e;

    data Status status as st = ~Status.PENDING~;

    data ~List<String>~ friendIds as f = ~new ArrayList<>()~;

    data ~List<Address>~ addresses as a = ~new ArrayList<>()~;
    
    ...

The output is: output java

    Usage of the output class:
    
    var org = OrgPerson.builder().withOrgId("45").withName("test").build();
    
    // Update the org.  Note the original is not modified.
    var orgUpdate = org.copy().withName("newName").build();

    

Examples

See the samples folder.

• org.mdo
• generated java class

Mongo

This project only contains support for data objects that can be persisted in mongo.

The generated class should fit in your current mongo project, ex:

    
    collection.insertOne( org );
    
    collection.findOne(eq(OrgPerson.BSON_NAME, "test"));
    

These are to be treated as POJO for the mongo services, so the codec registry should be configured:

    ConnectionString connectionString = new ConnectionString(config.url);

    CodecRegistry pojoCodecRegistry = fromProviders(PojoCodecProvider.builder().automatic(true).build());
    CodecRegistry codecRegistry = fromRegistries(MongoClientSettings.getDefaultCodecRegistry(),
            pojoCodecRegistry);


    MongoClientSettings clientSettings = MongoClientSettings.builder()
            .applyConnectionString(connectionString)
            .codecRegistry(codecRegistry)
            .build();

The mdo grammar.

    package package.name;
    
    /**
        Comments
    **/
    import ... ;
    
    entity ClassName {
        
           index ( fieldName asc/desc [, fieldName asc/desc ] ) unique sparse background;
           .. index ..
           
           /**
           Data represents a field.
           Type is the java type (can be a class type)
           ~string~ are identifiers but can have special characters.  For example an
           array.  
           
           data type field [as bsonName] [= initialValue];
           
           */
           data ~Type~ uuid as u = ~new Id()~;
           data ~List<Product>~ products as p = ~new ArrayList<>()~;
    
    } 
    
    enum ClassName {
        Val, Val ...
    }
    
    class ClassName {
        /**
            data fields like the entity.
        */
    }
    
    [enums, classes]

Why setters?

Mongo needs setters and getters for reading and writing the data. At this time I have not found a way around this.
If you want immutable, just use the builder and copy methods to update the data.

Contributing

All contributions are welcome – if you find a bug please report it.

Contributors

• Sam Lotti (slotti@hapticappsllc.com)