Mongirl💾- The Java-Object storing for MongoDB

Mongirl stores Java objects annotation-based to MongoDBs, so you never need to write codecs again.

Take a look at this example:

@Store(collection = "myMongoCollection")
class Example {
   @StoreWith(key = "privId")
   private int id = 42;
 
   @StoreWith
   public String username = "Panda";
 
   @StoreWith
   private SubExample subEx = new SubExample();
}

@Store(collection = "subobjects")
class SubExample {
   @StoreWith
   private String foo = "bar";
}

... will result in the database entries:

• Collection "myMongoCollection"

{
 _id: ObjectId('...')
 privId: 42
 username: "Panda"
 subEx: ObjectId('ABC')
}

• Collection "subobjects"

{
 _id: ObjectId('ABC')
 foo: "bar"
}

Initialization / Connect Mongirl

Initialize Mongirl (with credentials)

To connect Mongirl to a MongoDB secured by credentials, use: new Mongirl(host, port, dbName, username, authDB, password) while the parameters are:

• host: String | Host IP adress of the MongoDB. localhost is a valid value
• port: int | The Port of the MongoDB. Default value for MongoDBs is 27017
• dbName: String | The name of the database in the MongoDB
• username: String | The username of the MongoDB login
• authDB: String | The database auth. May be equal to the database name
• password: String | The password according to the username and auth

Initialize Mongirl without credentials

Use the simplified constructor: new Mongirl(host, port, dbName) while the parameters are:

• host: String | Host IP adress of the MongoDB. localhost is a valid value
• port: int | The Port of the MongoDB. Default value for MongoDBs are 27017
• dbName: String | The name of the database in the MongoDB

Annotations for classes

@Store

Enables storage operations based on the attributes annotations and the following specification:

Parameter	Optional	Description
collection	required	The name of the MongoDB collection where objects of this type should be stored
addClasspath	true (default false)	When true, Mongirl will insert a field named classPath to the MongoDB object of the encoded Java Object to determine the right class in the decode process. Only important for subclasses and interface implementations. Since v1.12, Mongirl adds the classpath for subclasses and interface implementations by itself.

@Dataclass

Stores all attributes of the class, no further @StoreWith annotations needed. If a field annotated with @StoreWith and non-default parameters, the non-default parameters will be used for the store process. Fields in Dataclasses annotated with @DontStore won't be stored.

Parameter	Optional	Description
collection	required	The name of the MongoDB collection where objects of this class should be stored
addClasspath	optional (default false)	With true, Mongirl will insert a field named classPath to the MongoDB object of the encoded Java Object to determine the right class in the decode process. Only important for subclasses and interface implementations. Since v1.12, Mongirl adds the classpath for subclasses and interface implementations by itself
allAttributesEqualRelevant	optional (default true)	To identify the objects database entry, Mongirl looks for equal attribute values from attributes annotated with @Store(equalityRequirement = true, ...). With this option set to true, all attributes are implicitly relevant for the equality check. This will result in two objects with the sane values for all stored attributes won't stored seperately. They will be only stored one object for both as long as they have the same attribute values. By the moment when any attribute value changes and the object is stored via store, Mongirl will create a second object with the changed values for it

Annotations for attributes

@StoreWith

Indicates an attribute to be stored if an object from the attributes class is being stored. The annotation provides the following parameters:

Parameter	Default	Description
key	field name	Specifies the attributes name in the MongoDB objects
equalityRequirement	false	Specifies whether an attributes is part of an unique identification of its object. With set to true, this attribute will used to check, whether an database entry is the same as a given object. In most cases, attributes like id, email, uniqueUsername or uuid should be annotated with equalityRequirement = true. If no attribute is annotated with this parameter set to true, an object of this class will result in a new database entry on every store operation since Mongirl cannot determine whether an stored entry belongs to the given object based on values of equalityRequirement attributes.

API

store

Parameter	Description
object	An object with annotated attributes to store.

After annotating the objects attributes, the store operation will store the object with the annotated attributes as key/values in a MongoDB document to the MongoDB. If an object is already stored in the database (which is determined through the @StoreWith annotation with equalityRequirement = true), the store operation will update the regarding database entry to the current values. Otherwise, if the object wasn't stored before, this operation creates a new MongoDB document in the collection specified in the @Store annotation from the objects class.

Returns the MongoDB-ObjectId in the case when the object was updated or the InsertedId when the object was newly stored.

getObjectIdFrom

Parameter	Description
object	An java object stored in the database.

Returnes the MongoDB-ObjectId from the given java object if it's stored. Otherwise returns null.

decodeFromFilters

Parameter	Description
targetClass	The java class of the object to decode.
...filters	Array containing key/valuePairs with specify the target object.

Decodes a database stored object based on given filters and the class of the to be decoded object.

decodeAll

Parameter	Description
targetClass	The java class of the objects to decode.

Decodes all objects stored in the MongoDB from the collection named in the annotation parameter collection of @Store or @Dataclass. Returns them in a List.

Important notes

Constructors

• Every class from which objects should be stored must have a public constructor. It does not matter whether it's a default constructor or some with parameters. Without, Mongirl cannot instantiate this class objects on decode operations.

Arrays

• Currently, only one-dimensional Arrays are supported

Interfaces implementations

• addClasspath is an optional attribute for @Store for classes implementing an Interface or subclasses. It avoids issues on decoding to these classes.
• By v1.12 - Mongirl will automatically annotate interface implementations and subclasses

Dataclasses

• Dataclasses (annotated by @Dataclass(collection = ...)) have all attributes implicitly annotated as equality requirement fields. So, in the database, there wouldn't be multiple equal entries. Use allAttributesEqualRelevant = false in the @DataClass annotation params to change.