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MorphiaUser Guide

Overview

Morphia is a Fantom to MongoDB object mapping library.

Morphia is an extension to the Mongo library that maps Fantom objects and their fields to and from MongoDB collections and documents.

Morphia features include:

  • All Fantom literals and BSON types supported by default,
  • Support for embedded / nested Fantom objects,
  • Extensible mapping - add your own custom Converters,
  • Query Builder API.

Note: Morphia has no association with Morphia - the Java to MongoDB mapping library. Well, except for the name of course!

Install

Install Morphia with the Fantom Repository Manager ( fanr ):

C:\> fanr install -r http://repo.status302.com/fanr/ afMorphia

To use in a Fantom project, add a dependency to build.fan:

depends = ["sys 1.0", ..., "afMorphia 1.0"]

Documentation

Full API & fandocs are available on the Status302 repository.

Quick Start

1). Start up an instance of MongoDB:

C:\> mongod

MongoDB starting
db version v2.6.0
waiting for connections on port 27017

2). Create a text file called Example.fan:

using afMorphia
using afBson
using afIoc
using afIocConfig

@Entity
class User {
    @Property ObjectId _id
    @Property Str      name
    @Property Int      age

    new make(|This|in) { in(this) }
}

class Example {
    @Inject { type=User# }
    Datastore? datastore

    Void main() {
        reg := RegistryBuilder().addModulesFromPod(Pod.find("afMorphia")).addModule(ExampleModule#).build.startup
        reg.injectIntoFields(this)

        micky := User {
            it._id  = ObjectId()
            it.name = "Micky Mouse"
            it.age  = 42
        }

        // ---- Create ------
        datastore.insert(micky)

        // ---- Read --------
        q     := Query().field("age").eq(42)
        mouse := (User) datastore.query(q).findOne
        echo(mouse.name)  // --> Micky Mouse

        // ---- Update -----
        mouse.name = "Minny"
        datastore.update(mouse)

        // ---- Delete ------
        datastore.delete(micky)

        reg.shutdown
    }
}

class ExampleModule {
    @Contribute { serviceType=ApplicationDefaults# }
    static Void contributeAppDefaults(Configuration config) {
        config[MorphiaConfigIds.mongoUrl] = `mongodb://localhost:27017/exampledb`
    }
}

3). Run Example.fan as a Fantom script from the command line:

[afIoc] Adding module definitions from pod 'afMorphia'
[afIoc] Adding module definition for afMorphia::MorphiaModule
[afIoc] Adding module definition for afIocConfig::IocConfigModule
[afIoc] Adding module definition for afMorphia::ExampleModule
[afMongo]

     Alien-Factory
 _____ ___ ___ ___ ___
|     | . |   | . | . |
|_|_|_|___|_|_|_  |___|
              |___|1.0.0

Connected to MongoDB v2.6.5 (at mongodb://localhost:27017)

[afIoc]
   ___    __                 _____        _
  / _ |  / /_____  _____    / ___/__  ___/ /_________  __ __
 / _  | / // / -_|/ _  /===/ __// _ \/ _/ __/ _  / __|/ // /
/_/ |_|/_//_/\__|/_//_/   /_/   \_,_/__/\__/____/_/   \_, /
                            Alien-Factory IoC v2.0.2 /___/

IoC Registry built in 355ms and started up in 225ms

Micky Mouse
[afIoc] IoC shutdown in 12ms
[afIoc] "Goodbye!" from afIoc!

Usage

MongoDB Connections

A Mongo Connection URL should be contributed as an application default. This supplies the default database to connect to, along with any default user credentials. Example, in your AppModule:

@Contribute { serviceType=ApplicationDefaults# }
static Void contributeAppDefaults(Configuration config) {
    config[MorphiaConfigIds.mongoUrl] = `mongodb://username:password@localhost:27017/exampledb`
}

Morphia uses the connection URL to create a pooled ConnectionManager. The ConnectionManager, and all of its connections, are gracefully closed when IoC / BedSheet is shutdown.

Some connection URL options are supported:

  • mongodb://username:password@example1.com/database?maxPoolSize=50
  • mongodb://example2.com?minPoolSize=10&maxPoolSize=25

See ConnectionManagerPooled for more details.

Entities

An entity is a top level domain object that is persisted in a MongoDB collection.

Entity objects must be annotated with the @Entity facet. By default the MongoDB collection name is the same as the (unqualified) entity type name. Example, if your entity type is acmeExample::User then it maps to a Mongo collection named User. This may be overriden by providing a value for the @Entity.name attribute.

Entity fields are mapped to properties in a MongoDB document. Use the @Property facet to mark fields that should be mapped to / from a Mongo property. Again, the default is to take the property name and type from the field, but it may be overridden by facet values.

As all MongoDB documents define a unique property named _id, all entities must also define a unique property named _id. Example:

@Entity
class MyEntity {
    @Property
    ObjectId _id
    ...
}

or

@Entity { name="AnotherEntity" }
class MyEntity {
    @Property { name="_id" }
    ObjectId wotever
    ...
}

Note that a Mongo Id does not need to be an ObjectId. Any object may be used, it just needs to be unique.

Datastore

A Datastore wraps a Mongo Collection and is your gateway to saving and reading Fantom objects to / from the MongoDB.

Each Datastore instance is specific to an Entity type, so to inject a Datastore you need to specify which Entity it is associated with. Use the @Inject.type attribute to do this. Example:

@Inject { type=User# }
Datastore userDatastore

You can also inject Mongo Collections in the same manner:

@Inject { type=User# }
Collection userCollection

Mapping

At the core of Morphia is a suite of Converters that map Fantom objects to Mongo documents.

Standard Converters

By default, Morphia provides support and converters for the following Fantom types:

afBson::Binary
   sys::Bool
   sys::Buf
afBson::Code
   sys::Date
   sys::DateTime
   sys::Decimal
   sys::Duration
   sys::Enum
   sys::Float
   sys::Int
   sys::List
   sys::Map
afBson::MaxKey
afBson::MinKey
        null
afBson::ObjectId
   sys::Regex
   sys::Range
   sys::Slot
   sys::Str
afBson::Timestamp
   sys::Type
   sys::Uri

Embedded Objects

Morphia is also able to convert embedded, or nested, Fantom objects. Extending the example in Quick Start, here we substitute the Str name for an embedded Name object:

@Entity
class User {
    @Property ObjectId _id
    @Property Name     name
    @Property Int      age
    new make(|This|in) { in(this) }
}

class Name {
    @Property Str  firstName
    @Property Str  lastName
    new make(|This|in) { in(this) }
}

...

micky := User {
    _id  = ObjectId()
    age  = 42
    name = name {
      firstName = "Micky"
      lastName  = "Mouse"
    }
}
mongoDoc := datastore.toMongoDoc(micky)

echo(mongoDoc) // --> [_id:xxxx, age:42, name:[lastName:Mouse, firstName:Micky]]

Note that embedded Fantom types should not be annotated with @Entity.

Custom Converters

If you want more control over how objects are mapped to and from Mongo, then contribute a custom converter. Do this by implementing Converter and contributing an instance to the Converters service.

Example, to store the Name object as a simple hyphenated string:

const class NameConverter : Converter {

    override Obj? toFantom(Type fantomType, Obj? mongoObj) {
        // decide how you want to handle null values
        if (mongoObj == null) return null

        mong := ((Str) mongoObj).split('-')
        return Name { it.firstName = mong[0]; it.lastName = mong[1] }
    }

    override Obj? toMongo(Obj fantomObj) {
        name := (Name) fantomObj
        return "${name.firstName}-${name.lastName}"
    }
}

Then contribute it in your AppModule:

@Contribute { serviceType=Converters# }
static Void contributeConverters(Configuration config) {
    config[Name#] = NameConverter()
}

To see it in action:

micky := User {
    it._id  = ObjectId()
    it.age  = 42
    it.name = Name {
      it.firstName = "Micky"
      it.lastName  = "Mouse"
    }
}
mongoDoc := datastore.toMongoDoc(micky)

echo(mongoDoc) // --> [_id:xxxx, age:42, name:Micky-Mouse]

Storing Nulls in Mongo

When converting Fantom objects to Mongo, the ObjConverter decides what to do if a Fantom field has the value null. Should it store a key in the MongoDb with a null value, or should it not store the key at all?

To conserve storage space in MongoDB, by default ObjConverter does not store the keys.

If you want to store null values, then create a new ObjConverter passing true into the ctor, and contribute it in your AppModule: Example:

@Contribute { serviceType=Converters# }
static Void contributeConverters(Configuration config) {
    config.overrideValue(Obj#, config.createProxy(Converter#, ObjConverter#,  [true]), "MyObjConverter")
}

(A proxy is required due to the circular nature of Converters.)

See Storing null vs not storing the key at all in MongoDB for more details.

Query API

Querying a MongoDB for documents requires knowledge of their Query Operators. While simple for simple queries:

query := ["age": 42]

It can quickly grow unmanagable and confusing for larger queries. For example, this tangled mess is from the official documentation for the $and operator:

query := [
    "\$and" : [
        ["\$or": [["price": 0.99f], ["price": 1.99f]]],
        ["\$or": [["sale" : true ], ["qty"  : ["\$lt": 20]]]]
    ]
]

For that reason Morphia provides a means to build and execute Query objects that rely on more meaningful method names. The simple example may be re-written as:

query := Query().field("age").eq(42)

Use a QueryExecutor as returned from the Datastore.query(...) method to run the query.

datastore.query(query).findAll

Because you often create Query objects to match fields, it can be helpful to squirrel away this little bit of code in its own method:

QueryCriterion field(Str fieldName) {
    Query().field(fieldName)
}

The more complicated $and example then becomes:

query := Query().and([
    Query().or([ field("price").eq(0.99f), field("price").eq(1.99f)  ]),
    Query().or([ field("sale ").eq(true),  field("qty").lessThan(20) ])
])

Which, even though slightly more verbose, should be much easier to construct, understand, and debug. And the autocomplete nature of IDEs such as F4 means you don't have to constantly consult the Mongo documentation.

Remarks

If you're looking for cross-platform MongoDB GUI client then look no further than Robomongo!

Release Notes

v1.0.2

  • Bug: Binary objects with a generic subtype could not be read from the database as BSON converted them to Buf objects.

v1.0.0

  • New: Introduced the Query Builder API.
  • New: IntSequences services provides an alternative to unique ObjectIDs.
  • New: Mongo Collections maybe injected in the same manner as Datastore objects, using the @Inject.type attribute.

v0.0.10

v0.0.8

v0.0.6

v0.0.4

  • Chg: @Entity facet is now inherited.
  • Bug: Datastore.findOne() and Datastore.get() could throw a NullErr if checked was false.

v0.0.2

  • New: Preview Release