collections

While SQL databases use tables, MongoDB uses collections. When an app needs to store a collection of objects (like a list of contacts or a collection of phone numbers) it defines a collections object. Bolt will automatically create the necessary collections for the app, prefixing the name of each collection with the name of the app. So, a collection called students owned by an app call ctl-sms-students with have the full name ctl-sms-students/students.

Say you are working on a Students Managment System, and you need to store a collection of students, your collections could look like this:

"collections": {
    "students": "*"
}

The value on the left (in this case students) is the name of the collection while the value on the right represents what other apps are allowed to read from the collection. The "*" means every app is allowed to read from the collection. You can specify an array of apps that are allowed to read from the collection, as shown below:

"collections": {
    "students": ["bolt-settings", "ctl-sms-home"]
}

From the above snippet, only the apps named bolt-settings and ctl-sms-home are allowed to read from the collection. (Of course, the app that owns a collection is allowed to read from the collection.)

The above snippet can also be rewritten as shown below:

"collections": {
    "students": {
        "guests": ["bolt-settings", "ctl-sms-home"]
    }
}

Using the above syntax, you can give every app read access to the collection as shown below:

"collections": {
    "students": {
        "guests": "*"
    }
}

By default only the app that created a collection has the right to write to that collection. To give other apps write privilege, provide a tenants field for the collection object, as shown below:

"collections": {
    "student-guardian-associations": {
        "tenants": "*"
    },
    "student-scores-associations": {
        "tenants": ["scores-app", "classes-app"]
    }
}

From the snippet above, the collectionstudent-guardian-associations can be written to by every app, while the collection student-scores-associations can be written to by the apps named scores-app and classes-app (in addition to the app that owns the collection). Tenants of a collection, just like the app that owns the collection, have both read and write access to the collection.

You can specify an options field for your collections. This is the same options MongoDB uses when creating a collection. In the options object you can cap a collection or specify validation rules.

For instance, to specify that every document in the students collection must have the following fields:

• a name,
• an id,
• a dateOfBirth,
• and either a phone or an email

"collections": {
    "students": {
        "guests": ["bolt-settings", "ctl-sms-home"],
        "options": {
            "validator": {
                "$and": [
                    { "name": { "$type": "string" } },
                    { "id": { "$type": "number" } },
                    { "dateOfBirth": { "$type": "date" } },
                    {"$or": [
                        { "phone": { "$type": "string" } },
                        { "email": { "$regex": /@gmail\.com$/ } }
                    ]}
                ]
            }
        }
    }
}

To get a list of data types to use in your validator, see here.

To read more on validation see this article and its sequel.

You can also create a capped collection.

"collections": {
    "student-scores-associations": {
        "tenants": ["scores-app", "classes-app"],
        "options": {
            "capped": true,
            "size": 5242880,
            "max": 5000
        }
    }
}

For how to store data to (write) and retrieve data from (read) collections, see bolt-module-db.