MongoDB module

A set of components used to implement MongoDB persistence.

Packages

The module contains the following packages:

Build - factory to create MongoDB persistence components.
Connect - connection component to configure connections to MongoDB databases.
Persistence - abstract persistence components to perform basic CRUD operations.

Use

Install the dotnet package as

dotnet add package PipServices4.Mongodb

As an example, lets create persistence for the following data object.

using PipServices4.Commons.Data;

class MyObject : IIdentifiable<string>
{
    public string Id { get; set; }
    public string key;
    public int value;
}

The persistence component shall implement the following interface with a basic set of CRUD operations:

interface IMyPersistance
{
    void GetPageByFilter(string correlationId, FilterParams filter, PagingParams paging);

    void GetOneById(string correlationId, string id);

    void GetOneByKey(string correlationId, string id);

    void Create(string correlationId, MyObject item);

    void Update(string correlationId, MyObject item);

    void DeleteById(string correlationId, string id);
}

To implement mongodb persistence component you shall inherit IdentifiableMongoDbPersistence. Most CRUD operations will come from the base class. You only need to override GetPageByFilter method with a custom filter function. And then, implement a GetOneByKey custom persistence method that doesn’t exist in the base class.

class MyMongoDbPersistence : IdentifiableMongoDbPersistence<MyObject, string>
{
    public MyMongoDbPersistence() : base("myobjects") { }

    protected override FilterDefinition<MyObject> ComposeFilter(FilterParams filter)
    {
        filter = filter != null ? filter : new FilterParams();

        var criteria = new BsonArray();

        string id = filter.GetAsNullableString("id");
        if (id != null)
            criteria.Add(new BsonDocument("_id", id));

        string tempIds = filter.GetAsNullableString("ids");
        if (tempIds != null)
        {
            string[] ids = tempIds.Split(",");
            criteria.Add(new BsonDocument(new Dictionary<string, object> { { "$in", ids } }));
        }

        string key = filter.GetAsNullableString("key");
        if (key != null)
            criteria.Add(new BsonDocument("key", key));


        return criteria.Count > 0 ? new BsonDocument("$and", criteria) : null;
    }

    public async Task<DataPage<MyObject>> GetPageByFilter(string correlationId, FilterParams filter, PagingParams paging)
    {
        return await base.GetPageByFilterAsync(correlationId, this.ComposeFilter(filter), paging).Result;
    }

    public Task<MyObject> GetOneByKey(string correlationId, string key)
    {
        var filter = new BsonDocument("key", key);
        var item = await this._collection.FindAsync(filter).First<MyObject>();

        if (item == null)
            this._logger.Trace(correlationId, "Nothing found from %s with key = %s", this._collectionName, key);
        else
            this._logger.Trace(correlationId, "Retrieved from %s with key = %s", this._collectionName, key);

        item = this.ConvertToPublic(item);

        return item;
    }
}

The configuration for your microservice that includes mongodb persistence may look the following way:

...
{{#if MONGODB_ENABLED}}
- descriptor: pip-services:connection:mongodb:con1:1.0
  collection: {{MONGO_COLLECTION}}{{#unless MONGO_COLLECTION}}myobjects{{/unless}}
  connection:
    uri: {{{MONGO_SERVICE_URI}}}
    host: {{{MONGO_SERVICE_HOST}}}{{#unless MONGO_SERVICE_HOST}}localhost{{/unless}}
    port: {{MONGO_SERVICE_PORT}}{{#unless MONGO_SERVICE_PORT}}27017{{/unless}}
    database: {{MONGO_DB}}{{#unless MONGO_DB}}app{{/unless}}
  credential:
    username: {{MONGO_USER}}
    password: {{MONGO_PASS}}
    
- descriptor: myservice:persistence:mongodb:default:1.0
  dependencies:
    connection: pip-services:connection:mongodb:con1:1.0
{{/if}}
...