PostgresPersistence

Inherits: IReferenceable, IUnreferenceable, IConfigurable, IOpenable, ICleanable

Description

The PostgresPersistence class allows you to create persistence components that store data in PostgreSQL using the official driver.

Important points

• This is the most basic persistence component that is only able to store data items of any type.
• Specific CRUD operations over the data items must be implemented in child classes by accessing this._db or this._collection properties.

Configuration parameters

• collection: (optional) PostgreSQL collection name connection(s):
• discovery_key: (optional) key to retrieve the connection from IDiscovery
• host: host name or IP address
• port: port number (default: 27017)
• uri: resource URI or connection string with all parameters in it

credential(s):

• store_key: (optional) key to retrieve the credentials from ICredentialStore
• username: (optional) username
• password: (optional) user’s password

options:

• connect_timeout: (optional) number of milliseconds to wait before timing out when connecting a new client (default: 0)
• idle_timeout: (optional) number of milliseconds a client must sit idle in the pool and not be checked out (default: 10000)
• max_pool_size: (optional) maximum number of clients the pool can contain (default: 10)

References

• *:logger:*:*:1.0 - (optional) ILogger components to pass log messages
• *:discovery:*:*:1.0 - (optional) IDiscovery services
• *:credential-store:*:*:1.0 - (optional) credential stores to resolve credentials

Constructors

Creates a new instance of the persistence component.

public PostgresPersistence(string tableName = null, string schemaName = null)

• tableName: string - (optional) table name.
• schemaName: string - (optional) schema name.

Fields

Instance methods

ClearAsync

Clears a component’s state.

public virtual Task ClearAsync(string correlationId)

• correlationId: string- object to convert from the public partial format.

ClearSchema

Clears all auto-created objects.

protected void ClearSchema()

CloseAsync

Closes the component and frees used resources.

public virtual Task CloseAsync(string correlationId)

• correlationId: string- object to convert from the public partial format.

Configure

Configures the component.

public virtual void Configure(ConfigParams config)

• config: ConfigParams - configuration parameters to set.

ConvertFromPublic

Converts an object value from public to internal format.

protected virtual AnyValueMap ConvertFromPublic(T value)

• value: T - object in public format to convert.
• returns: AnyValueMap - converted object in internal format.

ConvertToPublic

Converts an object value from internal to public format.

protected virtual T ConvertToPublic(AnyValueMap map)

• value: AnyValueMap - object in internal format to convert.
• returns: T - converted object in public format.

CreateAsync

Creates a data item.

public virtual Task<T> CreateAsync(string correlationId, T item)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.
• item: T - item to be created.
• returns: Task<T> - created item

CreateSchemaAsync

Checks if a table exists and if it doesn’t, it creates the necessary database objects.

protected Task CreateSchemaAsync(string correlationId)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.

DefineSchema

Defines database schema via auto create objects or convenience methods.

protected virtual void DefineSchema()

deleteByFilter

Deletes data items that match to a given filter. This method shall be called by a public DeleteByFilterAsync method from a child class that receives FilterParams and converts them into a filter function.

public virtual Task DeleteByFilterAsync(string correlationId, string filter)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.
• filter: string - (optional) filter for JSON object.

EnsureIndex

Adds index definition to create it on opening.

protected void EnsureIndex(string name, Dictionary<string, bool> keys, IndexOptions options)

• name: string - the index name.
• keys: Dictionary<string, bool> - index keys (fields).
• options: IndexOptions - index options.

EnsureSchema

Adds a statement to schema definition.

protected void EnsureSchema(string schemaStatement)

• schemaStatement: string - statement to be added to the schema

GenerateColumns

Generates a list of column names to use in SQL statements like: “column1,column2,column3”.

protected string GenerateColumns(AnyValueMap map)

• map: AnyValueMap - array with column values or a key-value map
• returns: string - generated list of column names

GenerateParameters

Generates a list of value parameters to use in SQL statements like: “@Param1,@Param2,@Param3”

protected string GenerateParameters(AnyValueMap map)

• map: AnyValueMap - array with values or a key-value map
• returns: string - generated list of value parameters

Generates a list of column sets to use in UPDATE statements like: column1=%s,column2=%s.

protected string GenerateParameters<K>(IEnumerable<K> values)

• values: IEnumerable<K> - key-value map with columns and values
• returns: string - generated list of column sets

GenerateValues

Generates a list of column parameters.

protected List<object> GenerateValues(AnyValueMap map)

• values: AnyValueMap - key-value map with columns and values
• returns: List<object> - generated list of column values

GetCountByFilterAsync

Gets a number of data items retrieved by a given filter.

This method shall be called by a public GetCountByFilterAsync method from a child class that receives FilterParams and converts them into a filter function.

protected virtual Task<long> GetCountByFilterAsync(string correlationId, string filter)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.
• filter: string - (optional) JSON object filter.
• returns: Task<long> - number of filtered items.

GetListByFilterAsync

Gets a list of data items retrieved by a given filter and sorted according to sort parameters.

This method shall be called by a public GetListByFilterAsync method from a child class that receives FilterParams and converts them into a filter function.

protected Task<List<T>> GetListByFilterAsync(string correlationId, string filter, string sort = null, string select = null)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.
• filter: string - (optional) filter function to filter items
• sort: string - (optional) sorting parameters
• select: string - (optional) projection parameters (not used yet)
• returns: Task<List<T>> - data list of filtered results.

GetOneRandomAsync

Gets a random item from items that match to a given filter.

This method shall be called by a public getOneRandom method from a child class that receives FilterParams and converts them into a filter function.

protected virtual Task<T> GetOneRandomAsync(string correlationId, string filter)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.
• filter: string - (optional) filter for JSON objects
• returns: Task<T> - random item.

GetPageByFilterAsync

Gets a page of data items retrieved by a given filter and sorted according to sort parameters.

This method shall be called by a public GetPageByFilterAsync method from a child class that receives FilterParams and converts them into a filter function.

public virtual Task<DataPage> GetPageByFilterAsync(string correlationId, string filter, PagingParams paging = null, string sort = null, string select = null)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.
• filter: string - (optional) filter for JSON objects
• paging: PagingParams - (optional) paging parameters
• sort: string - (optional) sorting JSON object
• select: string - (optional) projection JSON object
• returns: Task<DataPage> - data page with filtered result

IsOpen

Checks if the component is open.

public virtual bool IsOpen()

• returns: bool - true if the component is open and talse otherwise.

OpenAsync

Opens the component.

public virtual Task OpenAsync(string correlationId)

• correlationId: string - (optional) transaction id used to trace execution through the call chain.

QuoteIdentifier

Adds a single quote to each side of the string.

protected string QuoteIdentifier(string value)

• value: string - string where quotes need to be added
• returns: string - string with added quotes

SetReferences

Sets references to dependent components.

public virtual void SetReferences(IReferences references)

• references: IReferences - references to locate the component’s dependencies.

UnsetReferences

Unsets (clears) previously set references to dependent components.

public virtual void UnsetReferences()

Examples

class MyPostgresPersistence: PostgresPersistence<MyData> 
{
    public MyPostgresPersistence(): base("mydata") { }
    
    public MyData getByName(string correlationId, string name)
    {
        var builder = Builders<BeaconV1>.Filter;
        var filter = builder.Eq(x => x.Name, name);
        var result = await _collection.Find(filter).FirstOrDefaultAsync();
        return result;
    }
    public MyData set(String correlatonId, MyData item)
    {
        var filter = Builders<T>.Filter.Eq(x => x.Id, item.Id);
        var options = new FindOneAndReplaceOptions<T>
        {
            ReturnDocument = ReturnDocument.After,
            IsUpsert = true
        };
        var result = await _collection.FindOneAndReplaceAsync(filter, item, options);
        return result;
    }
}
 
var persistence = new MyPostgresPersistence();
persistence.Configure(ConfigParams.FromTuples(
  "host", "localhost",
  "port", 27017 )
);

persitence.Open("123");
var mydata = new MyData("ABC");
persistence.Set("123", mydata);
persistence.GetByName("123", "ABC");
Console.Out.WriteLine(item);                   // Result: { name: "ABC" }