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(IContext context)

• context: IContext - (optional) a context to trace execution through a call chain.

ClearSchema

Clears all auto-created objects.

protected void ClearSchema()

CloseAsync

Closes the component and frees used resources.

public virtual Task CloseAsync(IContext context)

• context: IContext - (optional) a context to trace execution through a call chain.

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(IContext context, T item)

• context: IContext - (optional) a context to trace execution through a 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(IContext context)

• context: IContext - (optional) a context to trace execution through a 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(IContext context, string filter)

• context: IContext - (optional) a context to trace execution through a 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(IContext context, string filter)

• context: IContext - (optional) a context to trace execution through a 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(IContext context, string filter, string sort = null, string select = null)

• context: IContext - (optional) a context to trace execution through a 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(IContext context, string filter)

• context: IContext - (optional) a context to trace execution through a 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(IContext context, string filter, PagingParams paging = null, string sort = null, string select = null)

• context: IContext - (optional) a context to trace execution through a 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(IContext context)

• context: IContext - (optional) a context to trace execution through a 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(IContext context, 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" }