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Class ArrayHandler<TElement>

Base class for all type handlers which handle PostgreSQL arrays.

Inheritance
System.Object
NpgsqlTypeHandler
ArrayHandler
ArrayHandler<TElement>
BitStringArrayHandler
Inherited Members
ArrayHandler.CreateArrayHandler(PostgresArrayType)
ArrayHandler.CreateRangeHandler(PostgresRangeType)
NpgsqlTypeHandler.CreateConversionButNoParamException(Type)
System.Object.ToString()
System.Object.Equals(System.Object)
System.Object.Equals(System.Object, System.Object)
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.GetHashCode()
System.Object.GetType()
System.Object.MemberwiseClone()
Namespace: Npgsql.TypeHandlers
Assembly: Npgsql.dll
Syntax
public class ArrayHandler<TElement> : ArrayHandler
Type Parameters
Name Description
TElement
Remarks

http://www.postgresql.org/docs/current/static/arrays.html.

The type handler API allows customizing Npgsql's behavior in powerful ways. However, although it is public, it should be considered somewhat unstable, and may change in breaking ways, including in non-major releases. Use it at your own risk.

Constructors

ArrayHandler(PostgresType, NpgsqlTypeHandler, Int32)

Declaration
public ArrayHandler(PostgresType arrayPostgresType, NpgsqlTypeHandler elementHandler, int lowerBound = 1)
Parameters
Type Name Description
PostgresType arrayPostgresType
NpgsqlTypeHandler elementHandler
System.Int32 lowerBound

Methods

Read<TRequestedArray>(NpgsqlReadBuffer, Int32, FieldDescription)

Reads a value of type TAny with the given length from the provided buffer, with the assumption that it is entirely present in the provided memory buffer and no I/O will be required. This can save the overhead of async functions and improves performance.

Declaration
public override TRequestedArray Read<TRequestedArray>(NpgsqlReadBuffer buf, int len, FieldDescription fieldDescription = null)
Parameters
Type Name Description
NpgsqlReadBuffer buf

The buffer from which to read.

System.Int32 len

The byte length of the value. The buffer might not contain the full length, requiring I/O to be performed.

FieldDescription fieldDescription

Additional PostgreSQL information about the type, such as the length in varchar(30).

Returns
Type Description
TRequestedArray

The fully-read value.

Type Parameters
Name Description
TRequestedArray
Overrides
NpgsqlTypeHandler.Read<TAny>(NpgsqlReadBuffer, Int32, FieldDescription)

Read<TAny>(NpgsqlReadBuffer, Int32, Boolean, FieldDescription)

Reads a value of type TAny with the given length from the provided buffer, using either sync or async I/O.

Declaration
protected override ValueTask<TAny> Read<TAny>(NpgsqlReadBuffer buf, int len, bool async, FieldDescription fieldDescription = null)
Parameters
Type Name Description
NpgsqlReadBuffer buf

The buffer from which to read.

System.Int32 len

The byte length of the value. The buffer might not contain the full length, requiring I/O to be performed.

System.Boolean async

If I/O is required to read the full length of the value, whether it should be performed synchronously or asynchronously.

FieldDescription fieldDescription

Additional PostgreSQL information about the type, such as the length in varchar(30).

Returns
Type Description
ValueTask<TAny>

The fully-read value.

Type Parameters
Name Description
TAny
Overrides
NpgsqlTypeHandler.Read<TAny>(NpgsqlReadBuffer, Int32, Boolean, FieldDescription)

ReadArray<TAnyElement>(NpgsqlReadBuffer, Boolean, Int32)

Reads an array of element type TAnyElement from the given buffer buf.

Declaration
protected ValueTask<Array> ReadArray<TAnyElement>(NpgsqlReadBuffer buf, bool async, int expectedDimensions = 0)
Parameters
Type Name Description
NpgsqlReadBuffer buf
System.Boolean async
System.Int32 expectedDimensions
Returns
Type Description
ValueTask<System.Array>
Type Parameters
Name Description
TAnyElement

ReadList<TAnyElement>(NpgsqlReadBuffer, Boolean)

Reads an array of element type TAnyElement from the given buffer buf.

Declaration
protected ValueTask<List<TAnyElement>> ReadList<TAnyElement>(NpgsqlReadBuffer buf, bool async)
Parameters
Type Name Description
NpgsqlReadBuffer buf
System.Boolean async
Returns
Type Description
ValueTask<System.Collections.Generic.List<TAnyElement>>
Type Parameters
Name Description
TAnyElement

ValidateAndGetLength<TAny>(TAny, ref NpgsqlLengthCache, NpgsqlParameter)

Called to validate and get the length of a value of a generic NpgsqlParameter<T>.

Declaration
protected override int ValidateAndGetLength<TAny>(TAny value, ref NpgsqlLengthCache lengthCache, NpgsqlParameter parameter)
Parameters
Type Name Description
TAny value
NpgsqlLengthCache lengthCache
NpgsqlParameter parameter
Returns
Type Description
System.Int32
Type Parameters
Name Description
TAny
Overrides
Npgsql.TypeHandling.NpgsqlTypeHandler.ValidateAndGetLength<TAny>(TAny, Npgsql.NpgsqlLengthCache, Npgsql.NpgsqlParameter)

ValidateObjectAndGetLength(Object, ref NpgsqlLengthCache, NpgsqlParameter)

Responsible for validating that a value represents a value of the correct and which can be written for PostgreSQL - if the value cannot be written for any reason, an exception shold be thrown. Also returns the byte length needed to write the value.

Declaration
protected override int ValidateObjectAndGetLength(object value, ref NpgsqlLengthCache lengthCache, NpgsqlParameter parameter)
Parameters
Type Name Description
System.Object value

The value to be written to PostgreSQL

NpgsqlLengthCache lengthCache

If the byte length calculation is costly (e.g. for UTF-8 strings), its result can be stored in the length cache to be reused in the writing process, preventing recalculation.

NpgsqlParameter parameter

The NpgsqlParameter instance where this value resides. Can be used to access additional information relevant to the write process (e.g. Size).

Returns
Type Description
System.Int32

The number of bytes required to write the value.

Overrides
NpgsqlTypeHandler.ValidateObjectAndGetLength(Object, ref NpgsqlLengthCache, NpgsqlParameter)

WriteObjectWithLength(Object, NpgsqlWriteBuffer, NpgsqlLengthCache, NpgsqlParameter, Boolean)

Writes a value to the provided buffer, using either sync or async I/O.

Declaration
protected override Task WriteObjectWithLength(object value, NpgsqlWriteBuffer buf, NpgsqlLengthCache lengthCache, NpgsqlParameter parameter, bool async)
Parameters
Type Name Description
System.Object value

The value to write.

NpgsqlWriteBuffer buf

The buffer to which to write.

NpgsqlLengthCache lengthCache
NpgsqlParameter parameter

The NpgsqlParameter instance where this value resides. Can be used to access additional information relevant to the write process (e.g. Size).

System.Boolean async

If I/O is required to read the full length of the value, whether it should be performed synchronously or asynchronously.

Returns
Type Description
System.Threading.Tasks.Task
Overrides
NpgsqlTypeHandler.WriteObjectWithLength(Object, NpgsqlWriteBuffer, NpgsqlLengthCache, NpgsqlParameter, Boolean)
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