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Interface INpgsqlTypeHandler<T>

Type handlers that wish to support reading other types in additional to the main one can implement this interface for all those types.

Namespace: Npgsql.TypeHandling
Assembly: Npgsql.dll
Syntax
public interface INpgsqlTypeHandler<T>
Type Parameters
Name Description
T

Methods

Read(NpgsqlReadBuffer, Int32, Boolean, FieldDescription)

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

Declaration
ValueTask<T> Read(NpgsqlReadBuffer buf, int len, bool async, FieldDescription fieldDescription)
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
System.Threading.Tasks.ValueTask<T>

The fully-read value.

ValidateAndGetLength(T, 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
int ValidateAndGetLength(T value, ref NpgsqlLengthCache lengthCache, NpgsqlParameter parameter)
Parameters
Type Name Description
T value

The value to be written to PostgreSQL

NpgsqlLengthCache lengthCache

A cache where the length calculated during the validation phase can be stored for use at the writing phase.

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.

Write(T, NpgsqlWriteBuffer, NpgsqlLengthCache, NpgsqlParameter, Boolean)

Writes a value to the provided buffer.

Declaration
Task Write(T value, NpgsqlWriteBuffer buf, NpgsqlLengthCache lengthCache, NpgsqlParameter parameter, bool async)
Parameters
Type Name Description
T value

The value to write.

NpgsqlWriteBuffer buf

The buffer to which to write.

NpgsqlLengthCache lengthCache

A cache where the length calculated during the validation phase can be stored for use at the writing phase.

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 will be necessary (i.e. the buffer is full), determines whether it will be done synchronously or asynchronously.

Returns
Type Description
System.Threading.Tasks.Task
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