Show / Hide Table of Contents

Class NpgsqlTypeHandler

Base class for all type handlers, which read and write CLR types into their PostgreSQL binary representation. Type handler writers shouldn't inherit from this class, inherit NpgsqlTypeHandler or NpgsqlSimpleTypeHandler<TDefault> instead.

Inheritance
System.Object
NpgsqlTypeHandler
ArrayHandler
RangeHandler
NpgsqlTypeHandler<TDefault>
Inherited Members
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.TypeHandling
Assembly: Npgsql.dll
Syntax
public abstract class NpgsqlTypeHandler

Constructors

NpgsqlTypeHandler(PostgresType)

Constructs a NpgsqlTypeHandler.

Declaration
protected NpgsqlTypeHandler(PostgresType postgresType)
Parameters
Type Name Description
PostgresType postgresType

Methods

CreateArrayHandler(PostgresArrayType)

Creates a type handler for arrays of this handler's type.

Declaration
public abstract ArrayHandler CreateArrayHandler(PostgresArrayType arrayBackendType)
Parameters
Type Name Description
PostgresArrayType arrayBackendType
Returns
Type Description
ArrayHandler

CreateConversionButNoParamException(Type)

Used to create an exception when the provided type can be converted and written, but an instance of NpgsqlParameter is required for caching of the converted value (in ConvertedValue.

Declaration
protected Exception CreateConversionButNoParamException(Type clrType)
Parameters
Type Name Description
System.Type clrType
Returns
Type Description
System.Exception

CreateRangeHandler(PostgresRangeType)

Creates a type handler for ranges of this handler's type.

Declaration
public abstract RangeHandler CreateRangeHandler(PostgresRangeType rangeBackendType)
Parameters
Type Name Description
PostgresRangeType rangeBackendType
Returns
Type Description
RangeHandler

Read<TAny>(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 abstract TAny Read<TAny>(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
TAny

The fully-read value.

Type Parameters
Name Description
TAny

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 abstract 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

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

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

Declaration
protected abstract 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

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 abstract 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.

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

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

Declaration
protected abstract 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
In This Article
Back to top Generated by DocFX