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    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
    Object
    NpgsqlTypeHandler
    ArrayHandler
    RangeHandler
    NpgsqlTypeHandler<TDefault>
    Inherited Members
    Object.Equals(Object)
    Object.Equals(Object, Object)
    Object.GetHashCode()
    Object.GetType()
    Object.MemberwiseClone()
    Object.ReferenceEquals(Object, Object)
    Object.ToString()
    Namespace: Npgsql.TypeHandling
    Assembly: Npgsql.dll
    Syntax
    public abstract class NpgsqlTypeHandler

    Constructors

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    NpgsqlTypeHandler(PostgresType)

    Constructs a NpgsqlTypeHandler.

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

    Methods

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    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
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    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
    Type clrType
    Returns
    Type Description
    Exception
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    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
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    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.

    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
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    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.

    Int32 len

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

    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
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    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
    Int32
    Type Parameters
    Name Description
    TAny
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    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
    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
    Int32

    The number of bytes required to write the value.

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    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
    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).

    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
    Task
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