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.
Inherited Members
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 |