Class MigrationContext

Namespace

Typhon.Engine

Assembly

Typhon.Engine.dll

What a migration function (ContextMigrationFunc<TOld, TNew>) can do beyond copying bytes: read the texts of the old value and set the texts of the new one. A String1024 is a handle the engine owns the text of (#1094), so a plain MigrationFunc<TOld, TNew> can only carry an existing one over; giving a new value a text takes this context.

public sealed class MigrationContext

Inheritance

object

MigrationContext

Inherited Members

object.GetType()

object.ToString()

object.Equals(object)

object.Equals(object, object)

object.ReferenceEquals(object, object)

object.GetHashCode()

Remarks

Copying an old value's String1024 into the new value keeps its text: the handle moves with the row. Copy it into at most one field — two fields naming one text would each free it.

The migration may also run a function only to read another field of the converted value (a realm key, say); there the context writes no text: SetText(ref String1024, ReadOnlySpan<char>) leaves the field empty and ReadText(in String1024) reads nothing.

Methods

ReadText(in String1024)

The text field of the OLD value names; empty for no text.

public string ReadText(in String1024 field)

Parameters

field String1024

Returns

string

SetText(ref String1024, ReadOnlySpan<byte>)

The UTF-8 overload of SetText(ref String1024, ReadOnlySpan<char>).

public void SetText(ref String1024 field, ReadOnlySpan<byte> utf8)

Parameters

field String1024

utf8 ReadOnlySpan<byte>

SetText(ref String1024, ReadOnlySpan<char>)

Gives field of the NEW value the text text, cut at MaxUtf8Bytes UTF-8 bytes.

public void SetText(ref String1024 field, ReadOnlySpan<char> text)

Parameters

field String1024

text ReadOnlySpan<char>