MessagePlaceholder constructor
const
MessagePlaceholder({
- required String variableName,
Prompt template that assumes the variable is a ChatMessage (ChatMessageType.messagePlaceholder).
This is useful when you want to use a single ChatMessage in the prompt.
For example, when you decide the type of message at runtime (e.g.
HumanChatMessage or FunctionChatMessage
).
If you need to add multiple messages, use MessagesPlaceholder.
Example:
ChatPromptTemplate.fromPromptMessages([
ChatMessagePromptTemplate.system('You are a helpful AI assistant'),
ChatMessagePromptTemplate.messagesPlaceholder('history'),
ChatMessagePromptTemplate.messagePlaceholder('input'),
]);
Alternatively, you can use ChatPromptTemplate.fromTemplates to achieve the same result.
final promptTemplate = ChatPromptTemplate.fromTemplates([
(ChatMessageType.system, 'You are a helpful AI assistant'),
(ChatMessageType.messagesPlaceholder, 'history'),
(ChatMessageType.messagePlaceholder, 'input'),
]);
Implementation
const MessagePlaceholder({required this.variableName})
: super(prompt: const PromptTemplate(inputVariables: {}, template: ''));