feat: Add config based template to query function (#177)

embedchain/config/QueryConfig.py

@@ -1,8 +1,36 @@
 from embedchain.config.BaseConfig import BaseConfig
+from string import Template
+import re
+
+
+DEFAULT_PROMPT_TEMPLATE = Template("""
+  Use the following pieces of context to answer the query at the end.
+  If you don't know the answer, just say that you don't know, don't try to make up an answer.
+
+  $context
+  
+  Query: $query
+  
+  Helpful Answer:
+""")
+query_re = re.compile(r"\$\{*query\}*")
+context_re = re.compile(r"\$\{*context\}*")
+
 
 class QueryConfig(BaseConfig):
     """
     Config for the `query` method.
     """
-    def __init__(self):
-        pass
+    def __init__(self, template: Template = None):
+        """
+        Initializes the QueryConfig instance.
+
+        :param template: Optional. The `Template` instance to use as a template for prompt.
+        :raises ValueError: If the template is not valid as template should contain $context and $query
+        """
+        if template is None:
+            template = DEFAULT_PROMPT_TEMPLATE
+        if not (re.search(query_re, template.template) \
+            and re.search(context_re, template.template)):
+            raise ValueError("`template` should have `query` and `context` keys")
+        self.template = template