From bfbcc201b72a0a406ff8dffadd6d8dd4bf717015 Mon Sep 17 00:00:00 2001
From: Simon Willison <swillison@gmail.com>
Date: Sat, 15 Mar 2025 19:17:24 -0700
Subject: [PATCH] Don't require input if template does not use $input, closes
 #835

---
 llm/cli.py              |  6 ++++--
 llm/templates.py        |  8 ++++++++
 tests/test_templates.py | 14 ++++++++++++--
 3 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/llm/cli.py b/llm/cli.py
index 20bbdee..fb04dcd 100644
--- a/llm/cli.py
+++ b/llm/cli.py
@@ -397,9 +397,11 @@ def prompt(
         extract_last = template_obj.extract_last
         if template_obj.schema_object:
             schema = template_obj.schema_object
-        prompt = read_prompt()
+        input_ = ""
+        if "input" in template_obj.vars():
+            input_ = read_prompt()
         try:
-            prompt, system = template_obj.evaluate(prompt, params)
+            prompt, system = template_obj.evaluate(input_, params)
         except Template.MissingVariables as ex:
             raise click.ClickException(str(ex))
         if model_id is None and template_obj.model:
diff --git a/llm/templates.py b/llm/templates.py
index 502007f..94a62c3 100644
--- a/llm/templates.py
+++ b/llm/templates.py
@@ -38,6 +38,14 @@ class Template(BaseModel):
             system = self.interpolate(self.system, params)
         return prompt, system
 
+    def vars(self) -> set:
+        all_vars = set()
+        for text in [self.prompt, self.system]:
+            if not text:
+                continue
+            all_vars.update(self.extract_vars(string.Template(text)))
+        return all_vars
+
     @classmethod
     def interpolate(cls, text: Optional[str], params: Dict[str, Any]) -> Optional[str]:
         if not text:
diff --git a/tests/test_templates.py b/tests/test_templates.py
index ba3fe4a..957bd77 100644
--- a/tests/test_templates.py
+++ b/tests/test_templates.py
@@ -146,10 +146,11 @@ def test_templates_error_on_missing_schema(templates_path):
 
 @mock.patch.dict(os.environ, {"OPENAI_API_KEY": "X"})
 @pytest.mark.parametrize(
-    "template,extra_args,expected_model,expected_input,expected_error",
+    "template,input_text,extra_args,expected_model,expected_input,expected_error",
     (
         (
             "'Summarize this: $input'",
+            "Input text",
             [],
             "gpt-4o-mini",
             "Summarize this: Input text",
@@ -157,6 +158,7 @@ def test_templates_error_on_missing_schema(templates_path):
         ),
         (
             "prompt: 'Summarize this: $input'\nmodel: gpt-4",
+            "Input text",
             [],
             "gpt-4",
             "Summarize this: Input text",
@@ -164,6 +166,7 @@ def test_templates_error_on_missing_schema(templates_path):
         ),
         (
             "prompt: 'Summarize this: $input'",
+            "Input text",
             ["-m", "4"],
             "gpt-4",
             "Summarize this: Input text",
@@ -171,6 +174,7 @@ def test_templates_error_on_missing_schema(templates_path):
         ),
         pytest.param(
             "boo",
+            "Input text",
             ["-s", "s"],
             None,
             None,
@@ -179,6 +183,7 @@ def test_templates_error_on_missing_schema(templates_path):
         ),
         pytest.param(
             "prompt: 'Say $hello'",
+            "Input text",
             [],
             None,
             None,
@@ -187,6 +192,7 @@ def test_templates_error_on_missing_schema(templates_path):
         ),
         (
             "prompt: 'Say $hello'",
+            "Input text",
             ["-p", "hello", "Blah"],
             "gpt-4o-mini",
             "Say Blah",
@@ -194,6 +200,7 @@ def test_templates_error_on_missing_schema(templates_path):
         ),
         (
             "prompt: 'Say pelican'",
+            "",
             [],
             "gpt-4o-mini",
             "Say pelican",
@@ -205,6 +212,7 @@ def test_template_basic(
     templates_path,
     mocked_openai_chat,
     template,
+    input_text,
     extra_args,
     expected_model,
     expected_input,
@@ -214,7 +222,9 @@ def test_template_basic(
     runner = CliRunner()
     result = runner.invoke(
         cli,
-        ["--no-stream", "-t", "template", "Input text"] + extra_args,
+        ["--no-stream", "-t", "template"]
+        + ([input_text] if input_text else [])
+        + extra_args,
         catch_exceptions=False,
     )
     if expected_error is None: