Context formatting and injection in LangChain - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a prompt template with a variable placeholder.

LangChain

from langchain import PromptTemplate

prompt = PromptTemplate(template="Hello, [1]!", input_variables=["name"])

Drag options to blanks, or click blank then click option'

Aname

Buser

Cinput

Dtext

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name in input_variables that does not match the placeholder.

Forgetting to include the variable in input_variables list.

The input variable name must match the placeholder in the template exactly, so 'name' is correct.

2fill in blank

medium

Complete the code to format the prompt with the variable 'name' set to 'Alice'.

LangChain

formatted_prompt = prompt.format([1]="Alice")

Drag options to blanks, or click blank then click option'

Auser

Bname

Cinput

Dtext

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different variable name than defined in the template.

Passing the variable as a positional argument instead of keyword.

The format method requires the variable name matching the input_variables, which is 'name'.

3fill in blank

hard

Fix the error in the code to inject context into the prompt template.

LangChain

context = "You are a helpful assistant."
prompt = PromptTemplate(template="Context: [1]\nQuestion: {question}", input_variables=["context", "question"])

Drag options to blanks, or click blank then click option'

Atext

Bquestion

Ccontext

Dinput

Attempts:

3 left

💡 Hint

Common Mistakes

Using a placeholder that is not in input_variables.

Mixing curly braces syntax for placeholders.

The placeholder must match an input variable; here 'context' is correct to inject the context string.

4fill in blank

hard

Fill both blanks to create a prompt template that includes context and question variables.

LangChain

prompt = PromptTemplate(template="Context: [1]\nQuestion: [2]", input_variables=["context", "question"])

Drag options to blanks, or click blank then click option'

Acontext

Bquestion

Cinput

Dtext

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the variable names in placeholders.

Using variable names not listed in input_variables.

The placeholders must match the input_variables 'context' and 'question' respectively.

5fill in blank

hard

Fill all three blanks to format the prompt with context and question values.

LangChain

formatted = prompt.format([1]="You are a bot.", [2]="What is AI?", [3]="ignored")

Drag options to blanks, or click blank then click option'

Acontext

Bquestion

Cextra

Dtext

Attempts:

3 left

💡 Hint

Common Mistakes

Using variable names not defined in the prompt template.

Passing positional arguments instead of keyword arguments.

The format method keys must match input_variables; 'context' and 'question' are used, 'extra' is an extra variable.

Practice

1. What is the main purpose of context formatting in Langchain?

easy

A. To create database connections

B. To execute code asynchronously

C. To prepare prompts with placeholders for dynamic data

D. To store user credentials securely

Solution

1. Step 1: Understand context formatting

   Context formatting is about creating prompt templates with placeholders that can be filled later.

2. Step 2: Identify the purpose

   This allows dynamic injection of data into prompts, making AI responses relevant.

3. Final Answer:

   To prepare prompts with placeholders for dynamic data -> Option C

4. Quick Check:

   Context formatting = placeholders in prompts [OK]

Hint: Think of placeholders as empty boxes to fill later [OK]

Common Mistakes:

• Confusing context formatting with code execution
• Thinking it stores credentials
• Mixing it with database operations

2. Which of the following is the correct way to inject a variable user_name into a Langchain prompt template?

easy

A. prompt_template.inject(user_name)

B. prompt_template.append(user_name)

C. prompt_template.fill(user_name)

D. prompt_template.format(user_name=user_name)

Solution

1. Step 1: Recall Langchain prompt syntax

   Langchain uses the format() method to fill placeholders in prompt templates.

2. Step 2: Match method to injection

   Only format(user_name=user_name) correctly injects the variable into the placeholder.

3. Final Answer:

   prompt_template.format(user_name=user_name) -> Option D

4. Quick Check:

   Use format() to inject variables [OK]

Hint: Use .format() to fill placeholders in templates [OK]

Common Mistakes:

• Using non-existent methods like inject() or fill()
• Trying to append variables instead of formatting
• Forgetting to name the variable in format()

3. Given this code snippet:

template = "Hello, {name}! Today is {day}."
prompt = template.format(name="Alice", day="Monday")
print(prompt)

What will be the output?

medium

A. Hello, Alice! Today is Monday.

B. Hello, name! Today is day.

C. Hello, {name}! Today is {day}.

D. Error: Missing placeholders

Solution

1. Step 1: Understand the template string

   The template has placeholders {name} and {day} to be replaced by actual values.

2. Step 2: Apply the format method

   Calling format(name="Alice", day="Monday") replaces placeholders with given values.

3. Final Answer:

   Hello, Alice! Today is Monday. -> Option A

4. Quick Check:

   Placeholders replaced by values = output string [OK]

Hint: format() replaces placeholders with given values [OK]

Common Mistakes:

• Printing the template without formatting
• Confusing placeholder names with literal text
• Expecting an error when placeholders are correctly filled

4. Identify the error in this Langchain prompt injection code:

template = "Welcome, {user}!"
prompt = template.format(user)
print(prompt)

medium

A. Incorrect placeholder syntax in template

B. Missing variable name in format() call

C. Using print() instead of return

D. Template string should use double braces {{}}

Solution

1. Step 1: Check format() usage

   The format method requires named arguments matching placeholders or positional arguments in order.

2. Step 2: Identify missing variable name

   Here, format(user) passes a positional argument but the placeholder expects a named argument {user}.

3. Final Answer:

   Missing variable name in format() call -> Option B

4. Quick Check:

   Named placeholders need named arguments in format() [OK]

Hint: Match placeholder names with named format() arguments [OK]

Common Mistakes:

• Passing positional argument without naming it
• Thinking placeholder syntax is wrong
• Confusing print() with return statements

5. You want to create a prompt that greets a user and mentions their favorite color using Langchain. Which code correctly formats and injects the context for user_name = "Bob" and color = "blue"?

hard

A. template = "Hi {user_name}, your favorite color is {color}."
prompt = template.format(user_name=user_name, color=color)

B. template = "Hi {user}, your favorite color is {color}."
prompt = template.format(user_name=user_name, color=color)

C. template = "Hi {user_name}, your favorite color is {color}."
prompt = template.format(user=user_name, color=color)

D. template = "Hi {user_name}, your favorite color is {color}."
prompt = template.fill(user_name, color)

Solution

1. Step 1: Match placeholders with variable names

   The template uses placeholders {user_name} and {color}, so format() must use these exact names.

2. Step 2: Check format() arguments

   template = "Hi {user_name}, your favorite color is {color}." prompt = template.format(user_name=user_name, color=color) correctly passes named arguments matching placeholders: user_name=user_name, color=color.

3. Step 3: Eliminate incorrect options

   template = "Hi {user}, your favorite color is {color}." prompt = template.format(user_name=user_name, color=color) uses {user} placeholder mismatching the user_name= argument. template = "Hi {user_name}, your favorite color is {color}." prompt = template.format(user=user_name, color=color) mismatches placeholder and argument names. template = "Hi {user_name}, your favorite color is {color}." prompt = template.fill(user_name, color) uses non-existent fill() method.

4. Final Answer:

   template = "Hi {user_name}, your favorite color is {color}." prompt = template.format(user_name=user_name, color=color) -> Option A

5. Quick Check:

   Placeholder names must match format() argument names [OK]

Hint: Keep placeholder and format() argument names identical [OK]

Common Mistakes:

• Mismatching placeholder and argument names
• Using wrong method like fill()
• Ignoring placeholder names in template