PromptTemplate basics in LangChain - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a PromptTemplate with a template string.

LangChain

from langchain import PromptTemplate

template = "Hello, my name is {name}."
prompt = PromptTemplate(template=[1], input_variables=["name"])

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

A"Hello, my name is name."

BHello, my name is {name}.

C'Hello, my name is name.'

D"Hello, my name is {name}."

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put quotes around the template string.

Using single quotes without curly braces for variables.

The template string must be passed as a string with curly braces for variables, so it needs to be quoted properly.

2fill in blank

medium

Complete the code to specify the input variables for the PromptTemplate.

LangChain

from langchain import PromptTemplate

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

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

A["name"]

B{"name"}

C"name"

Dname

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a string instead of a list.

Using curly braces which create a set, not a list.

input_variables must be a list of strings, so it needs to be in square brackets.

3fill in blank

hard

Fix the error in the code to correctly create a PromptTemplate with two input variables.

LangChain

from langchain import PromptTemplate

template = "My name is {name} and I am {age} years old."
prompt = PromptTemplate(template=template, input_variables=[1])

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

A["name", "age"]

B[name, age]

C{"name", "age"}

D[name, "age"]

Attempts:

3 left

💡 Hint

Common Mistakes

Not quoting variable names inside the list.

Using curly braces which create a set, not a list.

input_variables must be a list of strings with variable names quoted.

4fill in blank

hard

Fill both blanks to create a PromptTemplate and format it with variables.

LangChain

from langchain import PromptTemplate

prompt = PromptTemplate(template=[1], input_variables=["animal", "sound"])
result = prompt.format(**[2])

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

A"The {animal} goes {sound}."

B{"animal": "dog", "sound": "woof"}

C"The animal goes sound."

D{"animal", "dog", "sound", "woof"}

Attempts:

3 left

💡 Hint

Common Mistakes

Passing a set instead of a dictionary to format.

Not using curly braces in the template string.

The template string must have placeholders, and format expects a dictionary with keys matching input_variables.

5fill in blank

hard

Fill all three blanks to create a PromptTemplate, format it, and print the result.

LangChain

from langchain import PromptTemplate

prompt = PromptTemplate(template=[1], input_variables=["city", "weather"])
result = prompt.format(**[2])
print([3])

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

A"The weather in {city} is {weather}."

B{"city": "Paris", "weather": "sunny"}

Cresult

D"The city is {city} and weather is {weather}."

Attempts:

3 left

💡 Hint

Common Mistakes

Printing the dictionary instead of the formatted result.

Not using curly braces in the template string.

The template string uses placeholders, format gets a dictionary, and print outputs the formatted string.

Practice

1. What is the main purpose of PromptTemplate in langchain?

easy

A. To create message templates with placeholders for dynamic content

B. To execute machine learning models directly

C. To store data in a database

D. To visualize data in charts

Solution

1. Step 1: Understand the role of PromptTemplate

   PromptTemplate is designed to create text templates that include placeholders for variables.

2. Step 2: Identify its main use

   It helps organize prompts by allowing you to fill in placeholders later, making prompt reuse easier.

3. Final Answer:

   To create message templates with placeholders for dynamic content -> Option A

4. Quick Check:

   PromptTemplate = Templates with placeholders [OK]

Hint: PromptTemplate = template with blanks to fill [OK]

Common Mistakes:

• Thinking PromptTemplate runs models
• Confusing it with data storage
• Assuming it creates visual charts

2. Which of the following is the correct way to create a PromptTemplate with a placeholder named name?

easy

A. PromptTemplate.from_template("Hello, <name>!")

B. PromptTemplate.from_template("Hello, $name!")

C. PromptTemplate.from_template("Hello, {name}!")

D. PromptTemplate.from_template("Hello, %name%!")

Solution

1. Step 1: Recall placeholder syntax in PromptTemplate

   Langchain uses curly braces {} to mark placeholders in templates.

2. Step 2: Match the syntax to the options

   Only PromptTemplate.from_template("Hello, {name}!") uses curly braces correctly: {name}.

3. Final Answer:

   PromptTemplate.from_template("Hello, {name}!") -> Option C

4. Quick Check:

   Placeholders use curly braces {} [OK]

Hint: Placeholders always use curly braces {} [OK]

Common Mistakes:

• Using $ or % instead of {} for placeholders
• Using angle brackets <> which are invalid
• Confusing placeholder syntax with other languages

3. Given the code:

from langchain.prompts import PromptTemplate
prompt = PromptTemplate.from_template("Hello, {name}!")
result = prompt.format(name="Alice")
print(result)

What will be printed?

medium

A. Hello, {name}!

B. Hello, Alice!

C. Hello, name!

D. Error: missing argument

Solution

1. Step 1: Understand the template and format method

   The template has a placeholder {name}. The format method fills it with the value "Alice".

2. Step 2: Determine the output of print(result)

   After formatting, the placeholder is replaced, so the output is "Hello, Alice!".

3. Final Answer:

   Hello, Alice! -> Option B

4. Quick Check:

   format() replaces {name} with "Alice" [OK]

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

Common Mistakes:

• Printing template without formatting
• Confusing placeholder name with literal text
• Expecting an error without missing arguments

4. What is the error in this code snippet?

from langchain.prompts import PromptTemplate
prompt = PromptTemplate.from_template("Hi, {user}!")
result = prompt.format(name="Bob")
print(result)

medium

A. KeyError because 'user' placeholder is not provided

B. No error; output is 'Hi, Bob!'

C. SyntaxError due to wrong placeholder syntax

D. TypeError because format() is missing arguments

Solution

1. Step 1: Check placeholder and format argument names

   The template uses {user} but format() provides name="Bob" which does not match.

2. Step 2: Understand the error caused

   Since {user} is not given a value, a KeyError occurs during formatting.

3. Final Answer:

   KeyError because 'user' placeholder is not provided -> Option A

4. Quick Check:

   Placeholder name must match format() keys [OK]

Hint: Placeholder and format keys must match exactly [OK]

Common Mistakes:

• Assuming format() keys can differ from placeholders
• Thinking it's a syntax error
• Expecting no error when keys mismatch

5. You want to create a PromptTemplate that asks for a user's name and age, then formats a greeting. Which code correctly defines and uses this template?

hard

A. prompt = PromptTemplate.from_template("Hello {name}, you are {age} years old.")
result = prompt.format(user="Eva", years=30)
print(result)

B. prompt = PromptTemplate.from_template("Hello {name}, you are {age} years old.")
result = prompt.format(name="Eva")
print(result)

C. prompt = PromptTemplate.from_template("Hello {name}, you are {age} years old.")
result = prompt.format("Eva", 30)
print(result)

D. prompt = PromptTemplate.from_template("Hello {name}, you are {age} years old.")
result = prompt.format(name="Eva", age=30)
print(result)

Solution

1. Step 1: Check template placeholders

   The template has placeholders {name} and {age} which must be provided as keyword arguments in format().

2. Step 2: Verify format() usage

   prompt = PromptTemplate.from_template("Hello {name}, you are {age} years old.") result = prompt.format(name="Eva", age=30) print(result) correctly passes name="Eva" and age=30 matching placeholders. Others miss arguments or use wrong keys or positional args.

3. Final Answer:

   Correctly defines and uses placeholders with matching keys -> Option D

4. Quick Check:

   Match placeholders and format() keys exactly [OK]

Hint: Pass all placeholders as keyword args in format() [OK]

Common Mistakes:

• Missing required placeholder arguments
• Using wrong argument names in format()
• Passing positional args instead of keywords