ComfyUI Node: Evaluate Strings

Evaluate Strings:

The Evaluate Strings node is designed to dynamically evaluate Python expressions involving string variables. This node allows you to input a Python expression and optional string variables, which it then evaluates to produce a resultant string. It is particularly useful for AI artists who need to manipulate and combine text dynamically within their workflows. The node can also print the evaluation process and results to the console for debugging purposes, making it easier to understand how the input variables are being processed and combined.

Evaluate Strings Input Parameters:

python_expression

This parameter accepts a Python expression in the form of a string. The expression can include variables such as a, b, and c, which will be evaluated to produce the final result. The default value is "a + b + c", and it is not multiline, meaning it should be a single line of code. This parameter is crucial as it defines the logic for how the input strings will be combined or manipulated.

print_to_console

This parameter is a boolean option that determines whether the evaluation process and results should be printed to the console. It accepts two values: "False" and "True", with the default being "False". When set to "True", it helps in debugging by displaying the input variables and the evaluated result in the console.

a

This optional parameter is a string variable that can be used within the python_expression. The default value is "Hello", and it is not multiline. This parameter allows you to provide a custom string that will be used in the evaluation process.

b

This optional parameter is a string variable similar to a. The default value is " World", and it is not multiline. It provides additional flexibility by allowing you to include another custom string in the evaluation.

c

This optional parameter is another string variable that can be used in the python_expression. The default value is "!", and it is not multiline. This parameter further extends the capability to include more custom strings in the evaluation.

Evaluate Strings Output Parameters:

STRING

The output of this node is a single string that results from the evaluation of the provided python_expression using the input variables a, b, and c. This output is crucial as it represents the final combined or manipulated text based on the logic defined in the python_expression.

Evaluate Strings Usage Tips:

• Use the print_to_console option set to "True" for debugging purposes to see the input variables and the evaluated result in the console.
• Customize the python_expression to perform various string manipulations such as concatenation, slicing, or formatting to suit your specific needs.
• Utilize the optional parameters a, b, and c to dynamically change parts of the expression without modifying the main logic.

Evaluate Strings Common Errors and Solutions:

NameError: name 'x' is not defined

• Explanation: This error occurs when the python_expression contains a variable that has not been defined or passed as an input parameter.
• Solution: Ensure that all variables used in the python_expression are defined and passed as input parameters.

SyntaxError: invalid syntax

• Explanation: This error occurs when the python_expression contains a syntax error.
• Solution: Double-check the syntax of your python_expression to ensure it is a valid Python expression.

TypeError: can only concatenate str (not "int") to str

• Explanation: This error occurs when trying to concatenate a string with a non-string type, such as an integer.
• Solution: Ensure that all variables used in string concatenation are of type string. You can use the str() function to convert other types to strings.