in a Jinja2 template like "Tell me something: {{s}}", and with s as a bytes value like s = b"foo", the rendered template will look like "Tell me something: b'foo'". How do I avoid this behavior?

Using filters or preprocessing the data does not help in my case, because I'd like to use jinja2 as a building block of something else, and I don't have full control of the input data and of the templates. I am pretty sure this will become an extremely common mistake in my application so I'd like to prevent that.

The desired behavior is that:

1. Jinja2 throws an error if someone tries to render bytes
2. Alternatively, Jinja2 automatically converts the bytes to strings using decode("utf8"), but I'd prefer the former.

in a Jinja2 template like "Tell me something: {{s}}", and with s as a bytes value like s = b"foo", the rendered template will look like "Tell me something: b'foo'". How do I avoid this behavior?

Using filters or preprocessing the data does not help in my case, because I'd like to use jinja2 as a building block of something else, and I don't have full control of the input data and of the templates. I am pretty sure this will become an extremely common mistake in my application so I'd like to prevent that.

The desired behavior is that:

1. Jinja2 throws an error if someone tries to render bytes
2. Alternatively, Jinja2 automatically converts the bytes to strings using decode("utf8"), but I'd prefer the former.

• jinja2

1 Answer 1

Although jinja2 doesn't offer a direct way to test if a variable is a bytes object rather than a string, one easy workaround is to concatenate the variable with an empty string to raise a TypeError: can't concat str to bytes when given a bytes object:

Tell me something: {{ s + '' }}