Hello,
I want to open composer on button click which will have an input field and whatever the value in the input field I will fetch data and then I will create a topic by filling fetched data.
Can someone guide me how can I create a custom form in composer?
You can take a look at
I believe it should fit your use case at a low level 
If you are going to be fetching data from a custom API, you may need a custom plugin / theme.
It’s a great feature but it doesn’t full fill my requirement. I can see this is creating template and that plugged in create topic form which is different. But, I want to display an input tag in composer and while saving or submitting the form. I have to create a topic with some data. Basically, It will render two composer one by one first with input tag and then it wil render create topic form composer with pre-filled data which I will pass from first composer.
Yeah, I am doing this in custom-theme but I am not able to render an input tag in composer. I am looking for an way to do it.
What if you set a minimum tag requirement for posts in that category?
It is generating a template per category but I want to display the input tag/html in composer regardless of category. It should be in general, when I click on button I should be rendering the form and when I submit the form then I should be pre-filling the data in the create topic form.
If I am understanding correctly. This Plugin might be what you’re looking for
This plugin might also help you as an alternative.