understanding the arguments in the textInput.typeahead function in ShinySky for Shiny

Question

I know I am asking a question about an R package that isn't super well know (only has 5 tags...one of which is from my previous question), but I'm still hoping I can open up a discussion here.

I have read the documentation for the textinput.typeahead in the Shinysky package. However, the documentation leaves quite a few questions open.

I'm doing my best to figure out how to use this by following the example:

textInput.typeahead(
        id="thti"
        ,placeholder="type 'name' or '2'"
        ,local=data.frame(name=c("name1","name2"),info=c("info1","info2"))
        ,valueKey = "name"
        ,tokens=c(1,2)
        ,template = HTML("<p class='repo-language'>{{info}}</p> <p class='repo-name'>{{name}}</p> <p class='repo-description'>You need to learn more CSS to customize this further</p>")

Usage

textInput.typeahead(id, placeholder, local, valueKey, tokens, template, limit = 20)

updateTextInput.typeahead(session, id, dataset, valueKey, tokens, template, limit = 20, placeholder = "")

First question: There is no discussion about what the difference between these two methods actually do. What's the difference, and why would someone want to pick one instead of the other?

Arguments

tokens
A list whose length equal to nrow(local) where each element is array of string tokens. Typing the tokens will select the correponding rows

The first thing that pops out here (aside from the misspelling of 'corresponding') is that tokens is supposed to be a list. But when I look at the example provided here, the argument reads ,tokens=c(1,2). This is a vector, not a list.

Even if a vector is ok, I'm not so sure what this does. Typing the tokens will select the correponding rows. Does this somehow mean that I would have to explicitly tell shinysky where to look in order to populate the typeahead?

template
A hogan template on how to show the content e.g. '< p > name < / p >' where name is one of the variables in local

So not only do I need to show typeahead where to look among the rows using a list or vector, but I need to show it which column to look into. Is this correct? If so, why does the example show 2 column names: {info} and {name}?

limit
An integer of the upper limit on how many hits to show in the typeahead dropdown

How does this affect the memory demands of loading all the values into the typeahead?

Anyway, thanks for reading this far. I hope we can figure out how to best use this tool in this package.

Answer 1

Here are my understanding:

1. textInput.typeahead vs updateTextInput.typeahead

This is the same as textInput and updateTextInput, one is to initialize a new input, the other is to update an existing input

2. Token

Yes it accepts a vector. I think this is like a shortcut or rowname to each row of the data frame. So if you type the rowname (or row number), it displays the row you want.

3. Template

You can customize what is displayed in the prompt box for each row of your data. So the example here will only display name column, but you can choose to display any column you like

4. Limit

This probably just controls the number of rows to display. I would imagine all data frame needs to be in the memory.