Accept typed input

A how-to guide: a form the reader types into, one field or several, finished with RETURN.

from sextile import OnOneFrame, Page, PageAddress, PageLayout, PageRequest, PageRouter, Sextile
from sextile.forms import Field, FieldSet

router = PageRouter()

@router.page("1", name="signin", title="Sign in")
async def signin(request: PageRequest) -> Page:
    form = FieldSet(
        fields=[Field(name="name", label="NAME", row=0, accepts=str.isalpha, width=12, hint=" your name", hint_row=1)],
        on_submit=lambda values: PageAddress("2") if values["name"] else None,
        submit_label="sign in",
    )
    return PageLayout(parts=[OnOneFrame(form)]).build(request)

app = Sextile(name="Desk", pages=[*router])

 SIGN IN                              1a
  
 NAME   ADA            # sign in        
  your name                             
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
  
 TAB next field, DEL rub out, 0 index   

A FieldSet owns some rows of the frame: each Field has a label, an accepts predicate saying what belongs in it, a width, and a hint drawn beneath it. on_submit is asked the keyed values whenever the form is drawn and returns where RETURN leads, or None while there is nowhere to go — so the # sign in mark appears only once the form can be submitted.

Two or more fields are moved between with TAB, and a footnote says something about what has been keyed so far:

from sextile import OnOneFrame, Page, PageAddress, PageLayout, PageRequest, PageRouter, Sextile
from sextile.forms import Field, FieldSet

router = PageRouter()

@router.page("1", name="signin", title="Sign in")
async def signin(request: PageRequest) -> Page:
    async def whole(values: dict[str, str]) -> str:
        return f"{values['first']} {values['last']}".strip()
    form = FieldSet(
        fields=[
            Field(name="first", label="FIRST", row=0, accepts=str.isalpha, width=10),
            Field(name="last", label="LAST", row=2, accepts=str.isalpha, width=10),
        ],
        on_submit=lambda values: PageAddress("2") if values["first"] and values["last"] else None,
        footnote=whole, footnote_row=4, submit_label="sign in",
    )
    return PageLayout(parts=[OnOneFrame(form)]).build(request)

app = Sextile(name="Desk", pages=[*router])

 SIGN IN                              1a
  
 FIRST   ADA                            
                                        
 LAST    LOVELACE     # sign in         
                                        
 ADA LOVELACE                           
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
                                        
  
 TAB next field, DEL rub out, 0 index   

A field takes digits as data — a nought keyed into it is a nought — so a page carrying a form cannot offer 0 for the index. Name a way out in the footer instead, with the FieldSet’s footer_items.

The form API is sextile.forms; why a form is a menu whose choices change, and why a digit chooses while a letter types, is in Design decisions. For a field with matches beneath it, see Type-ahead completion.