// NewPager returns a new *Pager instance. Note that the
// Context must satisfy the conditions mentioned in the
// Pager type documentation. Otherwise an error will be
// returned.
func NewPager(ctx *app.Context) (*Pager, error) {
name := ctx.HandlerName()
if name == "" {
return nil, errors.New("can't generate a pager from an unnamed handler")
}
names := ctx.Provider().ParamNames()
if len(names) == 0 {
return nil, errors.New("can't generate a pager from a handler with no parameters, must have a page parameter")
}
if names[len(names)-1] != "page" {
return nil, fmt.Errorf("last named parameter is %q, not page", names[len(names)-1])
}
params := make([]interface{}, ctx.Count()-1)
for ii := 0; ii < ctx.Count()-1; ii++ {
params[ii] = ctx.IndexValue(ii)
}
return &Pager{
Name: name,
Parameters: params,
Ctx: ctx,
}, nil
}