github.com/vugu/vugu@v0.3.5/vgform/select.go (about)

     1  package vgform
     2  
     3  import (
     4  	"errors"
     5  
     6  	"github.com/vugu/vugu"
     7  )
     8  
     9  // Select wraps an HTML select element.
    10  //
    11  // For clarity in naming: The word "value" refers to the value
    12  // of the currently selected option.  The word "key" refers to
    13  // the text inside the value attribute of an option tag, and the
    14  // word "text" refers to the HTML content of an option tag, i.e.
    15  // `<option value="some-key">some text</option>`.
    16  //
    17  // The Value field is a StringValuer which is used to get the current
    18  // value upon render, and update it when changed.
    19  // The StringPtr type provides a simple adapter for *string.
    20  //
    21  // NOTE: When slots are supported this will be updated to support
    22  // providing your own option tags so you can do things like
    23  // option groups.
    24  //
    25  // For the common case of simple lists of texts, set the Options
    26  // as appropriate.  See SliceOptions and MapOptions
    27  // for convenient adapters for []string and map[string]string.
    28  type Select struct {
    29  	Value StringValuer // get/set the currently selected value
    30  	// TODO: should we also just make a ValuePtr *string - which would let people
    31  	// do :ValuePtr="&c.SomeRegularString" - seems like some people will want the convenience
    32  	// TODO: multiple (will need a new field and a new type, StringSliceValuer?)
    33  
    34  	Options Options // provide KeyLister and TextMapper in one
    35  
    36  	AttrMap vugu.AttrMap // regular HTML attributes like id and class
    37  	// TODO: might make sense to refactor this AttrMap thing to work well
    38  	// with SetAttributeInterface and AttributeLister/vg-attr - perhaps a slice of attributes
    39  	// is better and for vg-attr we just append to the slice and for the
    40  	// others we us SetAttributeInterace (or some variation that uses the same
    41  	// logic but works on an list of attributes.)  A type AttributeList []VGAttribute
    42  	// might be in order.  Refactor to separate vgnode package might be appropriate...
    43  
    44  	// el     js.Value
    45  	keys   []string
    46  	curVal string
    47  }
    48  
    49  func (c *Select) buildKeys() []string {
    50  
    51  	// if c.el.IsUndefined() {
    52  	// 	panic(errors.New("Select should have c.el set"))
    53  	// }
    54  	if c.Value == nil {
    55  		panic(errors.New("Select.Value must not be nil"))
    56  	}
    57  	if c.Options == nil {
    58  		panic(errors.New("Select.Options must not be nil (TODO: when slots are supported that will be allowed instead of Options)"))
    59  	}
    60  
    61  	c.keys = c.Options.KeyList()
    62  	c.curVal = c.Value.StringValue()
    63  
    64  	return c.keys
    65  }
    66  
    67  func (c *Select) isOptSelected(k string) bool {
    68  	return c.curVal == k
    69  }
    70  
    71  func (c *Select) optText(k string) string {
    72  	return c.Options.TextMap(k)
    73  }
    74  
    75  func (c *Select) handlePopulate() {
    76  
    77  	// var buf bytes.Buffer
    78  	// buf.Grow(len(`<option value=""></option>`) * len(c.keys) * 2)
    79  	// for _, k := range c.keys {
    80  	// 	buf.WriteString(`<option value="`)
    81  	// 	buf.WriteString(html.EscapeString(k))
    82  	// 	buf.WriteString(`">`)
    83  	// 	buf.WriteString(html.EscapeString(c.Options.TextMap(k)))
    84  	// 	buf.WriteString(`</option>`)
    85  	// }
    86  	// c.el.Set("innerHTML", buf.String())
    87  
    88  	// see if we need this...
    89  	// v := c.curVal
    90  	// idx := -1
    91  	// for i, k := range c.keys {
    92  	// 	if k == v {
    93  	// 		idx = i
    94  	// 	}
    95  	// }
    96  
    97  	// c.el.Set("selectedIndex", idx)
    98  
    99  }
   100  
   101  func (c *Select) handleChange(event vugu.DOMEvent) {
   102  
   103  	newVal := event.PropString("target", "value")
   104  	c.curVal = newVal // why not
   105  	c.Value.SetStringValue(newVal)
   106  
   107  }