Outputting specific categories with exp:channel:form

Question

I want my users to be able to post articles so I'm using channel:form to accomplish this, everything's working great but I can't work out how to output categories as checkboxes, I have two category groups that i'd like to output separately, the code i've tried either outputs all categories or none.

I have the following code:

{exp:channel:form channel="work" return="contribute/thanks"}
          <p>
            <label for="title">Title</label>
            <input type="text" name="title" id="title" value="{title}" size="50" maxlength="100" onkeyup="liveUrlTitle();">
            <input type="hidden" name="url_title" id="url_title" value="{url_title}" maxlength="75" size="50">
          </p>
<h2>Formats</h2>
          {categories}
            {if category_group_id == 4} {!-- formats --}
            <label class="checkbox">{category_name}
            <input type="checkbox" id="{category_id}" name="{category_id}[]" value="">
            </label>
            {/if}
          {/categories}

          <h2>Industries</h2>
          {categories}
            {if category_group_id == 1} {!-- industries --}
            <label class="checkbox">{category_name}
            <input type="checkbox" id="{category_id}" name="{category_id}[]" value="">
            </label>
            {/if}
          {/categories}

          <p><input type="submit" name="submit" value="Submit"></p>

{/exp:channel:form}

This isn't outputting any categories, seems it's not understanding the if statements? However if I use the code shown on the example (http://ellislab.com/expressionengine/user-guide/add-ons/channel/channel_form/#categories)

<label for="categories">Categories</label>
<select name="category[]" id="categories" size="4" multiple="multiple">
  {categories}
    <option value="{category_id}"{selected}>{category_name}</option>
  {/categories}
</select>

This outputs all of the categories into one select dropdown, i'm struggling to see how to adapt this, any ideas would be most appreciated!

Answer 1

First u can use (show_group) param in your {categories} loop instead off {if} condition

      {categories show_group="4"}
        ......
      {/categories}

      {categories show_group="1"}
        ......
      {/categories}

and if you want to use {if} condition then change your code to :

      {categories}
        {if {category_group_id} == 4} {!-- formats --}
        ......
        {/if}
      {/categories}

      {categories}
        {if {category_group_id} == 1} {!-- formats --}
        ......
        {/if}
      {/categories}

the trick here is to around category_group_id variable with parentheses.

Note: this hack is in EE2.8.0 in another version maybe the line number will be different.

Regard's.

Answer 2

Like this for category group with checkbox using Channel Form

  {categories show_group="5"}
    <label class="checkbox">{category_name}
    <input type="checkbox" id="{category_id}" name="category[]" value="{category_id}">
    </label><br />
  {/categories}

  {categories show_group="6"}
    <label class="checkbox">{category_name}
    <input type="checkbox" id="{category_id}" name="category[]" value="{category_id}" >
    </label><br />
  {/categories}