14.3 Forms

In web development, the following workflow will probably look quite familiar:

Open a web page showing a form
Users fill out and submit the form
If a user submits some invalid information or has neglected to fill out a required field, the form will be returned to the user (along with the filled in data) with some descriptive information about the problem.
Users re-fill the invalid fields and continue attempting to submit the form until it's accepted

At the receiving end, the script must:

Check the user submitted form data.
Verify whether the data is the correct type and of the appropriate standard. For example, if a username is submitted, it must verify that it contains only valid characters. Other examples would be checking for minimum and maximum lengths, username uniqueness, and so on.
Filtering data and cleaning up unsafe characters to guarantee that our application only processes data which is safe.
If necessary, pre-format the data (or data gaps need to be cleared through the HTML coding and so on.)
Prepare the data for insertion into the database

Although the procedure is not very complex, it usually requires a lot of boilerplate. In addition, web applications often use a variety of different control structures to display error messages on returned pages. Implementing form validation is a simple but boring task.

Forms and validation

For developers, the general development process is very complex, and mostly are repeating the same work. Assuming a scenario project suddenly need to add a form data, then the local code of the entire process needs to be modified. We know that Go inside a struct is a common data structure, so beego the form struct used to process form information.

First define a developing Web applications corresponding struct, a field corresponds to a form element, through the struct tag to define the corresponding element information and authentication information, as follows:

type User struct{
	Username 	string 	`form:text,valid:required`
	Nickname 	string 	`form:text,valid:required`
	Age			int 	`form:text,valid:required|numeric`
	Email 		string 	`form:text,valid:required|valid_email`
	Introduce 	string 	`form:textarea`
}

Struct defined in this way after the next operation in the controller

func (this *AddController) Get() {
	this.Data["form"] = beego.Form(&User{})
	this.Layout = "admin/layout.html"
	this.TplNames = "admin/add.tpl"
}

This form is displayed in the template

<h1>New Blog Post</h1>
<form action="" method="post">
{{.form.render()}}
</form>

Above we defined the entire first step to display the form from the struct process, the next step is the user fill out the information, and then verify that the server receives data, and finally into the database.

func (this *AddController) Post() {
	var user User
	form := this.GetInput(&user)
	if !form.Validates() {
		return 
	}
	models.UserInsert(&user)
	this.Ctx.Redirect(302, "/admin/index")
}

Form type

The following list to the corresponding form element information:

<table cellpadding="0" cellspacing="1" border="0" style="width:100%" class="tableborder">
  <tbody>
	<tr>
	  <th>Name</th>
	  <th>parameter</th>
	  <th>Description</th>
	</tr>
	<tr>
	  <td class="td"><strong>text</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">textbox input box</td>
	</tr>

	<tr>
	  <td class="td"><strong>button</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">button</td>
	</tr>

	<tr>
	  <td class="td"><strong>checkbox</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">multi-select box</td>
	</tr>

	<tr>
	  <td class="td"><strong>dropdown</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">drop-down selection box</td>
	</tr>

	<tr>
	  <td class="td"><strong>file</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">file upload</td>
	</tr>

	<tr>
	  <td class="td"><strong>hidden</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">hidden elements</td>
	</tr>

	<tr>
	  <td class="td"><strong>password</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">password input box</td>
	</tr>

	<tr>
	  <td class="td"><strong>radio</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">single box</td>
	</tr>

	<tr>
	  <td class="td"><strong>textarea</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">text input box</td>
	</tr>
  </tbody>
</table>

Forms authentication

The following list may be used are listed rules native:

<table cellpadding="0" cellspacing="1" border="0" style="width:100%" class="tableborder">
  <tbody>
	<tr>
	  <th>rules</th>
	  <th>parameter</th>
	  <th>Description</th>
	  <th>Example</th>
	</tr>

	<tr>
	  <td class="td"><strong>required</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">If the element is empty, it returns FALSE</td>
	  <td class="td"></td>
	</tr>

	<tr>
	  <td class="td"><strong>matches</strong>
	  </td>
	  <td class="td">Yes</td>
	  <td class="td">if the form element's value with the corresponding form field parameter values are not equal, then return
		FALSE</td>
	  <td class="td">matches [form_item]</td>
	</tr>

	
	<tr>
	  
	  <td class="td"><strong>is_unique</strong>
	  </td>
	  
	  <td class="td">Yes</td>
	  
	  <td class="td">if the form element's value with the specified field in a table have duplicate data, it returns False( Translator's
		Note: For example is_unique [User.Email], then the validation class will look for the User table in the
		Email field there is no form elements with the same value, such as deposit repeat, it returns false, so
		developers do not have to write another Callback verification code.)</td>
	  
	  <td class="td">is_unique [table.field]</td>
	  </tr>

	<tr>
	  <td class="td"><strong>min_length</strong>
	  </td>
	  <td class="td">Yes</td>
	  <td class="td">form element values if the character length is less than the number defined parameters, it returns FALSE</td>
	  <td class="td">min_length [6]</td>
	</tr>

	<tr>
	  <td class="td"><strong>max_length</strong>
	  </td>
	  <td class="td">Yes</td>
	  <td class="td">if the form element's value is greater than the length of the character defined numeric argument, it returns
		FALSE</td>
	  <td class="td">max_length [12]</td>
	</tr>

	<tr>
	  <td class="td"><strong>exact_length</strong>
	  </td>
	  <td class="td">Yes</td>
	  <td class="td">if the form element values and parameters defined character length number does not match, it returns FALSE</td>
	  <td class="td">exact_length [8]</td>
	</tr>

	
	<tr>
	  
	  <td class="td"><strong>greater_than</strong>
	  </td>
	  
	  <td class="td">Yes</td>
	  
	  <td class="td">If the form element values non- numeric types, or less than the value defined parameters, it returns FALSE</td>
	  
	  <td class="td">greater_than [8]</td>
	  </tr>

	
	<tr>
	  
	  <td class="td"><strong>less_than</strong>
	  </td>
	  
	  <td class="td">Yes</td>
	  
	  <td class="td">If the form element values non- numeric types, or greater than the value defined parameters, it returns FALSE</td>
	  
	  <td class="td">less_than [8]</td>
	  </tr>

	<tr>
	  <td class="td"><strong>alpha</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">If the form element value contains characters other than letters besides, it returns FALSE</td>
	  <td class="td"></td>
	</tr>

	<tr>
	  <td class="td"><strong>alpha_numeric</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">If the form element values contained in addition to letters and other characters other than numbers, it returns
		FALSE</td>
	  <td class="td"></td>
	</tr>

	<tr>
	  <td class="td"><strong>alpha_dash</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">If the form element value contains in addition to the letter/ number/ underline/ characters other than dash,
		returns FALSE</td>
	  <td class="td"></td>
	</tr>

	<tr>
	  <td class="td"><strong>numeric</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">If the form element value contains characters other than numbers in addition, it returns FALSE</td>
	  <td class="td"></td>
	</tr>

	<tr>
	  <td class="td"><strong>integer</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">except if the form element contains characters other than an integer, it returns FALSE</td>
	  <td class="td"></td>
	</tr>

	
	<tr>
	  
	  <td class="td"><strong>decimal</strong>
	  </td>
	  
	  <td class="td">Yes</td>
	  
	  <td class="td">If the form element type( non- decimal ) is not complete, it returns FALSE</td>
	  
	  <td class="td"></td>
	  </tr>

	<tr>
	  <td class="td"><strong>is_natural</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">value if the form element contains a number of other unnatural values ( other values excluding zero ), it
		returns FALSE. Natural numbers like this: 0,1,2,3.... and so on.</td>
	  <td class="td"></td>
	</tr>

	<tr>
	  <td class="td"><strong>is_natural_no_zero</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">value if the form element contains a number of other unnatural values ( other values including zero ), it
		returns FALSE. Nonzero natural numbers: 1,2,3..... and so on.</td>
	  <td class="td"></td>
	</tr>

	<tr>
	  <td class="td"><strong>valid_email</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">If the form element value contains invalid email address, it returns FALSE</td>
	  <td class="td"></td>
	</tr>

	<tr>
	  <td class="td"><strong>valid_emails</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">form element values if any one value contains invalid email address( addresses separated by commas in English
		), it returns FALSE.</td>
	  <td class="td"></td>
	</tr>

	<tr>
	  <td class="td"><strong>valid_ip</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">if the form element's value is not a valid IP address, it returns FALSE.</td>
	  <td class="td"></td>
	</tr>

	<tr>
	  <td class="td"><strong>valid_base64</strong>
	  </td>
	  <td class="td">No</td>
	  <td class="td">if the form element's value contains the base64-encoded characters in addition to other than the characters,
		returns FALSE.</td>
	  <td class="td"></td>
	</tr>

  </tbody>
</table>

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14.3 Forms

Forms and validation

Form type

Forms authentication

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