130 lines
4.9 KiB
Markdown
130 lines
4.9 KiB
Markdown
Data Forms
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==========
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[Back](index.md)
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Allows to exchange structured data between users and applications for common
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tasks such as registration and searching using Forms.
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* Create a Form to fill out
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* Answer a Form
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**XEP related:** [XEP-4](http://www.xmpp.org/extensions/xep-0004.html)
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Create a Form to fill out
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-------------------------
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**Description**
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An XMPP entity may need to gather data from another XMPP entity. Therefore,
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the data-gathering entity will need to create a new Form, specify the fields
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that will conform the Form and finally send the Form to the data-providing
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entity.
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**Usage**
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In order to create a Form to fill out use the _**Form**_'s constructor passing
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the constant **DataForm.type.form** as the parameter. The next step is to create
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the form fields and add them to the form. In order to create and customize a
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_**FormField**_ use the _**FormField**_'s constructor specifying the variable
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name of the field as the parameter. Then use **setType(String type)** to set
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the field's type (e.g. FormField.type.hidden, FormField.type.text_single).
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Once we have the _**Form**_ instance and the _**FormFields**_ the last step is
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to send **addField(FormField field)** for each field that we want to add to
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the form.
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Once the form to fill out is finished we will want to send it in a message.
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Send **getDataFormToSend()** to the form and add the answer as an extension to
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the message to send.
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**Examples**
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In this example we can see how to create and send a form to fill out:
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```
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// Create a new form to gather data
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Form formToSend = new Form(DataForm.type.form);
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formToSend.setInstructions(Fill out this form to report your case.\nThe case will be created automatically.");
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formToSend.setTitle("Case configurations");
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// Add a hidden variable to the form
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FormField field = new FormField("hidden_var");
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field.setType(FormField.type.hidden);
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field.addValue("Some value for the hidden variable");
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formToSend.addField(field);
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// Add a fixed variable to the form
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field = new FormField();
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field.addValue("Section 1: Case description");
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formToSend.addField(field);
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// Add a text-single variable to the form
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field = new FormField("name");
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field.setLabel("Enter a name for the case");
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field.setType(FormField.type.text_single);
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formToSend.addField(field);
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// Add a text-multi variable to the form
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field = new FormField("description");
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field.setLabel("Enter a description");
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field.setType(FormField.type.text_multi);
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formToSend.addField(field);
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// Create a chat with "user2@host.com"
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Chat chat = conn1.createChat("user2@host.com" );
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Message msg = chat.createMessage();
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msg.setBody("To enter a case please fill out this form and send it back");
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// Add the form to fill out to the message to send
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msg.addExtension(formToSend.getDataFormToSend());
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// Send the message with the form to fill out
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chat.sendMessage(msg);
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```
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Answer a Form
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-------------
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**Description**
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Under many situations an XMPP entity could receive a form to fill out. For
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example, some hosts may require to fill out a form in order to register new
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users. Smack lets the data-providing entity to complete the form in an easy
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way and send it back to the data-gathering entity.
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**Usage**
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The form to fill out contains useful information that could be used for
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rendering the form. But it cannot be used to actually complete it. Instead
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it's necessary to create a new form based on the original form whose purpose
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is to hold all the answers.
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In order to create a new _**Form**_ to complete based on the original
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_**Form**_ just send **createAnswerForm()** to the original _**Form**_. Once
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you have a valid form that could be actually completed all you have to do is
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send **setAnswer(String variable, String value)** to the form where variable
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is the variable of the _**FormField**_ that you want to answer and value is
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the String representation of the answer. If the answer consist of several
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values you could then use **setAnswer(String variable, List values)** where
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values is a List of Strings.
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Once the form has been completed we will want to send it back in a message.
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Send **getDataFormToSend()** to the form and add the answer as an extension to
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the message to send back.
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**Examples**
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In this example we can see how to retrieve a form to fill out, complete the
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form and send it back:
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```
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// Get the message with the form to fill out
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Message msg2 = chat2.nextMessage();
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// Retrieve the form to fill out from the message
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Form formToRespond = Form.getFormFrom(msg2);
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// Obtain the form to send with the replies
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Form completedForm = formToRespond.createAnswerForm();
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// Add the answers to the form
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completedForm.setAnswer("name", "Credit card number invalid");
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completedForm.setAnswer("description", "The ATM says that my credit card number is invalid");
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msg2 = chat2.createMessage();
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msg2.setBody("To enter a case please fill out this form and send it back"):
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// Add the completed form to the message to send back
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msg2.addExtension(completedForm.getDataFormToSend());
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// Send the message with the completed form
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chat2.sendMessage(msg2);
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```
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