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From Apache Wiki <>
Subject [Couchdb Wiki] Update of "Working_with_Forms" by DaveCottlehuber
Date Thu, 28 Jun 2012 11:19:01 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Couchdb Wiki" for change notification.

The "Working_with_Forms" page has been changed by DaveCottlehuber:

Working with HTML forms and document update handlers

New page:


CouchDB supports HTML forms in a number of ways. Some useful HTML5 references are [[|html5rocks]]
and the definitive [[|Forms in HTML]] and
[[|the Form element]].

== Forms without client-side Javascript ==

A standard form and submit can be handled by CouchDB by using [[Document_Update_Handlers]]
to capture and process the POSTed data.

=== A minimal HTML5 form ===

<!DOCTYPE html>

<html lang="en">
  <meta charset="utf-8">
  <title>Minimal Form</title>

  <div id="contact-form">
    <form id="contact" method="post" action="/db/_design/ddoc/_update/simpleform">
        <label for="name">name</label>    <input type="text" name="name" placeholder="Full
Name" title="Enter your name" class="required">
        <label for="phone">phone</label>  <input type="tel" name="phone" placeholder="+1
(555) 555-5555" required="" pattern="\+?[0-9 )(-]+">
        <label for="email">e-mail</label> <input type="email" name="email"
placeholder="" title="e-mail address" class="required email">
        <label for="blog">blog</label>    <input type="url" name="url" placeholder="http://">
        <label for="message">message</label>
        <textarea name="message"></textarea>
        <input type="submit" name="submit" class="button" id="submit" value="submit">

The most important part of the above form is the {{{action="/simpleform/_design/simpleform/_update/simpleform"}}}
which specifies the update handler that will receive the POSTed data.

It's broken down into 5 key sections:

 * the Database {{{db}}}
 * the id of the design doc {{{_design/simpleform}}} itself
 * {{{_update}}} informs CouchDB that this is an update handler and specifies the key within
the ddoc that has our handler function
 * the final {{{simpleform}}} specifies the update handler name within that ddoc, that will
receive the POSTed data

=== Submitting the form from the terminal ===

Likely you'll be fiddling with your form quite a bit while working on the update handler.
In this case it makes a lot of sense simply to drive the form directly from the command line.
There is more information at [[Commandline_CouchDB]], including Windows tips.

curl -vX POST http://localhost:5984/simpleform/_design/simpleform/_update/simpleform \
    --header Content-Type:application/x-www-form-urlencoded \
    --data-urlencode name="John Doe" \
    --data-urlencode email="" \
    --data-urlencode phone="+1 (234) 567-890" \
    --data-urlencode url="" \
    --data-urlencode message="Y U NO HAZ CHEESBURGER" \
    --data-urlencode submit="submit"

If you are on a unix-like system, you may enjoy the colour output afforded by [[|httpie]],
a python-based curl replacement:

http --pretty --verbose --style fruity --form \
    post http://localhost:5984/simpleform/_design/simpleform/_update/simpleform  \
    name="John Doe" \
    email="" \
    phone="+1 (234) 567-890" \
    url="" \
    message="Y U NO HAZ CHEESBURGER" \

=== A basic update handler ===

Here's a simple update handler that will receive the POSTed data as second parameter, and
the previous document version if any as the first parameter . In our case, using POST, there
will be no existing document so this will always be {{{null}}}. Finally this function, to
help us debug the handler, conveniently returns the output of the new document, along with
the request and previous doc if any. Obviously this could be HTML or a redirect to another
page using custom headers, you will need to customise this to fit.

function(previous, request) {

    /* during development and testing you can write data to couch.log
     log({"previous": previous})
     log({"request": request})

    var doc = {}

    if (!previous) {
        // there's no existing document _id as we are not using PUT
        // let's use the email address as the _id instead
        if (request.form && {
            // Extract the JSON-parsed form from the request
            // and add in the user's email as docid
           doc     = request.form
           doc._id =
     var resp =  {
        'headers' : {
          'Content-Type' : 'application/json'
        'body' : toJSON({"request": request, "previous": previous, "doc": doc})
    return [doc, resp]

=== Tips and Tricks ===

There are a few points to cover here:

 * you can use {{{log(…)}}} to write data to your couch.log file
 * Note that there's only ever going to be additional data in the previous document if we
use a PUT request and provide a URL that includes the document {{{_id}}}. The POST approach
doesn't pass a new {{{_id}}} in so in our example this will be blank. However the same update
handler can be used to service multiple forms and HTTP verbs.
 * You must guard all tests {{{if (request.form && …}}} otherwise an exception will
occur if a field is missing, and your document will not be written.
 * The returned {{{request}}} object also conveniently includes a valid CouchDB {{{UUID}}}
if you do not generate one of your own.
 * When the function returns, if {{{doc}}} is empty then no data is written to CouchDB.
 * The update handler can return almost anything, including custom headers and body. See [[Document_Update_Handlers]]
for more information.

=== Results from the form ===

After filling out the form and POSTing it back, you'll receive the results from {{{toJSON}}}
in your browser. You can use firebug or chrome developer tools to view the resulting text
in a pretty JSON format, or copy and paste it into a terminal and use any of the JSON prettifiers
out there, such as [[|yajl]], which also has a {{{json_reformat}}}
command distributed with it.

Let's take a look in more detail over the three sections returned. The first section {{{}}}
is simply the current DB information, identical to {{{GET $COUCH/db_name}}}.

  request: {
    info: {
      db_name: "simpleform",
      doc_count: 3,
      doc_del_count: 0,
      update_seq: 32,
      purge_seq: 0,
      compact_running: false,
      disk_size: 340069,
      data_size: 158491,
      instance_start_time: "1340837365780629",
      disk_format_version: 6,
      committed_update_seq: 32

 * Next comes the {{{_id}}} of the previous document version, for example if we were doing
a PUT request, this would be filled, along with a {{{_rev}}} revision as well.
  * The requested path is provided in several forms, to make it easier to match update handlers
with document rewrite rules.
  * If any {{{query}}} parameters were passsed to the URL, they would also be accessible.
  * The full headers are available as usual.

    id: null,
    uuid: "8363428f19b4bc21217044e2b30133ad",
    method: "POST",
    requested_path: ["simpleform", "_design", "simpleform", "_update", "simpleform"],
    path: ["simpleform", "_design", "simpleform", "_update", "simpleform"],
    raw_path: "/simpleform/_design/simpleform/_update/simpleform",
    query: {},
    headers: {
      Accept: "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
      Accept - Charset: "ISO-8859-1,utf-8;q=0.7,*;q=0.3",
      Accept - Encoding: "gzip,deflate,sdch",
      Accept - Language: "en-US,en;q=0.8",
      Cache - Control: "max-age=0",
      Connection: "keep-alive",
      Content - Length: "150",
      Content - Type: "application/x-www-form-urlencoded",
      Host: "localhost:5984",
      Origin: "http://localhost:5984",
      Referer: "http://localhost:5984/simpleform/_design/simpleform/minimalform.html",
      User - Agent: "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_4) AppleWebKit/537.1 (KHTML,
like Gecko) Chrome/22.0.1188.0 Safari/537.1"

  * The original HTTP {{{body}}} is provided, as well as the originating {{{peer}}} IP address.
  * The url-encoded form parameters have conveniently been extracted and unencoded into a
JS object, which was stringified in our final {{{return}}}. This {{{form}}} is typically used
or transformed in some way to build up the resulting document object inside the update handler

    body: "name=John+Doe&phone=%2B1+%28234%29+987-654&",
    peer: "",
    form: {
      name: "John Doe",
      phone: "+1 (234) 987-654",
      email: "",
      url: "",
      message: "STILL NO CHEEZBURGER?",
      submit: "submit",
      _id: ""
  * {{{cookie}}} and {{{user context}}} are also available here, enabling such things are
inserting usernames, or checking roles before further processing. Ensure that you are not
duplicating functionality that should be in a [[Document_Update_Validation]] function.
  * the previous document is empty as we are doing a POST request.
    cookie: {},
    userCtx: {
      db: "simpleform",
      name: null,
      roles: []
    secObj: {}
  previous: null,

=== Emitting the result during testing ===

Finally we emit the resulting document, after our server-side update handler has run. Note
that the revision {{{_rev}}} is not yet available.
  doc: {
    name: "John Doe",
    phone: "+1 (234) 987-654",
    email: "",
    url: "",
    message: "STILL NO CHEEZBURGER?",
    submit: "submit",
    _id: ""

== Retrieve the Document ==

After the write was successful we can retrieve the new document:

$ curl --silent -HContent-Type:application/json  -vXGET $DB/ | json_reformat

* About to connect() to localhost port 5984 (#0)
*   Trying ::1... Connection refused
*   Trying connected
* Connected to localhost ( port 5984 (#0)
> GET /simpleform/ HTTP/1.1
> User-Agent: curl/7.21.4 (universal-apple-darwin11.0) libcurl/7.21.4 OpenSSL/0.9.8r zlib/1.2.5
> Host: localhost:5984
> Accept: */*
> Content-Type:application/json
< HTTP/1.1 200 OK
< Server: CouchDB/1.2.0 (Erlang OTP/R15B01)
< ETag: "1-389cd40f8d8317427a9d7ee9c24a0c81"
< Date: Thu, 28 Jun 2012 11:13:34 GMT
< Content-Type: text/plain; charset=utf-8
< Content-Length: 237
< Cache-Control: must-revalidate
{ [data not shown]
* Connection #0 to host localhost left intact
* Closing connection #0
    "_id": "",
    "_rev": "1-389cd40f8d8317427a9d7ee9c24a0c81",
    "form": {
        "name": "John Doe",
        "phone": "+1 (234) 987-654",
        "email": "",
        "url": "",
        "message": "STILL NO CHEEZBURGER?",
        "submit": "submit"

With the basic update handler above you should have no trouble modifying it further to perform
redirects, extract/merge or modify the data available to you - new and old document versions,
and user/security context as well. Don't forget that some code is better in a [[Document_Update_Validation]]
rather than in the update handler. The update handler will always act as another HTTP POST/PUT,
just run conveniently inside the server. They can still suffer from document conflicts, for

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