Form validation example for expressjs

example.js

    server.all('/admin/content/add_article',function(req,res)                                          
    {                                                                                                  
        server.form('post',req,res,function(form) {                                                    
            form.required('title')                                                                     
            form.optional('tags')                                                                      
            form.required('slug')                                                                      
            form.required('body')                                                                      
                                                                                                       
            form.valid(function(form) {                                                                
                res.send('Creating blog post titled : ' + form.values.title)                           
            })                                                                                         
                                                                                                       
            form.invalid(function(form) {                                                              
                form.render(res,'admin/add_article.html')                                              
            })                                                                                         
        })                                                                                             
    })

form.express.js

/* form validation for expressjs */

function validate(form,ctx) {
    valid = true
    for(var idx in form._required_fields) {
        x = form._required_fields[idx]
        if(form.values[x] == '') {            
            ctx["validation"][form._name][x] = x + " required"
            valid = false
        }
        ctx[form._name][x] = form.values[x]
    }
    
    return valid
}

function parse_form(f,req,name){

    objs = new Array()
    for(var x in req.body[name]) {
        objs.push( x )
    }

    f.values = {}
    for(var x in req.body[name]) {
        f.values[x] = req.body[name][x]        
    }

}


function form(formName, req, res, fn){

    o = {}
    o._name = formName
    o._required_fields = []
    o._optional_fields = []

    o.required = function(name){
        o._required_fields.push(name)
    }

    o.optional = function(name) {
        o._optional_fields.push(name)
    }

    o.render = function(res,template) {
        ctx = o.ctx
        res.render(template,ctx)
    }

    o.ctx = {}

    o.valid = function(fn) { o._valid_fn = fn }
    o.invalid = function(fn) { o._invalid_fn = fn }
 
    fn(o)

    o.ctx["validation"] = {}
    o.ctx["validation"][formName] = {}
    o.ctx[formName] = {}
        for(var x in o._required_fields) {
            val = o._required_fields[x]
            o.ctx["validation"][formName][val] = ""
            o.ctx[formName][val] = ""
        }
        for(var x in o._optional_fields) {
            val = o._optional_fields[x]
            o.ctx["validation"][formName][val] = ""
            o.ctx[formName][val] = ""
        }

    o.values = {}

    if(req.method == 'GET') {
        o._invalid_fn(o)
        return
    }else if(req.method == 'POST') {// OR PUT,DELETE, etc
        parse_form(o,req,o._name)
        if(validate(o,o.ctx)) {
            o._valid_fn(o) 
        }else{
            o._invalid_fn(o)
        }
    }
}

module.exports = form

template.html

<p> 
    <form method="POST" >
        <p>Title</p>        
        <input type="text" name="post[title]" value="${post.title}"/>
        ${ validation.post.title } 
    
        <p>Tags</p>         
        <input type="text" name="post[tags]" value="${post.tags}"/>
        ${ validation.post.tags }

        <p>Slug</p>
        <input type="text" name="post[slug]" value="${post.slug}"/>
        ${ validation.post.slug } 

        <p>Body ${ validation.post.body } </p>
        <textarea rows="30" cols="200" name="post[body]">${post.body}</textarea>

        <br/>
        <input type="submit" value="Save" name="action"/>
        <input type="submit" value="Preview" name="action"/>

    </form>
</p>