用猫鼬渲染额外的数据会导致车把

Question

Say I have a function which finds all open bets in a collection:

app.get('/profile/bet-history', function(req, res, next){
        var user = req.user;
        if(user){
            Bet.find({$query : {"username" : user.username, "settled":false, "paired" : true}, $orderby : {_id : -1}})
                .then(function(doc){
                    res.render('profile/bet-history', {bets: doc, user: req.user}); 
            });
        }else{
            res.redirect('/login');
        }
    });

And I have a Handlebars template which renders the above bets and user data:

<tbody>
    {{#if bets}}
        {{#each bets}}
            <tr>
                <td>{{date this.createdAt}}</td>
                <td>{{this.market}}({{this.bet}})</td>
                <td>{{this.stake}}</td>
                <td>{{this.odds}}</td>
                <td>{{render the potential returns here}}</td>
            </tr>
        {{/each}}
    {{else}}
        <tr>
            <td>
                <p>You have no matched bets. Please come back later.</p>
            </td>
        </tr>
    {{/if}}        
</tbody>

I want to perform a quick "potential returns" calculation on each individual result returned from .find() by calling some function calcReturns() which takes in the returned bet and multiplies the stake by the odds and then rendering that result of the function with the data returned by the .find() call, which is rendered in an {{#each}} partial. A key requirement is I want to use a function in an external .js file and I don't want to have to use another field in the Mongo database.

Answer 1

You could calculate the potential returns locally after the bets have been retrieved from the database.

app.get('/profile/bet-history', function(req, res, next){
        var user = req.user;
        if(user){
            Bet.find({$query : {"username" : user.username, "settled":false, "paired" : true}, $orderby : {_id : -1}})
                .then(function(doc){
                    // Add the potential_returns for our render object here
                    doc.forEach(function(x) {
                        // Calculate the potential returns
                        x.potential_returns = x.bet * x.odds
                    })
                    res.render('profile/bet-history', {bets: doc, user: req.user}); 
            });
        }else{
            res.redirect('/login');
        }
    });

potential_returns can be add to the <tr> in the same way as the other properties of doc

<tbody>
    {{#if bets}}
        {{#each bets}}
            <tr>
                <td>{{date this.createdAt}}</td>
                <td>{{this.market}}({{this.bet}})</td>
                <td>{{this.stake}}</td>
                <td>{{this.odds}}</td>
                <td>{{this.potential_returns}}</td>
            </tr>
        {{/each}}
    {{else}}
        <tr>
            <td>
                <p>You have no matched bets. Please come back later.</p>
            </td>
        </tr>
    {{/if}}        
</tbody>

Answer 2

Expanding on jervtub's answer, in order to use an external JS function, here's the final solution:

GET Request

var updates = require('./update.js');

app.get('/profile/bet-history', function(req, res, next){
        var user = req.user;
        if(user){
            Bet.find({$query : {"username" : user.username, "settled":false, "paired" : true}, $orderby : {_id : -1}})
                .then(function(doc){
                    // Add the potential_returns for our render object here
                    doc.forEach(function(x) {
                        updates.calcReturns(x);
                    })
                    res.render('profile/bet-history', {bets: doc, user: req.user}); 
            });
        }else{
            res.redirect('/login');
        }
});

Update.js File

module.exports = {
    calcReturns : function(x){
        if(x.bet == "Back"){
            x.potential_returns = x.stake * x.odds + x.stake;
        }else{
            x.potential_returns = x.stake * 2;
        }
    }
};

Handlebars Template

<tbody>
    {{#if bets}}
        {{#each bets}}
            <tr>
                <td>{{date this.createdAt}}</td>
                <td>{{this.market}}({{this.bet}})</td>
                <td>{{this.stake}}</td>
                <td>{{this.odds}}</td>
                <td>{{this.potential_returns}}</td>
            </tr>
        {{/each}}
    {{else}}
        <tr>
            <td>
                <p>You have no matched bets. Please come back later.</p>
            </td>
        </tr>
    {{/if}}        
</tbody>