This Express Middleware will allow you to send a subset of a JSON object
instead of the entire object from your HTTP services. To do so, your services
will begin accepting the ?fields= query-string that, using a simple language,
will specify which fields and sub-fields to keep and which to ignore.
If you've used the Google APIs, provided a ?fields= query-string to get a
Partial Response,
and wanted to do the same for your own server, now you can do so with this
middleware.
Underneath, this middleware uses json-mask. Use it directly without this middleware if you need more flexibility.
npm install express-partial-response
const express = require('express');
const partialResponse = require('express-partial-response');
const app = express();
app.use(partialResponse());
app.get('/', (req, res) => {
res.json({
firstName: 'Mohandas',
lastName: 'Gandhi',
aliases: [
{
firstName: 'Mahatma',
lastName: 'Gandhi'
},
{
firstName: 'Bapu'
}
]
});
});
app.listen(4000);Let's test it:
$ curl 'http://localhost:4000'
{"firstName":"Mohandas","lastName":"Gandhi","aliases":[{"firstName":"Mahatma","lastName":"Gandhi"},{"firstName":"Bapu"}]}
$ # Let's just get the first name
$ curl 'http://localhost:4000?fields=lastName'
{"lastName":"Gandhi"}
$ # Now, let's just get the first names directly as well as from aliases
$ curl 'http://localhost:4000?fields=firstName,aliases(firstName)'
{"firstName":"Mohandas","aliases":[{"firstName":"Mahatma"},{"firstName":"Bapu"}]}
Note: take a look at /example.
Look at json-mask for the available syntax of the fields param.
query specifies the query-string to use. Defaults to fields
app.use(
partialResponse({
query: 'filter'
})
);MIT. See LICENSE
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