add context to Parse.Object.save

[mtrezza]

Exposes the context object in Parse.Object.save() so that parameters can be made accessible in Cloud Code triggers beforeSave, afterSave.

Example:

const obj = new TestObject();
await obj.save(null, {context: {a: "a"}});

Parse.Cloud.beforeSave("TestObject", req => {
    console.log(req.context.a);
});

Parse.Cloud.afterSave("TestObject", req => {
    console.log(req.context.a);
});  

---

Don't merge until

• Concept agreed on in Make trigger context accessible in save parse-server#6459
• JS doc added in code for ‘context’

[codecov]

Codecov Report

Merging #1150 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #1150   +/-   ##
=======================================
  Coverage   92.30%   92.31%           
=======================================
  Files          54       54           
  Lines        5235     5241    +6     
  Branches     1169     1171    +2     
=======================================
+ Hits         4832     4838    +6     
  Misses        403      403           

Impacted Files	Coverage Δ
src/ParseObject.js	89.61% <100.00%> (+0.02%)	⬆️
src/RESTController.js	84.90% <100.00%> (+0.38%)	⬆️

---

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[mtrezza]

The context is transmitted as _context property in REST request body as part of the object properties.

I did not find an existing similar use of internal properties in the REST request, but according to the docs a field name must start with a letter, so there cannot be a conflict with an object property:

Key names must contain only numbers, letters, and underscore, and must start with a letter.

So using _context as internal property in a REST request seems OK, it is also used for internal field names such as _created_at in the DB.

[dplewis]

Quick comment

[dplewis]

Thanks! I will try to do a release soon

[mtrezza]

Thanks! Would be great if you could make a release with parse server release that will merge parse-community/parse-server#6626.