问题
I am using a PUT request in my Rails application. Now, a new HTTP verb, PATCH has been implemented by browsers. So, I want to know what the main difference between PATCH and PUT requests are, and when we should use one or the other.
回答1:
HTTP verbs are probably one of the most cryptic things about the HTTP protocol. They exist, and there are many of them, but why do they exist?
Rails seems to want to support many verbs and add some verbs that aren't supported by web browsers natively.
Here's an exhaustive list of http verbs: http://annevankesteren.nl/2007/10/http-methods
There the HTTP patch from the official RFC: https://datatracker.ietf.org/doc/rfc5789/?include_text=1
The PATCH method requests that a set of changes described in the request entity be applied to the resource identified by the Request- URI. The set of changes is represented in a format called a "patch document" identified by a media type. If the Request-URI does not point to an existing resource, the server MAY create a new resource, depending on the patch document type (whether it can logically modify a null resource) and permissions, etc.
The difference between the PUT and PATCH requests is reflected in the way the server processes the enclosed entity to modify the resource identified by the Request-URI. In a PUT request, the enclosed entity is considered to be a modified version of the resource stored on the origin server, and the client is requesting that the stored version be replaced. With PATCH, however, the enclosed entity contains a set of instructions describing how a resource currently residing on the origin server should be modified to produce a new version. The PATCH method affects the resource identified by the Request-URI, and it also MAY have side effects on other resources; i.e., new resources may be created, or existing ones modified, by the application of a PATCH.
As far as I know, the PATCH verb is not used as it is in rails applications... As I understand this, the RFC patch verb should be used to send patch instructions like when you do a diff between two files. Instead of sending the whole entity again, you send a patch that could be much smaller than resending the whole entity.
Imagine you want to edit a huge file. You edit 3 lines. Instead of sending the file back, you just have to send the diff. On the plus side, sending a patch request could be used to merge files asynchronously. A version control system could potentially use the PATCH verb to update code remotely.
One other possible use case is somewhat related to NoSQL databases, it is possible to store documents. Let say we use a JSON structure to send back and forth data from the server to the client. If we wanted to delete a field, we could use a syntax similar to the one in mongodb for $unset. Actually, the method used in mongodb to update documents could be probably used to handle json patches.
Taking this example:
db.products.update(
{ sku: "unknown" },
{ $unset: { quantity: "", instock: "" } }
)
We could have something like this:
PATCH /products?sku=unknown
{ "$unset": { "quantity": "", "instock": "" } }
Last, but not least, people can say whatever they want about HTTP verbs. There is only one truth, and the truth is in the RFCs.
回答2:
I spent couple of hours with google and found the answer here
PUT => If user can update all or just a portion of the record, use PUT (user controls what gets updated)
PUT /users/123/email
new.email@example.org
PATCH => If user can only update a partial record, say just an email address (application controls what can be updated), use PATCH.
PATCH /users/123
[description of changes]
Why Patch
PUT method need more bandwidth or handle full resources instead on partial. So PATCH was introduced to reduce the bandwidth.
Explanation about PATCH
PATCH is a method that is not safe, nor idempotent, and allows full and partial updates and side-effects on other resources.
PATCH is a method which enclosed entity contains a set of instructions describing how a resource currently residing on the origin server should be modified to produce a new version.
PATCH /users/123
[
{ "op": "replace", "path": "/email", "value": "new.email@example.org" }
]
Here more information about put and patch
回答3:
put
if i want to change myfirst name then send put request for Update
{ "first": "Nazmul", "last": "hasan" }
but here has one problem is put request that when i want to send put request i have to send all two parameters that is first and last
so it is mandatory to send all value again
patch :patch request says . only send the data which one you want to update and it won't effecting or changing other data .
so no need to send all value again . just i want to update my first name so i need to send only first name to update .
回答4:
Here are the difference between POST, PUT and PATCH methods of a HTTP protocol.
POST
A HTTP.POST method always creates a new resource on the server. Its a non-idempotent request i.e. if user hits same requests 2 times it would create another new resource if there is no constraint.
http post method is like a INSERT query in SQL which always creates a new record in database.
Example: Use POST method to save new user, order etc where backend server decides the resource id for new resource.
PUT
In HTTP.PUT method the resource is first identified from the URL and if it exists then it is updated otherwise a new resource is created. When the target resource exists it overwrites that resource with a complete new body. That is HTTP.PUT method is used to CREATE or UPDATE a resource.
http put method is like a MERGE query in SQL which inserts or updates a record depending upon whether the given record exists.
PUT request is idempotent i.e. hitting the same requests twice would update the existing recording (No new record created). In PUT method the resource id is decided by the client and provided in the request url.
Example: Use PUT method to update existing user or order.
PATCH
A HTTP.PATCH method is used for partial modifications to a resource i.e. delta updates.
http patch method is like a UPDATE query in SQL which sets or updates selected columns only and not the whole row.
Example: You could use PATCH method to update order status.
PATCH /api/users/40450236/order/10234557
Request Body: {status: 'Delivered'}
回答5:
There are limitations in PUT over PATCH while making updates. Using PUT requires us to specify all attributes even if we want to change only one attribute. But if we use the PATCH method we can update only the fields we need and there is no need to mention all the fields. PATCH does not allow us to modify a value in an array, or remove an attribute or array entry.
回答6:
PUT and PATCH methods are similar in nature, but there is a key difference.
PUT - in PUT request, the enclosed entity would be considered as the modified version of a resource which residing on server and it would be replaced by this modified entity.
PATCH - in PATCH request, enclosed entity contains the set of instructions that how the entity which residing on server, would be modified to produce a newer version.
回答7:
Put and Patch method are similar . But in rails it has different metod If we want to update/replace whole record then we have to use Put method. If we want to update particular record use Patch method.
回答8:
According to HTTP terms, The PUT request is just-like a database update statement.
PUT - is used for modifying existing resource (Previously POSTED). On the other hand the PATCH request is used to update some portion of existing resource.
For Example:
Customer Details:
// This is just a example.
firstName = "James";
lastName = "Anderson";
email = "email@domain.com";
phoneNumber = "+92 1234567890";
//..
When we want to update to entire record ? we have to use Http PUT verb for that.
such as:
// Customer Details Updated.
firstName = "James++++";
lastName = "Anderson++++";
email = "email@Updated.com";
phoneNumber = "+92 0987654321";
//..
On the other hand if we want to update only the portion of the record not the entire record then go for Http PATCH verb.
such as:
// Only Customer firstName and lastName is Updated.
firstName = "Updated FirstName";
lastName = "Updated LastName";
//..
PUT VS POST:
When using PUT request we have to send all parameter such as firstName, lastName, email, phoneNumber Where as In patch request only send the parameters which one we want to update and it won't effecting or changing other data.
For more details please visit : https://fullstack-developer.academy/restful-api-design-post-vs-put-vs-patch/
来源：https://stackoverflow.com/questions/21660791/what-is-the-main-difference-between-patch-and-put-request