How to create a foreign key using curl command

Parse Server 📡
#1

Hi, I am using Postgres in the back-end and I want to create a table, so I created a schema first by using the following command:

curl -X POST \
  -H "X-Parse-Application-Id: xxxxxx" \
  -H "X-Parse-Master-Key: xxxxxx" \
  -H "Content-Type: application/json" \
  -d '
    {
      "className": "PaymentHistory",
      "fields": {
        "paymentMethod": {
          "type": "String"
        },
        "paymentTime": {
          "type": "Date"
        },
        "paymentAmount": {
          "type": "Number"
        },
        "paymentStatus": {
          "type": "Boolean"
        }
      }
    }' \
  http://127.0.0.1:1337/parse/schemas/PaymentHistory

Parse server already has a _User table with objectid and username. objectid is the primary key in the _User table. I want to link my PaymentHistory table by using the objectid in the _User table as the foreign key in my PaymentHistory table. How do I change my curl command to create the foreign key?
I know there is a relations section in the document: REST API Guide | Parse
But the document is not very clear and I still don’t know how to use it.

I understand parse server works better with MongoDB, but I cannot install MongoDB in my system. So, I have to use Postgres. I just hope there is a way to create a foreign key relation via curl. Thanks

#2

I believe you should create a pointer for User class.

curl -X POST \
  -H "X-Parse-Application-Id: xxxxxx" \
  -H "X-Parse-Master-Key: xxxxxx" \
  -H "Content-Type: application/json" \
  -d '
    {
      "className": "PaymentHistory",
      "fields": {
        "paymentUser": {"type": "Pointer", "required": false, "targetClass": "_User"}
      }
    }' \
  http://127.0.0.1:1337/parse/schemas/PaymentHistory
#3

@uzaysan Thank you very much! Could I ask some follow-up questions? Is there a way to impose a “unique” requirement for a particular column? For example, if I have a phone_number column, I want every number in the phone_number column be a unique number. Is there way to specify this? Moreover, is there a way to specify string length in the “String” type? Thanks

#4

For unique property, you can create a unique index for phone_number column. I create my indexes on database directly. So I dont know ıf you can define a unique index from parse schema but you can try this.

{
      "className": "ClassName",
      "fields": {
        "phone_number": {"type": "String"}
      },
      "indexes": {
        "phone_number_index_name": {
          "phone_number": 1,
          "unique": true,
        }
      }
    }

I’m not sure if unique: true will work. If it doesnt work, You can download mongo compass. And create indexes visually.

I dont think this is possible. But you can define a beforeSave trigger for that.

Parse.Cloud.beforeSave("ClassName", request => {
  const object = {request};
  if (object.get('phone_number').length > 10) {
    throw new Error('phone_number field must be 10 digits');
  }
});
#5

@uzaysan Thank you very much. I will give it a try.

#6

@uzaysan I used the pointer method to generate a new table with a foreign key. Here is the command I used:

curl -X POST \
  -H "X-Parse-Application-Id: xxxx" \
  -H "X-Parse-Master-Key: xxxx" \
  -H "Content-Type: application/json" \
  -d '
    {
      "className": "PaymentHistory",
      "fields": {
      "payer": {"type": "Pointer", 
       "required": false, 
       "targetClass": "_User"},
        "paymentMethod": {
          "type": "String"
        },
        "paymentTime": {
          "type": "Date"
        },
        "paymentAmount": {
          "type": "Number"
        },
        "paymentStatus": {
          "type": "Boolean"
        }
      }
    }' \
  http://127.0.0.1:1337/parse/schemas/PaymentHistory

However, it looks like the “payer” column does not have any indication that it is a foreign key (see the screenshot). Is this correct? How do I check whether the PaymentHistory table is working using the curl command?

If I want to use curl post to test this table, the “payer” value should be objectid in the _User table, right? Also, how do I generate “Date” value using the curl command to populate the paymentTime column?

Thanks

image

#7

Thats normal. Pointers are stored in text format on database with Classname$ObjectId format. If you set a user pointer for that field, It will look like _User$Yght75scF5 where Yght75scF5 is objectId of the user.

fields: {paymentTime : {type: "Date", required: false}}
This should work.

#8

@uzaysan Thanks. This works. But my question is: could I use “curl -X POST” to add a row in this table? For example, in swift, I can add one row by using

 let user = try? User.current?toPointer()
  let payment = PaymentHistory(payer: user, paymentMethod: "credit card", paymentTime: Date(), paymentAmount: 100, paymentStatus: true)
  payment.save {}

Is there an equivalent curl -X POST command? Thanks

#9

@uzaysan also, parse automatically added “_rperm” column and “_wperm” column to the table. What do those two columns do?

#10 
curl -X POST \
  -H "X-Parse-Application-Id: xxxxxx" \
  -H "X-Parse-Master-Key: xxxxxx" \
  -H "Content-Type: application/json" \
  -d '{"paymentTime":{"__type":"Date","iso":"2021-10-07T17:03:00.000Z"}}' \
  http://127.0.0.1:1337/parse/classes/PaymentHistory

iso is iso string of the date.

_rperm is read permissions. _wperm is write permissions. They are there for ACLs.

#11

@uzaysan Thanks. Is there an equivalent way to add payer: user pointer using “curl -X POST”? I am just curious:) Also, some people said I should not add columns to _User table. Is this true? If I am not allowed the add columns to the _User table, how could I add a profile image for a user? Create a new table and reference to the _User table?

#12

Here is an example with Date and user pointer

curl -X POST \
  -H "X-Parse-Application-Id: xxxxxx" \
  -H "Content-Type: application/json" \
  -d '{
    "payer": {
      "__type": "Pointer",
      "className": "_User",
      "objectId": "UserObjectId"
    },
    "paymentTime": {
      "__type":"Date",
      "iso":"2021-10-07T17:03:00.000Z"
    }
  }' \
  http://127.0.0.1:1337/parse/classes/PaymentHistory

Thats not true. You can add columns to User table.

#13

@uzaysan Thank you very much! It works. The only small difference is you use “__type”: “Pointer” and I used “type”: “Pointer”. It seems “type” works, but I did not try “__type”. So, I don’t know whether " “__type” will work.

Also, is there a bytea data type for me to save image data?

I think your answers should be part of the official document.

#14

They are already included in the docs.

curl -X POST \
  -H "X-Parse-Application-Id: ${APPLICATION_ID}" \
  -H "X-Parse-REST-API-Key: ${REST_API_KEY}" \
  -H "Content-Type: image/jpeg" \
  --data-binary '@myPicture.jpg' \
  https://YOUR.PARSE-SERVER.HERE/parse/files/pic.jpg

This is also taken from docs:

#15

@uzaysan Thanks for your answers. But where does parse server save the image files after I upload them? Does parse save them in a particular folder? Do I need to configure file storage service, like AWS S3?

#16

İf you don’t set an adapter, files are saved to database. But you can set an adapter if you want to use aws s3, azure or Google.

#17

@uzaysan Are you sure the uploaded file is saved in the database? According to the document you sent to me. After a user uploaded a file successfully, the response is:
image

It seems that the response includes a url pointing to the file. So, I am wondering whether the file is indeed in the database.

#18

I’m sure. İf you don’t specify a file adapter, file is saved to database. That url you see is parse server public url you defined in parse server constructor. When you don’t have a file adapter, parse proxies the file

#19

@uzaysan Understand now. Thanks

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