:sparkles: created method to join a group from frontend

backend/lib/routes/membership/join.js

 const validators = {
     payload: Joi.object({
         profile_id: Joi.number().required(),
-        target_id: Joi.number().allow(null),
+        target_id: Joi.number().required(),
         grouping_id: Joi.number().allow(null),
         grouping_name: Joi.string().allow(null),
         grouping_type: Joi.string().allow(null),
         ...pluginConfig.docs,
         tags: ['api'],
         auth: false,
+        cors: true,
 
         /**
          * Join a grouping by creating a membership record

frontend/src/App.vue

 import {
     fetchProfilesByUserId,
     fetchMembershipsByProfileId,
+    postMembershipByProfileId
 } from '@/services'
 
 import helloWorld from '@/components/HelloWorld.vue'
 
         const t = async () => {
             const tempProfiles = await fetchProfilesByUserId(1)
-            const groupings = []
+            let groupings = []
+            for(let p of tempProfiles) {
+                const memberships = await fetchMembershipsByProfileId(p.profile_id)
+                groupings.push(memberships)
+            }
+            console.log(groupings)
+            groupings = []
+            await postMembershipByProfileId({ profileId: 1, targetId: 20 })
             for(let p of tempProfiles) {
                 const memberships = await fetchMembershipsByProfileId(p.profile_id)
                 groupings.push(memberships)

frontend/src/entities/grouping/grouping.schema.js

         grouping_type: Joi.string()
     }),
     /** fields required before saving */
-    required: [ 'grouping_id', 'grouping_name', 'grouping_type' ],
+    required: [ 'grouping_id' ],
     validate(instance) {
         return this.properties.validate(instance)
     }

frontend/src/services/grouping.service.js

     return validGroupingInstances
 }
 
-export { fetchMembershipsByProfileId }
+const postMembershipByProfileId = async ({ profileId, targetId, groupingType = 'match' }) => {
+    const membership = {
+        profile_id: profileId,
+        target_id: targetId,
+        grouping_type: groupingType,
+        grouping_name: `delete_${profileId}_${targetId}`
+    }
+    const createdMembershipRecord = await db.post(`/membership/join`, membership)
+    console.log(createdMembershipRecord)
+    return createdMembershipRecord
+}
+export { fetchMembershipsByProfileId, postMembershipByProfileId }

frontend/src/utils/db.js

         this.apiPrefix = prefix
     }
     async get(endpoint) {
-        const header = headerTemplate
+        const header = { headerTemplate }
         header.method = 'GET'
         try {
             console.log(`${remote}${endpoint}`)
             console.error(error)
         }
     }
+    async post(endpoint, payload = {}) {
+        const header = { ...headerTemplate }
+        header.method = 'POST'
+        header.body = JSON.stringify(payload)
+        try {
+            let res = await fetch(`${remote}${endpoint}`, header)
+            if (!res.ok) {
+                throw Error(res.statusText)
+            }
+            const jsonRes = await res.json()
+            return jsonRes.data
+        } catch (error) {
+            console.error(error)
+        }
+    }
     async put(endpoint, entry) {
         /** from ajv schema validation */
         if (entry.isValid()) {