Filtering and pagination

Author: Bojan Tomic

src/main/java/com/howtographql/hackernews/LinkFilter.java

@@ -0,0 +1,30 @@
+package com.howtographql.hackernews;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+
+/**
+ * Created by bojan.tomic on 7/9/17.
+ */
+public class LinkFilter {
+
+    private String descriptionContains;
+    private String urlContains;
+
+    @JsonProperty("description_contains")
+    public String getDescriptionContains() {
+        return descriptionContains;
+    }
+
+    public void setDescriptionContains(String descriptionContains) {
+        this.descriptionContains = descriptionContains;
+    }
+
+    @JsonProperty("url_contains")
+    public String getUrlContains() {
+        return urlContains;
+    }
+
+    public void setUrlContains(String urlContains) {
+        this.urlContains = urlContains;
+    }
+}

src/main/java/com/howtographql/hackernews/LinkRepository.java

@@ -1,15 +1,19 @@
 package com.howtographql.hackernews;
 
+import com.mongodb.client.FindIterable;
 import com.mongodb.client.MongoCollection;
-import com.mongodb.client.model.Filters;
 
 import org.bson.Document;
+import org.bson.conversions.Bson;
 import org.bson.types.ObjectId;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Optional;
 
+import static com.mongodb.client.model.Filters.and;
 import static com.mongodb.client.model.Filters.eq;
+import static com.mongodb.client.model.Filters.regex;
 
 /**
  * Created by bojan.tomic on 7/2/17.
@@ -18,7 +22,7 @@ public class LinkRepository {
 
     private final MongoCollection<Document> links;
 
-    public LinkRepository(MongoCollection<Document> links) {
+    LinkRepository(MongoCollection<Document> links) {
         this.links = links;
     }
 
@@ -27,11 +31,12 @@ public Link findById(String id) {
         return link(doc);
     }
 
-    public List<Link> getAllLinks() {
-        links.deleteOne(Filters.eq("_id", new ObjectId("59592cd33b067a54782a64d5")));
-        links.deleteOne(Filters.eq("_id", new ObjectId("595932443b067a54782a64d6")));
+    public List<Link> getAllLinks(LinkFilter filter, int skip, int first) {
+        Optional<Bson> mongoFilter = Optional.ofNullable(filter).map(this::buildFilter);
+        
         List<Link> allLinks = new ArrayList<>();
-        for (Document doc : links.find()) {
+        FindIterable<Document> documents = mongoFilter.map(links::find).orElseGet(links::find);
+        for (Document doc : documents.skip(skip).limit(first)) {
             allLinks.add(link(doc));
         }
         return allLinks;
@@ -44,6 +49,23 @@ public void saveLink(Link link) {
         doc.append("postedBy", link.getUserId());
         links.insertOne(doc);
     }
+
+    private Bson buildFilter(LinkFilter filter) {
+        String descriptionPattern = filter.getDescriptionContains();
+        String urlPattern = filter.getUrlContains();
+        Bson descriptionCondition = null;
+        Bson urlCondition = null;
+        if (descriptionPattern != null && !descriptionPattern.isEmpty()) {
+            descriptionCondition = regex("description", ".*" + descriptionPattern + ".*", "i");
+        }
+        if (urlPattern != null && !urlPattern.isEmpty()) {
+            urlCondition = regex("url", ".*" + urlPattern + ".*", "i");
+        }
+        if (descriptionCondition != null && urlCondition != null) {
+            return and(descriptionCondition, urlCondition);
+        }
+        return descriptionCondition != null ? descriptionCondition : urlCondition;
+    }
 
     private Link link(Document doc) {
         return new Link(

src/main/java/com/howtographql/hackernews/Query.java

@@ -15,7 +15,7 @@ public Query(LinkRepository linkRepository) {
         this.linkRepository = linkRepository;
     }
 
-    public List<Link> allLinks() {
-        return linkRepository.getAllLinks();
+    public List<Link> allLinks(LinkFilter filter, Number skip, Number first) {
+        return linkRepository.getAllLinks(filter, skip.intValue(), first.intValue());
     }
 }

src/main/resources/schema.graphqls

@@ -1,8 +1,24 @@
+schema {
+    query: Query
+    mutation: Mutation
+}
+
+type Query {
+    allLinks(filter: LinkFilter, skip: Int = 0, first: Int = 0): [Link]
+}
+
+type Mutation {
+    createLink(url: String!, description: String!): Link
+    createUser(name: String!, authProvider: AuthData!): User
+    signinUser(auth: AuthData): SigninPayload
+    createVote(linkId: ID, userId: ID): Vote
+}
+
 type Link {
     id: ID!
     url: String!
     description: String
-    postedBy: User!
+    postedBy: User
 }
 
 type User {
@@ -12,11 +28,6 @@ type User {
     password: String
 }
 
-input AuthData {
-    email: String!
-    password: String!
-}
-
 type SigninPayload {
     token: String
     user: User
@@ -29,20 +40,14 @@ type Vote {
     link: Link!
 }
 
-scalar DateTime
-
-type Query {
-    allLinks: [Link]
+input AuthData {
+    email: String!
+    password: String!
 }
 
-type Mutation {
-    createLink(url: String!, description: String!): Link
-    createUser(name: String!, authProvider: AuthData!): User
-    signinUser(auth: AuthData): SigninPayload!
-    createVote(linkId: ID, userId: ID): Vote
+input LinkFilter {
+    description_contains: String
+    url_contains: String
 }
 
-schema {
-    query: Query
-    mutation: Mutation
-}
+scalar DateTime