add import view

springboot/.gitignore

@@ -30,3 +30,4 @@ kontorHSQLDB*
 src/main/resources/application-local.properties
 src/main/resources/application-prod.properties
 src/main/resources/application-*.yml
+/uploaded-files/

springboot/build.gradle

@@ -62,7 +62,10 @@ dependencies {
     implementation 'com.h2database:h2'
     implementation libs.hsqldb
     runtimeOnly 'org.mariadb.jdbc:mariadb-java-client'
-    implementation 'com.sun.mail:javax.mail:1.6.2'
+    implementation libs.mail
+    implementation libs.jackson
+    implementation libs.gson
+    implementation libs.json
     implementation 'org.hibernate.orm:hibernate-community-dialects'
     testImplementation('org.springframework.boot:spring-boot-starter-test') {
         exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'

springboot/gradle/libs.versions.toml

@@ -20,6 +20,10 @@ springboot = "3.2.5"
 springdependencies = "1.1.4"
 vaadin = "24.3.8"
 lombok = "8.6"
+gson = "2.9.0"
+jackson = "2.16.1"
+json_simple = "1.1.1"
+mail = "1.6.2"
 
 [libraries]
 args4j = { module = "args4j:args4j", version.ref = "args4j" }
@@ -31,6 +35,10 @@ mockito = { module = "org.mockito:mockito-all", version.ref = "mockito" }
 picocli = { module = "info.picocli:picocli", version.ref = "picoli" }
 slf4j = { module = "org.slf4j:slf4j-api", version.ref = "slf4j" }
 hsqldb = { module = "org.hsqldb:hsqldb", version.ref = "hsqldb" }
+gson = { module = "com.google.code.gson:gson", version.ref = "gson" }
+jackson = { module = "com.fasterxml.jackson.core:jackson-databind", version.ref = "jackson" }
+json = { module = "com.googlecode.json-simple:json-simple", version.ref ="json_simple" }
+mail = { module = "com.sun.mail:javax.mail", version.ref  ="mail" }
 sqlite-jdbc = { module = "org.xerial:sqlite-jdbc", version.ref = "sqlite" }
 vaadin-bom = { module = "com.vaadin:vaadin-bom", version.ref = "vaadin" }
 asciidoctorGradleJvmGems = { module = "org.asciidoctor:asciidoctor-gradle-jvm-gems", version.ref= "asciidoctor" }

springboot/src/main/java/de/thpeetz/kontor/admin/SetupModuleAdmin.java

@@ -1,7 +1,9 @@
 package de.thpeetz.kontor.admin;
 
-import com.vaadin.flow.component.page.Meta;
 import de.thpeetz.kontor.admin.data.*;
+import de.thpeetz.kontor.admin.repository.AuthorizationMatrixRepository;
+import de.thpeetz.kontor.admin.repository.MailAccountRepository;
+import de.thpeetz.kontor.admin.repository.UserRepository;
 import de.thpeetz.kontor.admin.services.AdminService;
 import de.thpeetz.kontor.admin.services.MetaDataService;
 import de.thpeetz.kontor.mailclient.data.MailAccount;

springboot/src/main/java/de/thpeetz/kontor/admin/data/MetaDataTable.java

@@ -5,10 +5,15 @@ import jakarta.persistence.*;
 import jakarta.validation.constraints.NotNull;
 import lombok.Getter;
 import lombok.Setter;
+import lombok.extern.slf4j.Slf4j;
 
+import java.text.ParseException;
+import java.text.SimpleDateFormat;
+import java.util.Date;
 import java.util.LinkedList;
 import java.util.List;
 
+@Slf4j
 @Entity
 @Getter
 @Setter
@@ -23,4 +28,11 @@ public class MetaDataTable extends AbstractEntity {
 
     @OneToMany(fetch = FetchType.EAGER, mappedBy = "table")
     private List<MetaDataColumn> tableColumns = new LinkedList<>();
+
+    public void updateTableName(String value) {
+        if (!this.getTableName().equals(value)) {
+            this.setTableName(value);
+            log.info("update tableName");
+        }
+    }
 }

springboot/src/main/java/de/thpeetz/kontor/admin/repository/AuthorizationMatrixRepository.java

@@ -1,8 +1,10 @@
-package de.thpeetz.kontor.admin.data;
+package de.thpeetz.kontor.admin.repository;
 
 import java.util.List;
-import java.util.UUID;
 
+import de.thpeetz.kontor.admin.data.AuthorizationMatrix;
+import de.thpeetz.kontor.admin.data.Role;
+import de.thpeetz.kontor.admin.data.User;
 import org.springframework.data.jpa.repository.JpaRepository;
 
 public interface AuthorizationMatrixRepository extends JpaRepository<AuthorizationMatrix, String> {

springboot/src/main/java/de/thpeetz/kontor/admin/repository/MailAccountRepository.java

@@ -1,4 +1,4 @@
-package de.thpeetz.kontor.admin.data;
+package de.thpeetz.kontor.admin.repository;
 
 import de.thpeetz.kontor.mailclient.data.MailAccount;
 import org.springframework.data.jpa.repository.JpaRepository;

springboot/src/main/java/de/thpeetz/kontor/admin/repository/MetaDataColumnRepository.java

@@ -1,5 +1,7 @@
-package de.thpeetz.kontor.admin.data;
+package de.thpeetz.kontor.admin.repository;
 
+import de.thpeetz.kontor.admin.data.MetaDataColumn;
+import de.thpeetz.kontor.admin.data.MetaDataTable;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;

springboot/src/main/java/de/thpeetz/kontor/admin/repository/MetaDataTableRepository.java

@@ -1,5 +1,6 @@
-package de.thpeetz.kontor.admin.data;
+package de.thpeetz.kontor.admin.repository;
 
+import de.thpeetz.kontor.admin.data.MetaDataTable;
 import org.springframework.data.jpa.repository.JpaRepository;
 
 public interface MetaDataTableRepository extends JpaRepository<MetaDataTable, String> {

springboot/src/main/java/de/thpeetz/kontor/admin/repository/ModuleDataRepository.java

@@ -1,5 +1,6 @@
-package de.thpeetz.kontor.admin.data;
+package de.thpeetz.kontor.admin.repository;
 
+import de.thpeetz.kontor.admin.data.ModuleData;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;

springboot/src/main/java/de/thpeetz/kontor/admin/repository/RoleRepository.java

@@ -1,7 +1,8 @@
-package de.thpeetz.kontor.admin.data;
+package de.thpeetz.kontor.admin.repository;
 
 import java.util.List;
 
+import de.thpeetz.kontor.admin.data.Role;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;

springboot/src/main/java/de/thpeetz/kontor/admin/repository/UserRepository.java

@@ -1,7 +1,8 @@
-package de.thpeetz.kontor.admin.data;
+package de.thpeetz.kontor.admin.repository;
 
 import java.util.List;
 
+import de.thpeetz.kontor.admin.data.User;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;

springboot/src/main/java/de/thpeetz/kontor/admin/services/AdminService.java

@@ -6,11 +6,11 @@ import java.util.List;
 import org.springframework.stereotype.Service;
 
 import de.thpeetz.kontor.admin.data.AuthorizationMatrix;
-import de.thpeetz.kontor.admin.data.AuthorizationMatrixRepository;
+import de.thpeetz.kontor.admin.repository.AuthorizationMatrixRepository;
 import de.thpeetz.kontor.admin.data.Role;
-import de.thpeetz.kontor.admin.data.RoleRepository;
+import de.thpeetz.kontor.admin.repository.RoleRepository;
 import de.thpeetz.kontor.admin.data.User;
-import de.thpeetz.kontor.admin.data.UserRepository;
+import de.thpeetz.kontor.admin.repository.UserRepository;
 import lombok.extern.slf4j.Slf4j;
 
 @Slf4j

springboot/src/main/java/de/thpeetz/kontor/admin/services/KontorUserDetailsService.java

@@ -1,6 +1,9 @@
 package de.thpeetz.kontor.admin.services;
 
 import de.thpeetz.kontor.admin.data.*;
+import de.thpeetz.kontor.admin.repository.AuthorizationMatrixRepository;
+import de.thpeetz.kontor.admin.repository.RoleRepository;
+import de.thpeetz.kontor.admin.repository.UserRepository;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.security.core.GrantedAuthority;

springboot/src/main/java/de/thpeetz/kontor/admin/services/MailService.java

@@ -1,7 +1,7 @@
 package de.thpeetz.kontor.admin.services;
 
 import de.thpeetz.kontor.mailclient.data.MailAccount;
-import de.thpeetz.kontor.admin.data.MailAccountRepository;
+import de.thpeetz.kontor.admin.repository.MailAccountRepository;
 import lombok.extern.slf4j.Slf4j;
 
 import java.util.List;

springboot/src/main/java/de/thpeetz/kontor/admin/services/MetaDataService.java

@@ -3,12 +3,16 @@ package de.thpeetz.kontor.admin.services;
 import org.springframework.stereotype.Service;
 
 import de.thpeetz.kontor.admin.data.MetaDataColumn;
-import de.thpeetz.kontor.admin.data.MetaDataColumnRepository;
+import de.thpeetz.kontor.admin.repository.MetaDataColumnRepository;
 import de.thpeetz.kontor.admin.data.MetaDataTable;
-import de.thpeetz.kontor.admin.data.MetaDataTableRepository;
+import de.thpeetz.kontor.admin.repository.MetaDataTableRepository;
 import lombok.extern.slf4j.Slf4j;
 
+import java.sql.Date;
 import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.atomic.AtomicReference;
 
 @Slf4j
 @Service
@@ -23,6 +27,10 @@ public class MetaDataService {
         this.metaDataColumnRepository = metaDataColumnRepository;
     }
 
+    public List<MetaDataTable> findAllTables() {
+        return metaDataTableRepository.findAll();
+    }
+
     public MetaDataTable getTable(String tableName) {
         MetaDataTable table = metaDataTableRepository.findByTableName(tableName);
         if (table == null) {
@@ -34,6 +42,14 @@ public class MetaDataService {
         return table;
     }
 
+    private void deleteTable(MetaDataTable metaDataTable) {
+        List<MetaDataColumn> columns = metaDataTable.getTableColumns();
+        for (MetaDataColumn column: columns) {
+            metaDataColumnRepository.delete(column);
+        }
+        metaDataTableRepository.delete(metaDataTable);
+    }
+
     public void getColumn(MetaDataTable table, String columnName, String columnSyncName, String columnType, String columnModifier, Integer columnOrder, Boolean isShown, String columnLabel, Boolean showFilter, String filterLabel) {
         this.getColumn(table, columnName, columnSyncName, columnType, columnModifier, columnOrder, isShown, columnLabel, showFilter, filterLabel, null);
     }
@@ -123,7 +139,46 @@ public class MetaDataService {
         metaDataColumnRepository.save(metaDataColumn);
     }
 
-    public List<MetaDataTable> findAllTables() {
+    public String importData(Map<String, String> fields) {
-        return metaDataTableRepository.findAll();
+        AtomicReference<String> status = new AtomicReference<>("unknown");
+        String id = fields.get("id");
+        Optional<MetaDataTable> optional = metaDataTableRepository.findById(id);
+        if (optional.isEmpty()) {
+            log.info(" not found: {} with {}", id, fields);
+            status.set(id + "not found");
+            MetaDataTable checkExisting = metaDataTableRepository.findByTableName(fields.get("table_name"));
+            if (checkExisting != null) {
+                log.info("entry already there with different id ({}), will be deleted", checkExisting.getId());
+                deleteTable(checkExisting);
+            }
+            MetaDataTable metaDataTable = new MetaDataTable();
+            metaDataTable.setId(id);
+            metaDataTable.setTableName(fields.get("table_name"));
+            metaDataTableRepository.save(metaDataTable);
+        } else {
+            optional.ifPresent( entry -> {
+                log.info(" found: {}", entry.getTableName());
+                updateFields(entry, fields);
+                metaDataTableRepository.save(entry);
+                status.set("found");
+            });
+        }
+        return status.get();
+    }
+
+    private void updateFields(MetaDataTable metaDataTable, Map<String, String> fields) {
+        for (Map.Entry<String, String> entry : fields.entrySet()) {
+            String key = entry.getKey();
+            String value = entry.getValue();
+            switch (key) {
+                case "id", "created_date", "last_modified_date", "version":
+                    break;
+                case "table_name":
+                    metaDataTable.updateTableName(value);
+                    break;
+                default:
+                    log.info("field {} is unknown for table {}", key, MetaDataTable.class.getName());
+            }
+        }
     }
 }

springboot/src/main/java/de/thpeetz/kontor/admin/services/ModuleService.java

@@ -1,7 +1,7 @@
 package de.thpeetz.kontor.admin.services;
 
 import de.thpeetz.kontor.admin.data.ModuleData;
-import de.thpeetz.kontor.admin.data.ModuleDataRepository;
+import de.thpeetz.kontor.admin.repository.ModuleDataRepository;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.stereotype.Service;
 

springboot/src/main/java/de/thpeetz/kontor/common/data/AbstractEntity.java

@@ -31,4 +31,15 @@ public abstract class AbstractEntity {
 
     @LastModifiedDate
     private Date lastModifiedDate;
+
+    public void updateVersion(String value) {
+        if (value == null) {
+            log.info("value not given");
+            return;
+        }
+        if (version != Integer.valueOf(value).intValue()) {
+            log.info("update version");
+            version = Integer.valueOf(value).intValue();
+        }
+    }
 }

springboot/src/main/java/de/thpeetz/kontor/common/views/MainLayout.java

@@ -4,6 +4,7 @@ import com.vaadin.flow.component.applayout.AppLayout;
 import com.vaadin.flow.component.applayout.DrawerToggle;
 import com.vaadin.flow.component.html.H1;
 import com.vaadin.flow.component.html.H2;
+import com.vaadin.flow.component.icon.VaadinIcon;
 import com.vaadin.flow.component.orderedlayout.FlexComponent;
 import com.vaadin.flow.component.orderedlayout.HorizontalLayout;
 import com.vaadin.flow.component.orderedlayout.Scroller;
@@ -17,15 +18,14 @@ import de.thpeetz.kontor.admin.AdminConstants;
 import de.thpeetz.kontor.admin.services.AdminService;
 import de.thpeetz.kontor.bookshelf.BookshelfConstants;
 import de.thpeetz.kontor.comics.ComicConstants;
+import de.thpeetz.kontor.data.views.DataManagementView;
 import de.thpeetz.kontor.mailclient.views.EmailView;
 import de.thpeetz.kontor.media.MediaConstants;
 import de.thpeetz.kontor.security.SecurityService;
 import de.thpeetz.kontor.tysc.TyscConstants;
 import lombok.extern.slf4j.Slf4j;
-import org.springframework.security.core.GrantedAuthority;
 
 import java.util.ArrayList;
-import java.util.Collection;
 
 @Slf4j
 public class MainLayout extends AppLayout {
@@ -87,6 +87,7 @@ public class MainLayout extends AppLayout {
         sideNav.addItem(BookshelfConstants.getBookshelfNavigation());
         sideNav.addItem(MediaConstants.getMediaNavigation(roles));
         sideNav.addItem(new SideNavItem("Emails", EmailView.class));
+        sideNav.addItem(new SideNavItem("Data Management", DataManagementView.class, VaadinIcon.DATABASE.create()));
         securityService.getAuthenticatedUser().ifPresent(user -> {
             log.info("User {} found", user.getUsername());
             boolean isAdmin = user.getAuthorities().stream()

springboot/src/main/java/de/thpeetz/kontor/data/services/DataManagementService.java

@@ -0,0 +1,40 @@
+package de.thpeetz.kontor.data.services;
+
+import de.thpeetz.kontor.admin.data.MetaDataTable;
+import de.thpeetz.kontor.admin.repository.MetaDataTableRepository;
+import de.thpeetz.kontor.admin.services.MetaDataService;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.atomic.AtomicReference;
+
+@Slf4j
+@Service
+public class DataManagementService {
+
+    @Autowired
+    MetaDataTableRepository metaDataTableRepository;
+
+    @Autowired
+    MetaDataService metaDataService;
+
+    public DataManagementService() {
+
+    }
+
+    public String getEntry(String nodeName, Map<String, String> fields) {
+        AtomicReference<String> status = new AtomicReference<>("unknown");
+        switch (nodeName) {
+            case "meta_data_table":
+                //status.set(metaDataService.importData(fields));
+                break;
+            default:
+                log.debug("import for {} not implemented", nodeName);
+                break;
+        }
+        return status.get();
+    }
+}

springboot/src/main/java/de/thpeetz/kontor/data/views/DataManagementView.java

@@ -0,0 +1,49 @@
+package de.thpeetz.kontor.data.views;
+
+import com.vaadin.flow.component.checkbox.Checkbox;
+import com.vaadin.flow.component.orderedlayout.VerticalLayout;
+import com.vaadin.flow.router.PageTitle;
+import com.vaadin.flow.router.Route;
+import com.vaadin.flow.spring.annotation.SpringComponent;
+import de.thpeetz.kontor.common.views.MainLayout;
+import de.thpeetz.kontor.data.services.DataManagementService;
+import jakarta.annotation.security.PermitAll;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.context.annotation.Scope;
+
+import java.io.File;
+
+@Slf4j
+@SpringComponent
+@Scope("prototype")
+@PermitAll
+@Route(value = "common/import", layout = MainLayout.class)
+@PageTitle("Import Data | Kontor")
+public class DataManagementView extends VerticalLayout {
+
+    DataManagementService service;
+
+    public DataManagementView(DataManagementService service) {
+        this.service = service;
+        File uploadFolder = getUploadFolder();
+        UploadArea uploadArea = new UploadArea(uploadFolder);
+        Checkbox pruneTables = new Checkbox("Prune Table");
+        ImportArea importArea = new ImportArea(uploadFolder, pruneTables, service);
+
+        uploadArea.getUploadField().addSucceededListener(e -> {
+            uploadArea.hideErrorField();
+            importArea.processFiles();
+            uploadArea.getUploadField().clearFileList();
+        });
+
+        add(uploadArea, pruneTables, importArea);
+    }
+
+    private File getUploadFolder() {
+        File folder = new File("uploaded-files");
+        if (!folder.exists()) {
+            folder.mkdirs();
+        }
+        return folder;
+    }
+}

springboot/src/main/java/de/thpeetz/kontor/data/views/ImportArea.java

@@ -0,0 +1,111 @@
+package de.thpeetz.kontor.data.views;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import com.fasterxml.jackson.databind.node.JsonNodeType;
+import com.vaadin.flow.component.checkbox.Checkbox;
+import com.vaadin.flow.component.html.H4;
+import com.vaadin.flow.component.html.Paragraph;
+import com.vaadin.flow.component.orderedlayout.VerticalLayout;
+import de.thpeetz.kontor.data.services.DataManagementService;
+import lombok.extern.slf4j.Slf4j;
+import org.json.simple.parser.ParseException;
+
+import java.io.*;
+import java.util.*;
+
+@Slf4j
+public class ImportArea extends VerticalLayout {
+
+    protected File uploadFolder;
+    DataManagementService service;
+    boolean pruneTables = false;
+
+    public ImportArea(File uploadFolder, Checkbox pruneTablesCheckbox, DataManagementService service) {
+        this.uploadFolder = uploadFolder;
+        this.service = service;
+        this.pruneTables = pruneTablesCheckbox.isEnabled();
+        setMargin(true);
+    }
+
+    public void processFiles() {
+        removeAll();
+        if (pruneTables) {
+            add(new Paragraph("prune all tables"));
+        }
+        add(new H4("Process file"));
+
+        for (File file: uploadFolder.listFiles()) {
+            add(new Paragraph("reading " + file.getName()));
+            try {
+                processFile(file);
+            } catch (ParseException e) {
+                throw new RuntimeException(e);
+            } catch (FileNotFoundException e) {
+                throw new RuntimeException(e);
+            } catch (IOException e) {
+                throw new RuntimeException(e);
+            }
+        }
+    }
+
+    private void processFile(File file) throws FileNotFoundException, IOException, ParseException {
+        ObjectMapper objectMapper = new ObjectMapper();
+        JsonNode node = objectMapper.readTree(file);
+        log.info("parsing: {}, {}", node.getNodeType(), node.size());
+        Iterator<String> fieldNamesIterator = node.fieldNames();
+        while (fieldNamesIterator.hasNext()) {
+            String fieldName = fieldNamesIterator.next();
+            parseRoot(node, fieldName);
+        }
+    }
+
+    private void parseRoot(JsonNode parentNode, String field) {
+        JsonNode node = parentNode.get(field);
+        String nodeType = String.valueOf(node.getNodeType());
+        if (nodeType.equals("ARRAY")) {
+            log.info("  {}: {}", field, node.size());
+            Iterator<JsonNode> elements = node.elements();
+            while (elements.hasNext()) {
+                JsonNode subNode = elements.next();
+                String status = parseNode(subNode, field);
+                add(new Paragraph(status));
+            }
+        } else {
+            log.info("unknown type: {}", nodeType);
+        }
+    }
+
+    private String parseNode(JsonNode node, String nodeName) {
+        Map<String, String> fields = parseFields(node);
+        return service.getEntry(nodeName, fields);
+    }
+
+    private Map<String, String> parseFields(JsonNode node) {
+        Map<String, String> fields = new HashMap<>();
+        node.fieldNames().forEachRemaining(field -> {
+
+            JsonNode value = node.get(field);
+            log.debug("type: {}", value.getNodeType());
+            JsonNodeType nodeType = value.getNodeType();
+            switch (nodeType) {
+                case NUMBER:
+                    fields.put(field, String.valueOf(value.intValue()));
+                    break;
+                case STRING:
+                    String stringValue = value.textValue();
+                    if (stringValue.contains("\"")) {
+                        log.debug("remove double quotes");
+                        String stripped = stringValue.substring(1, stringValue.length()-1);
+                        fields.put(field, stripped);
+                    }
+                    fields.put(field, value.textValue());
+                    break;
+                default:
+                    log.debug("no implementation for type {}", nodeType.name());
+            }
+        });
+        log.debug("fields: {}", fields);
+        return fields;
+    }
+}

springboot/src/main/java/de/thpeetz/kontor/data/views/UploadArea.java

@@ -0,0 +1,58 @@
+package de.thpeetz.kontor.data.views;
+
+import com.vaadin.flow.component.html.Span;
+import com.vaadin.flow.component.orderedlayout.VerticalLayout;
+import com.vaadin.flow.component.upload.MultiFileReceiver;
+import com.vaadin.flow.component.upload.Receiver;
+import com.vaadin.flow.component.upload.Upload;
+import lombok.Getter;
+import lombok.extern.slf4j.Slf4j;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+
+@Slf4j
+public class UploadArea extends VerticalLayout {
+
+    @Getter
+    private final Upload uploadField;
+    private final Span errorField;
+
+    public UploadArea(File uploadFolder) {
+        uploadField = new Upload(createFileReceiver(uploadFolder));
+        uploadField.setMaxFiles(1);
+        uploadField.setMaxFileSize(2*1024*1024);
+
+        errorField = new Span();
+        errorField.setVisible(false);
+        errorField.getStyle().set("color", "red");
+
+        uploadField.addFailedListener(e -> showErrorMessage(e.getReason().getMessage()));
+        uploadField.addFileRejectedListener(e -> showErrorMessage(e.getErrorMessage()));
+
+        add(uploadField, errorField);
+    }
+
+    public void hideErrorField() {
+        errorField.setVisible(false);
+    }
+
+    private Receiver createFileReceiver(File uploadFolder) {
+        return (MultiFileReceiver) (filename, mimetype) -> {
+            File file = new File(uploadFolder, filename);
+            try {
+                return new FileOutputStream(file);
+            }
+            catch (FileNotFoundException fnfe) {
+                log.info(fnfe.getStackTrace().toString());
+                return null;
+            }
+        };
+    }
+
+    private void showErrorMessage(String message) {
+        errorField.setVisible(true);
+        errorField.setText(message);
+    }
+}

springboot/src/main/resources/application.yml

@@ -17,6 +17,10 @@ spring:
       mode: never
   mustache:
     check-template-location: false
+  servlet:
+    multipart:
+      max-file-size: 10MB
+      max-request-size: 10MB
 management:
   endpoints:
     web: