4 files changed, 77 insertions, 0 deletions
diff --git a/src/main/java/dev/dnpm/oshelper/migration/DatabaseMigrationService.java b/src/main/java/dev/dnpm/oshelper/migration/DatabaseMigrationService.java
index e052286..985ccf4 100644
--- a/src/main/java/dev/dnpm/oshelper/migration/DatabaseMigrationService.java
+++ b/src/main/java/dev/dnpm/oshelper/migration/DatabaseMigrationService.java
@@ -19,7 +19,10 @@
 
 package dev.dnpm.oshelper.migration;
 
+import java.io.IOException;
 import java.util.List;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 import java.util.stream.Collectors;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
@@ -53,6 +56,11 @@ public class DatabaseMigrationService {
     log.info("Starting database migration");
     try {
       for (var migration : this.getNewMigrationIds()) {
+        if (!requiredFormRevisionAvailable(migration)) {
+          log.info("Skipping database migration due to pre-condition: '{}'", migration);
+          continue;
+        }
+
         log.info("Apply database migration: '{}'", migration);
         try {
           jdbcTemplate.execute(MigrationUtils.getSqlQuery(resourcePatternResolver, migration));
@@ -74,6 +82,39 @@ public class DatabaseMigrationService {
     }
   }
 
+  private boolean requiredFormRevisionAvailable(String migration) throws IOException {
+    final var sqlQuery = MigrationUtils.getSqlQuery(resourcePatternResolver, migration);
+
+    String formName = null;
+    Pattern formNamePattern = Pattern.compile("(?m)^-- form: (.+)$");
+    Matcher formNameMatcher = formNamePattern.matcher(sqlQuery);
+    if (formNameMatcher.find()) {
+      formName = formNameMatcher.group(1);
+    }
+
+    String minRev = "0";
+    Pattern minRevPattern = Pattern.compile("(?m)^-- min-rev: (\\d+)$");
+    Matcher minRevMatcher = minRevPattern.matcher(sqlQuery);
+    if (minRevMatcher.find()) {
+      minRev = minRevMatcher.group(1);
+    }
+
+    String maxRev = "99999999999999";
+    Pattern maxRevPattern = Pattern.compile("(?m)^-- max-rev: (\\d+)$");
+    Matcher maxRevMatcher = maxRevPattern.matcher(sqlQuery);
+    if (maxRevMatcher.find()) {
+      maxRev = maxRevMatcher.group(1);
+    }
+
+    if (formName == null) {
+      // No spezial form revision required
+      return true;
+    }
+
+    return MigrationUtils.requiredFormRevisionAvailable(
+        this.jdbcTemplate, formName, minRev, maxRev);
+  }
+
   List<String> getNewMigrationIds() throws Exception {
     var existingMigrations = MigrationUtils.getExecutedDatabaseMigrations(this.jdbcTemplate);
     return MigrationUtils.getDatabaseMigrationScripts(this.resourcePatternResolver).stream()
diff --git a/src/main/java/dev/dnpm/oshelper/migration/MigrationUtils.java b/src/main/java/dev/dnpm/oshelper/migration/MigrationUtils.java
index bde2612..fd17f22 100644
--- a/src/main/java/dev/dnpm/oshelper/migration/MigrationUtils.java
+++ b/src/main/java/dev/dnpm/oshelper/migration/MigrationUtils.java
@@ -24,6 +24,7 @@ import java.util.List;
 import java.util.stream.Collectors;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.support.ResourcePatternResolver;
+import org.springframework.dao.EmptyResultDataAccessException;
 import org.springframework.jdbc.core.JdbcTemplate;
 
 /**
@@ -39,6 +40,19 @@ class MigrationUtils {
         (rs, rowNum) -> rs.getString("update_script"));
   }
 
+  static boolean requiredFormRevisionAvailable(
+      JdbcTemplate jdbcTemplate, String formName, String minRev, String maxRev) {
+    try {
+      return 1
+          == jdbcTemplate.queryForObject(
+              "SELECT COUNT(*) FROM data_form WHERE name = ? AND revision >= ? AND revision <= ?",
+              new Object[] {formName, minRev, maxRev},
+              Integer.class);
+    } catch (EmptyResultDataAccessException e) {
+      return false;
+    }
+  }
+
   static List<String> getDatabaseMigrationScripts(ResourcePatternResolver resourcePatternResolver)
       throws IOException {
     var resources =
diff --git a/src/main/resources/dev/dnpm/oshelper/migration/README.md b/src/main/resources/dev/dnpm/oshelper/migration/README.md
new file mode 100644
index 0000000..14a530b
--- /dev/null
+++ b/src/main/resources/dev/dnpm/oshelper/migration/README.md
@@ -0,0 +1,18 @@
+# Format der Migrationsdateien
+
+Die Migrationsdateien sollen fortlaufend aufsteigend nummeriert sein, mit `.sql` enden.
+
+Zudem sollen sie immer Angaben zum betreffenden Formular und Revision enthalten:
+
+```sql
+-- form: DNPM Beispiel
+-- min-rev: 1
+-- max-rev: 2
+
+ALTER TABLE dk_dnpm_beispiel
+    MODIFY COLUMN langer_text text;
+```
+
+Ist keine Angabe zum Formularnamen angegeben, wird die Migration immer ausgeführt,
+anderenfalls nur für eine entsprechende Revision des angegebenen Formulars.
+Wenn nicht angegeben, ist die minimal erforderliche Revision ist standardmäßig 0, die maximale 99999999999999.
+\ No newline at end of file
diff --git a/src/main/resources/dev/dnpm/oshelper/migration/updatednpm_001.sql b/src/main/resources/dev/dnpm/oshelper/migration/updatednpm_001.sql
index 44c6edc..6c6d80b 100644
--- a/src/main/resources/dev/dnpm/oshelper/migration/updatednpm_001.sql
+++ b/src/main/resources/dev/dnpm/oshelper/migration/updatednpm_001.sql
@@ -1 +1,5 @@
+-- form: DNPM UF Einzelempfehlung
+-- min-rev: 273
+-- max-rev: 273
+
 ALTER TABLE dk_dnpm_uf_einzelempfehlung MODIFY COLUMN studie VARCHAR(255);
 \ No newline at end of file