From d7cb8e1072500994dedf59ed7ef94b2c48754f6a Mon Sep 17 00:00:00 2001
From: znetsixe <73483679+znetsixe@users.noreply.github.com>
Date: Tue, 21 Oct 2025 12:45:06 +0200
Subject: [PATCH 1/2] latest version

---
 src/measurements/examples.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/measurements/examples.js b/src/measurements/examples.js
index 9521a7a..63e6c3b 100644
--- a/src/measurements/examples.js
+++ b/src/measurements/examples.js
@@ -255,8 +255,8 @@ console.log(`  History: [${allValues.values.join(', ')}]\n`);
 console.log('--- Lagged sample comparison ---');
 
 const latest = stats.getCurrentValue();               // existing helper
-const prevSample = stats.getLaggedValue(1);           // new helper
-const prevPrevSample = stats.getLaggedValue(2);       // optional
+const prevSample = stats.getLaggedValue(2);           // new helper
+const prevPrevSample = stats.getLaggedValue(3);       // optional
 
 if (prevSample) {
   const delta = latest - prevSample.value;

From 1725c5b0e9ae4cf8101aa63fa55527e2d8539682 Mon Sep 17 00:00:00 2001
From: znetsixe <73483679+znetsixe@users.noreply.github.com>
Date: Thu, 23 Oct 2025 09:51:27 +0200
Subject: [PATCH 2/2] bug fixes for measurement container lagged retrieval->
 unit conversion and sample output

---
 src/measurements/MeasurementContainer.js | 58 ++++++++++++++++++++++--
 src/measurements/examples.js             | 19 ++++++++
 2 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/src/measurements/MeasurementContainer.js b/src/measurements/MeasurementContainer.js
index cc09839..1a3cab0 100644
--- a/src/measurements/MeasurementContainer.js
+++ b/src/measurements/MeasurementContainer.js
@@ -169,6 +169,50 @@ class MeasurementContainer {
       return this;
   }
 
+    /**
+   * Check whether a measurement series exists.
+   *
+   * You can rely on the current chain (type/variant/position already set via
+   * type().variant().position()), or pass them explicitly via the options.
+   *
+   * @param {object} options
+   * @param {string} [options.type]      Override the current type
+   * @param {string} [options.variant]   Override the current variant
+   * @param {string} [options.position]  Override the current position
+   * @param {boolean} [options.requireValues=false]
+   *        When true, the series must contain at least one stored value.
+   *
+   * @returns {boolean}
+   */
+  exists({ type, variant, position, requireValues = false } = {}) {
+    const typeKey = type ?? this._currentType;
+    if (!typeKey) return false;
+
+    const variantKey = variant ?? this._currentVariant;
+    if (!variantKey) return false;
+
+    const positionKey = position ?? this._currentPosition;
+
+    const typeBucket = this.measurements[typeKey];
+    if (!typeBucket) return false;
+
+    const variantBucket = typeBucket[variantKey];
+    if (!variantBucket) return false;
+
+    if (!positionKey) {
+      // No specific position requested – just check the variant bucket.
+      return requireValues
+        ? Object.values(variantBucket).some(m => m?.values?.length > 0)
+        : Object.keys(variantBucket).length > 0;
+    }
+
+    const measurement = variantBucket[positionKey];
+    if (!measurement) return false;
+
+    return requireValues ? measurement.values?.length > 0 : true;
+  }
+
+
 
   unit(unitName) {
     if (!this._ensureChainIsValid()) return this;
@@ -252,8 +296,9 @@ class MeasurementContainer {
     const measurement = this.get();
     if (!measurement) return null;
     
-    const value = measurement.getLaggedSample(lag);
-    if (value === null) return null;
+    let sample = measurement.getLaggedSample(lag);
+    if (sample === null) return null;
+    const value = sample.value;
 
     // Return as-is if no unit conversion requested
     if (!requestedUnit) {
@@ -263,12 +308,17 @@ class MeasurementContainer {
     // Convert if needed
     if (measurement.unit && requestedUnit !== measurement.unit) {
       try {
-        return convertModule(value).from(measurement.unit).to(requestedUnit);
+        const convertedValue = convertModule(value).from(measurement.unit).to(requestedUnit);
+        //replace old value in sample and return obj
+        sample.value = convertedValue ;
+        sample.unit = requestedUnit;
+        return sample;
+
       } catch (error) {
         if (this.logger) {
           this.logger.error(`Unit conversion failed: ${error.message}`);
         }
-        return value; // Return original value if conversion fails
+        return sample; // Return original value if conversion fails
       }
     }
 
diff --git a/src/measurements/examples.js b/src/measurements/examples.js
index 63e6c3b..254e61e 100644
--- a/src/measurements/examples.js
+++ b/src/measurements/examples.js
@@ -175,6 +175,25 @@ const downstreamData = basicContainer
   .position('downstream')
   .get();
 
+  //check wether a serie exists
+const hasSeries = measurements
+  .type("flow")
+  .variant("measured")
+  .exists();                // true if any position exists
+
+const hasUpstreamValues = measurements
+  .type("flow")
+  .variant("measured")
+  .exists({ position: "upstream", requireValues: true });
+
+// Passing everything explicitly
+const hasPercent = measurements.exists({
+  type: "volume",
+  variant: "percent",
+  position: "atEquipment",
+});
+
+
 console.log(`Downstream: ${downstreamVal} ${downstreamData.unit} at ${downstreamData.distance}m\n`);
 
 // ====================================