Answers

• rf1234 Posts: 2,996Questions: 87Answers: 421

  May 2020 edited May 2020 Answer ✓

  One reason could be that you implemented the select field as a single select field and not as multi-select. Which means you are not passing an array which causes the error. Using select with an Mjoin requires the select field to be multi-select, if I recall it correctly. I found this rather complex transformation in my code to make selectize work with an mjoin and single select:

  I would recommend you change the field to be multi-select. If that works: great! If it should only be permitted to select just one value you'll need to find a way to implement it somehow ...

  editor = new $.fn.dataTable.Editor( {
     ajax: {
          url: 'actions.php?action=tblContractEntryGov',
          data: function ( d ) {
      //make selectize work with an mjoin and single select!
              if (d.action === 'create' || d.action === 'edit') {                
                  var keys = Object.keys(d.data); //array of object keys
                  var rowId = keys[0]; //row_xxx (edit) or 0 (create)
                  if ( typeof d.data[rowId].base !== 'undefined' ) {                    
                      var baseId = d.data[rowId].base;            
                      if ( typeof baseId === 'string' || baseId instanceof String) {
                          delete d.data[rowId].base;
                          if (baseId > '0') {
                              var base = []; var element = {};
                              element.id = baseId; //set property id of element object
                              base.push(element); //put element object into base array
                              d.data[rowId].base = base; //set new property of object and put the array into it
                              d.data[rowId]["base-many-count"] = 1; //set the many count as well                           
                          } else {                            
                              d.data[rowId]["base-many-count"] = 0; //set the many count as well            
                          }
                      }
                  }
              }
          }
      },
  table: "#table",
  fields: [ .... {
          label: lang === 'de' ? 
                  'Optional, Auswahl Basisgeschäft:' : 
                  'Optional, Selection of base contract:',
          name: "base[].id", //render gov_name, govdept_name
          type: "selectize", 
          opts: {
              create: false,
              maxItems: 1,
              openOnFocus: true,
              allowEmptyOption: true,
              placeholder: lang === 'de' ? 
                  'Bitte ein Basisgeschäft wählen (optional)' : 'Please select one base contract (optional)'
              }
      }, .....
  

  This field here works fine with the Mjoin without any transformation because it is a multi-select field in the same Editor instance. Same applies to using "select" or "select2".

  }, {
          label: lang === 'de' ? 
                  'Wählen Sie einen oder mehrere Verträge über Basisgeschäfte:' : 
                  'Select one or more underlying contracts:',
          name:  "underlying[].id", //render serial, instrument, type, number
          type: "selectize", 
          opts: {
              create: false,
              maxItems: null,
              openOnFocus: true,
              allowEmptyOption: true,
              placeholder: lang === 'de' ? 
                  'Bitte Grundgeschäft auswählen' : 'Please select underlying'
              }
      }, {
  
• rossbob Posts: 29Questions: 4Answers: 0

  May 2020

  Ah ok, I get it now, MJOIN is the wrong use case for what I'm trying to do. Thanks for helping me understand that.
• rf1234 Posts: 2,996Questions: 87Answers: 421

  May 2020

  The problem really is that a single select sends a different data structure to the server than a multi select that only selects one item. Even though - in both cases - only one item is being sent to the server.

  But: if you need to use a link table you need the Mjoin which expects the data structure of a multi select. (In most cases of course you won't need an Mjoin when using a single select field: It is usually just an options instance for a foreign key in the parent table. But that changes if you have self-referencing relationships which mostly require the usage of a link table even though they do not resolve an N:M relationship.)

  There are 2 work arounds:
  1. Manipulate the data structure to make the single select send the same data to the server than a multi select with one or no option selected
  2. Use a multi select field client side; if the user selects more than one value: send an error message to the front end: "Please select only one value!"

  I decided for the first work around because I found the second one not user friendly enough even though it is much simpler to implement.